micostock basic rule book

2012 Car Specifications
Wall Sunday Series Microstocks

Microstocks are open-wheel modified stockcar inspired go-karts, and race on paved and dirt oval tracks. They are larger than open style karts and feature bodies, full roll cages and seat belts. Racing kart style one cylinder 4 cycle engines are used for power. There are several classes for loads of affordable fun!
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MRL Contact Information
For more information, explanations, to schedule a race or speak to someone please contact one of the below members of the MRL.
Nick Cottone 732-929-2256 e-mail- patio737@aol.com Dennis Hiddemen 215-262-3227 e-mail-dhiddemen@verizon.net Jeff Weinacker 201-230-5719 e-mail-jwwmanus@aol.com Disclaimer
....The MRL, This set of rules, its publisher and all contributors will not be held responsible for any injuries. It is the car owner and drivers responsibility to ensure their own safety. This set of rules is as a general set of guidelines and each division racing will have slightly different rules and each track will have different Tech and safety rules. Check with your local track and Tech officials for more detailed information.
By building and or Racing any form of car or Microstock the builder and driver will assume all responsibility.
* Mission Statement *
Microstock Racing presents an opportunity for men and women to share their passion for auto racing in
an atmosphere of friendship and camaraderie. Rules and guidelines shall be established to provide fair competition at a reasonable cost. However, sportsmanship, friendship and fun shall be the primary goal of each race day.
BASIC RULES
1. State regulations shall be met in any State where a race is conducted. 2. The primary engine package shall be a stock World Formula sealed by J.C. Specialties. 2a. Other motor packages are being considered but currently not scored. 3. Minimum weight of car and driver shall be 450 pounds. 4. Maximum tread width 48" measured outside/outside wheels and tires. 5. Maximum length of 96" bumper to bumper 6. Maximum height of 42 inches. (More detailed rules follow) Page 3
LOCAL GROUP PROCEDURES
There are several major groups of Microstock Racers, not counting the Modified Outlaw Microstocks
(MOM) : Mahoning Valley, Wall Stadium, Borgers and the World Modified Tour Any group wishing to race at a track regularly attended by another group shall contact the regulars as a courtesy before contacting the local promoter.
The rules and procedures of the local group shall prevail. However, the visitors may score themselves separately and pay out as they choose. Under no circumstances shall a visiting group exclude the local group from participation.
RACING
1. No Microstock shall be denied the opportunity to race. If the car does not meet the engine rules, they shall be allowed to start last and not be officially scored. An identifying ribbon may be required. Every opportunity to increase the field of cars shall be taken. 2. Modified (MOM) cars [2 or less] shall be permitted to race from the front of the field for safety. 3. Winners of previous races shall start at the rear of their next race. 4. Any non-points race held at a local track shall be governed by the local rules. Page 4
Table of Contents
1 Points System 2 Motor Packages/Classes 3 Flagging 4 Racing Procedures
Heats Feature Line Up Post Race Inspection Penalties Three Driver Panel
5 Driver Safety 6 Car Specifications 7 Car Safety Items 8 Motor Seals Appendix
FL Flat Head (Mahoning rules) CS Controlled Stock Motors (last known WKA specifications) WF World Formula Motors
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1. Points System Points system is to be used as laid out below
1.1.1 Heat races are not scored 1.1.2 Feature finish order as supplied by the track will be used for scoring purposes. 1.1.2a Non Conforming cars will be dropped from the finish order. 1.1.3 Scoring will be from the rear of the field forward and will be paid in 10 point increments. 1.1.4 Winner receives a 10 point bonus. 1.1.5 Scoring details. Last = 10 points Next to last = 20 points and so on in ten point increments. Winner to get an additional 10 bonus points. 1.2 Championship Points Championship points will be as follows. 1.2.1 All Eligible competitors must run 50% of sanctioned points races. It is the competitors responsibility to get the finish order. In the event the track can not supply a full finish order the sanctioned even will become a non points race. 1.2.2 There will be 2 drops from the points allowed. Any disqualification or revoked points day due to an infraction can not be used as a points drop day. 1.2.3 Rankings will be according to total points in descending order. 1.2.4 All competitors must register with the MRL and must include the motor seal numbers. 1.2.5 The Club Fee (if any) will go towards a year end cash payout or trophy to the champion and an equal amount to one eligible competitor chosen at random in the event of a payout. (Less operating expenses) 1.2.5a Other Awards Additional awards may be added such as “Hard Charger” or “rookie of the year” and appropriate payout to be determined.
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2.1 Microstock Divisions 2.1.1 Microstock divisions are set apart by motor only in the effort to keep microstocks as similar as possible. If one motor package can be chosen by all the World Formula is suggested. This is for its power , reliability, economical option as well as the ability to change between coils* for reduced power classes. In addition a WKA animal restrictor plate my be required for some tracks. * The World Formula motor uses a PVL ignition system with a built in Rev Limiter. Other groups and divisions may utilize a different rev limiter to reduce the power for Jr classes or reducing speeds. Currently the only accepted rev limiter is the red PVL that limits at 7100 RPM. There are others available that limit at 4100, 6100 and 12,000. None of these are approved for competition at this time. 2.1.2 Non Conforming Any motor combination different from what is set forth in this book is considered to be “Non Conforming” As such these cars will not be scored and will be required to run an identifying ribbon tied to the highest most point on the car to make them easily identifiable to other competitors and track officials. All Non Conforming cars must start at the rear of the field for heats and features. 2.1.3 Development Class This class is designed to be an entry level for beginners and younger drivers using stock or limited power motors with few or limited alterations from stock. Specifications of motors is to be added. 2.1.4 WF/Flat Head/CS **see appendix** WF CS and FL for exact specifications. This class is to run only the World Formula and Flat Head motors as laid out in the motor appendix. Similar horsepower motors areallowedbynot scored.All non conformingstartallheatandfeatureraceswith aRibbon affixed to the roll bar top most location and will not be scored. ***NOTE*** it is the intent of the Wall Sunday series to go with all Briggs sealed World Formula Motors. The Flat head Controlled Stock and Flat head stock carburetor may or may not be scored, we highly recommend procuring a sealed World Formula motor for competition.Motor Rules can be found in the appendix section of this rule book. 3.1 Flagging 3.1.1 Track officials are to be respected at all times and their on track rulings areto be accepted. Racing procedure is to be in accordance to all track regulations, flags and procedures. 3.1.2 Flags All competitors must understand and comply with flags and flagging rules. 3.1.3 Red Flag When displayed all cars must immediately come to a stop and await instructions from track officials. 3.1.4 YellowFlag Caution flag isdisplayed when the track is not open for competition. Cars are to form up in starting or restarting position and proceed at a slow pace. It is recommenced that if an on track incident occurs thattakes moretime than expected the leader can stop onthestart finish line to allow track workers open working room. 3.1.5 Green Flag Signifies the start of the race, track officials will designate a starting line and when or where passing can begin. Page 7
3.1.6 White Flag The white flag is the “one to go” signal. 3.1.7 Checkered Flag Checkers signifies the end of the race. 3.1.8 Blue flag with Yellow Stripe This is the “move over” Flag to let a slower car know the leaders are approaching. 3.1.9 Black Flag This is given when a car must immediately stop competition. That car must proceed to thedesignatedarea immediately.Atsome tracksthisisthe infield,atothersthere isanexit rampthatissafe to use during competition. 3.1.10 Combinations of Flags The above flags may be combined by the flagman to give information during the race. For instance, 2 rolled up flags creating an X is generally considered the half way signal. Tworolledup flags held side by side is considered the “two to go”signal.Arolled up white andgreenmay be the green next time by signal. 4.1 Racing Procedure 4.1.1 Exiting Competition During a race, any car brought back to the pits will not be permitted to reenter that race unless the track officials allow it. 4.1.2Exiting theVehicle Anydriver exiting hisvehicleduringarace,unlessinstructedby track officials, shall not be allowed to complete that race. (Practice, Heat or Feature) 4.1.3 Red Flag Condition Failing to come to an immediate safe stop under the red, for any reason, disqualifies a car from completing that race. (Practice , Heat or Feature) 4.1.4 Displayed Black Flag If track officials see any problem with any car, that car will be black-flagged, and the flagged car must proceed to a location designated by track officials. 4.2 Race Day Time Line 4.2.2 Pre Race Sign In All competitors are to sign in as required by the track. In the event there is no technical inspector all competitors must also sign in with the MRL representative. 4.2.2PreRaceTechnicalInspection Pre race technical inspectionwill includesealnumberverification, coil type verification and safetypre race brake check. Additional items may be chosen by track officials and or technical inspector if provided. 4.2.2a Pre Race Technical Inspection when no inspector is provided When there is no track provided technical inspector, all competitors will become Technical inspectors. The sign in sheet will be used for the list of competitors and names placed in a hat, each competitor will be draw from a hat for another competitors car to tech without prejudice. A check sheet will be provided.
4.2.3 Heat Lineup The heat lineup will be by the existing track system, in the event no track system exists the starting positions will be drawn by pulling numbers. All Non Conforming cars will fall in behind scored cars. Page 8
4.2.4 Multiple Heat Races When the field of competitors exceeds 12 cars the heat races are to be split in two, odd starting positions to heat one and even starting positions to heat two. 4.2.5 Feature Lineup Feature lineup will be by heat race finish order, in the event of two heat races the finish lineup from heat one will line up on the inside lane while the second heat will line up on the outside. All non conforming cars to fall in behind in their respective finish orders. 4.2.6 Race Winner’s Next Event The winner of the last sanctioned race must start their next race from the rear of the field behind all scored cars, but in front of non scored cars on the feature only. In the event of multiple winners the most recent is to start behind the next most recent.
4.3.0 Post Race If track scales are available all competitors are to cross the scales immediately following the race, If track scales are not available the top four are to proceed to post race technical inspection area. 4.3.0a Post Race Technical Inspection Post race inspection is to consist of seals, coils, width and weight as laid out in 4.3, the track Technical inspector may add to the items being inspected at any time.
4.3.3b Post Race Technical Inspection when no inspector is provided For Post race inspection the names will be returned to the hat and 3 more will be drawn. These competitors will be responsible for the post race inspection as laid out in section 4.3. In the event one of the inspectors is in the top three, a replacement name will be drawn from the hat. In the event any infraction is found it is to be verified by the other two inspectors.
4.3.1 Top three after the feature are to be weighed 4.3.2 A random performance tech item may be drawn and inspected 4.3.3 Seals will be inspected and seal numbers to be recorded. 4.3.4 Coil type to be inspected after each event 4.3.5 Maximum tread width 48" measured outside/outside wheels and tires. 4.3.6 Technical Inspectors in the event the track does not provide any All competitors are pre race technical inspectors and are allowed to inspect anyone’s car at any time. This is made possible by the motor seals that pre tech the internal portion of the motor. 4.3.7 Any illegal components may be confiscated and not returned to the competitor. 4.4 Technical Offence Levels (all of section 4.4 may be superceded by track rules) The technical infraction found will be judged by the 3 driver panel and assessed in to one of the below categories and the appropriate action taken unless superceded by the track officials.
4.4.1 Offence Level One A level 1 offence will be for anything that does not constitute an advantage and is not safety related. There is no penalty, but the problem must be corrected before the next race. Page 9
4.4.2 Offence Level Two A level 2 offence will be if a definite speed or performance issue is identified. This offence will then go to a 3 driver panel (See 4.6.1) who will rule if it was intentional or non intentional. 4.4.2a For a non intentional ruling the infraction must be repaired before the next race. 4.4.2b For an intentional ruling, the points and or payout are forfeited and a DQ is issued the following day.
4.4.3 Offence Level Three A level 3 offence is one that is a competitive advantage, was brought to the attention of the car owner and made clear by the panel of 3 drivers and the competitor refused to make the appropriate changes and returned to the track without making said changes.
4.4.3a A level 3 may result in banishment for 1 week to one full year depending on the severity as ruled on by the 3 driver panel.
4.4.3b. Engine Offence If a sealed World Formula is intentionally tampered with or altered, the participant must make competitors aware prior to entering competition for the day and must run a ribbon to signify a non scored or non conforming car. Alternately if a seal is cut to replace the PVL system the coil is subject to part number and color inspection and the cutting of the seal must be made known to all other competitors and the 3 driver panel.
4.5 Protest and Tear Down Procedures 4.5.1 Both parties involved in a protest shall put up front the amount equal to the cost of a Tech Inspection and shipping. If the motor in question is found to be legal, the owner’s funds are returned and the protestors funds are used to pay for the cost of inspection. If the owners motor is found to be illegal the owners funds are used to pay for the inspection and the protestors funds are returned. The owner of the illegal motor will also loose double the points earned for that day. 4.5.2 Both parties are allowed to be present during the tear down 4.5.3 Tear Down is to take place at JC Specialty at the earliest convenience. 4.5.1 The 3 Driver Panel A three driver panel is to be chosen to settle disputes infractions. The method of choosing this panel on any day will be to put all competitors names in a hat except for those involved, then to pull 3 names out of the hat. These three names will be the panel selected to settle any disputes. The panels rulings are final. Page 10
5.1 Driver Safety Gear Recommendations 5.1.1 All drivers must wear the required safety gear at all times during competition. Additional safety gear may be required by the track and must be complied to for competition. 5.1.2 Fire suits Drivers must wear a one-piece SFI rated fire resistant suit, SFI rated flame-retardant gloves covering their bodies, arms, legs and hands. 5.1.3 Underwear SFI rated Fire resistant long underwear tops and bottoms are recommended. 5.1.4 Helmets: .A full Face SA2005 or SA2010 helmet must be worn for competition 5.1.5 Head, Neck & Arm Restraints: Neck Collar or HANS type Head and neck restraint must be worn at all times. 5.1.6 Arm Restraints Arm restraints are mandatory to prevent driver's arms and hands from reaching outside the cage. 5.1.7 Vision Aids: Prescription lenses noted on the competitors driver's license must be worn during a racing event. 6.0 Car Specifications 6.1 Bodies Bodies must be complete at the beginning of competition 6.1.1 Must be fiberglass, metal or polycarbonate, enclosing a minimum of 70% of driver’s area. 6.1.2 All cars must have an opening large enough to provide rapid exit of driver from vehicle. 6.1.3 Side windows must be open at least 6.5” x 12” to provide emergency access to cockpit. Body panels must not impair driver’s side vision. 6.1.4 Cars must have a closed roof that can be opened from either the inside or outside. Roof must be secured with a mechanism that prevent accidental opening. 6.1.5 Cars must have a recognizable Dirt Modified or Asphalt Modified body style. 6.1.6 Car numbers must be minimum of 10” tall and placed on roof and both sides as well as a minimum 4" tall number on the rear. All numbers must be legible for scoring purposes and roof numbers must be readable from the right side of car. 6.1.7 If a track scorer requests a change in your number scheme, you must comply. 6.1.8 No wings allowed. 6.1.9 Any bars that can strike the driver’s head or torso must be padded. Page 11
6.1.10 Large openings between the floor pan and body must be covered by steel ½" X ½" screening to prevent debris from entering driver compartment. This does not include side window openings that are to remain free of obstruction. 6.2 Brake System 6.2.1 Brake systems must be operational prior to competition 6.2.2 Must be foot-operated by pedal. 6.2.3 Mechanical or hydraulic disc brake only. 6.2.4 Both rear wheels must brake. If brakes are also mounted on front wheels, both front and rear must work together. 6.2.5 If the Caliper has shim packs the brake caliper halves must be wired together to keep the shim packs in place. 6.2.5.1 Brake caliper must be bolted with bolts being either cotter keyed or double nutted 6.2.6 Brake rotor bolts must be double nutted or cotter keyed 6.3 Bumpers 6.3.1 All welds must be complete: top, sides and bottom. 6.3.2 All cars shall be equipped with bumpers on the front and rear of the vehicle. 6.3.2.1 All bumpers must be constructed as not to hook or catch on to another competitors bumper 6.3.3 Bumpers must be made of 16 gauge (.065”) minimum ¾” steel, tubular or square stock or a minimum of 1” diameter .100” wall thickness aluminum. Channel bumpers are not permitted. 6.3.4 Must be 3”-5” from the ground to the bottom of the lowest rail and at least 6” from the bottom of the lowest rail to the top of the top rail. Must have a minimum of 3 connecting bars spaced evenly. 6.3.5 The rear bumper must cover the full width of the vehicle to at least the center of the rear tires, but not to extend beyond the outer edge of the tires. 6.3.6 The front bumper shall be a minimum of 15” and a maximum of 24” wide, centered between the main frame rails where they attach to the front of the frame. 6.3.7 All bumper ends must be radiuses or boxed to prevent hooking other cars. Page 12
6.4 Exhaust System 6.4.1 Exhaust system must be complete 6.4.2 The exhaust system on all cars must be a minimum of 3” from any tire and is not included in measurements of the overall length of car. 6.4.3 The exhaust must exit to the outside of car body (must not exhaust in to an enclosed portion or in a method to trap the gasses near the driver). 6.4.4 Clamped on muffler must have a tether and must be in place. Welding of the muffler to the tail pipe is permitted. 6.5 Fire Wall and Flooring 6.5.1 Full Fire wall and flooring must be complete at all times 6.5.2 All cars must have a minimum of .030” thickness firewall completely sealing driver from fuel supply, fuel lines and engine compartment. 6.5.3 All cars must have a minimum of .030”thickness metal floor plan with no openings between the driver and ground. The floor pan must cover the complete underside of the driver’s compartment from nose to behind seat or beginning of firewall, in order to shield driver’s body from the ground. 6.5.4 Any large openings between floor pan and body must have steel ½” x ½” screening or protective covering to prevent track debris from entering driver compartment. 6.6 Fuel Lines and Fuel Tanks: 6.6.1 No fuel lines are to be run through the drivers compartment 6.6.2 No fuel tanks are to be mounted in the driver"s compartment. 6.6.3 Fuel lines must be three (3) inches from any exhaust system. 6.6.4 Fuel tanks must be an approved type fuel cell. They may not extend outside of the car, and they must be protected from impact with a steel bar. 6.6.5 External fuel tanks must have a shut-off valve and fuel lines must be clamped or safety wired. 6.6.6 A spill proof cap must be used to prevent leakage of fuel in the event of a rollover. Page 13
6.7 Fuel Cell 6.7.1 A Fuel Cell is recommended (not required) such as the 2 quart model by JAZ designed for Jr Dragster applications. This model includes internal foam, vent and 1/4" outlet with shutoff valve. Jaz part number 230-050-01. 6.7.2 Mounting must be in accordance to all safety regulations. 6.7.3 A fire wall may be required between the Fuel Cell and engine compartment. 6.7.4 The Fuel cell must not be mounted in the drivers compartment and a fire wall must separate the drivers compartment from the fuel cell. 6.8 Frames 6.8.1 All frame welds must be complete: top, sides and bottom. 6.8.2 All frames (chassis) must be made of a minimum of 16-gauge (.065”) 1” diameter tubular or (.065) 1” square stock, seamless wall or welded wall, steel or better quality. 6.8.3 Cars must have at least two bars (0.65” minimum ¾” diameter), positioned above and outside the driver’ feet and legs to prevent a car from landing on them. 6.8.4 Stub axle and axles must be rigidly mounted (bolted or welded) to the chassis such that there is only UNSPRUNG weight. No SPRUNG weight allowed. 6.8.5 Hydraulic or pneumatic shock absorbers affecting motion of axles or stub axles are not permitted. 6.8.6 A visual check should reveal no springs controlling rotative axle or stub axle motion. 6.8.7 All cars must have a footrest or heel stop to prevent feet from sliding out the nose of the vehicle. 6.8.8 Side roll cage protection must be made of a minimum of 16 gauge (.065”) ½” diameter tubular, or (.065”) ½” square stock, seamless wall or welded seamed wall, steel or better quality. 6.8.8.1 Sidebars must be placed to prevent intrusion by another vehicle into the cockpit area. 6.8.8.2 All cars must have minimum of sidebars, placed horizontally, vertically or diagonally. Nerf bars cannot substitute for bar protection. Page 14
6.9 Head Rests 6.9.1 All cars must have either a high back aluminum racing seat with integral head rest or a separate head rest cushion. 6.9.2 Head Rest With Aluminum Seat The integral head rest on the aluminum seat must be at the approximate height of the center of the driver’s helmet. It must be within the main roll-cage, as viewed from the rear and sides. When in driving position, the back of the driver’s helmet must rest against the headrest. 6.9.3 Head Rest Cushion If the seat does not have an integral headrest a cushioned headrest must be mounted directly behind the driver’s head. The cushion shall be mounted so that it is at the approximate height of the center of the driver’s helmet It must be a minimum of 4” and 2” thick. It must be within the roll-cage, as viewed from the rear and sides. When in driving position, the back of the driver’s helmet must rest against the headrest. 6.10 Dimensions 6.10.1 Height A car may not be higher than 42” or lower than 30”, measured from the ground up (with tires on), to the highest point on the body. Additional roll cages exterior to the body are not included. 6.10.2 Width May not be narrower than 37" or wider than 48", measured from left tire or rim to right tire or rim what ever is widest. Measured on both front and rear of the car. 6.10.3 Length A car may not be shorter than 78” or longer than 96”, measured from bumper to bumper. 6.10.3a Length does not include air cleaner or exhaust
6.11 Weight/weights (All cars except MOM) 6.11.1 Minimum weight of car after race is 225 lbs. without driver 6.11.2 Controlled stock will run a minimum of 450lbs 6.11.2.1 All other Flat head classes are to run 450 lb minimum weight 6.11.3 World Formula Class will run a minimum of 450 lbs. 6.11.4 Removable ballast must be secured to the welded chassis or other part of the car with bolts and cotter key/safety wire. Ballast must be painted white and numbered to match the car. Page 15
6.12 Ignition Safety Kill Switch 6.12.1 Cars must be equipped with a safety kill switch that will shut off the ignition from the motor. 6.12.2 Switch must be accessible within driver’s compartment 6.12.3 Must be conspicuously labeled ON and OFF. 6.13 Mirrors and Radios 6.13.1 No mirrors or radios allowed in car. 6.14 Nerf Bars 6.14.1 All welds must be complete: top, sides and bottom. 6.14.2 Must be made of Steel or aluminum. 6.14.3 Steel bars Must be made of a minimum of ¾”, .065” tubular or square stock steel and have a minimum of ¾” over rider bar welded on top or a minimum of ¾”, .065” tubular or square stock steel or under-rider bar welded on bottom. 6.14.4 Aluminum bars must be a minimum of 1" diameter .100 tubular and have a minimum of 1” over rider bar welded on top or a minimum of 1”, .100” tubular or square stock steel or under-rider bar welded on bottom. 6.14.5 Must extend within 2” of, but not more than 1" beyond, the outside edge of the rear tires. 6.14.6 Must be within 4” of the rear tires. 6.14.7 Must be a minimum of ½ the length of the wheelbase. 6.14.8 Must be welded or bolted securely to the frame. 6.15 Oil Catch Can 6.15.1 Catch can must be in place prior to competition. 6.15.2 An oil catch can, must be mounted inside the body constructed such that oil blow-by cannot leak onto the track. 6.15.3 All oil blow-by from the engine breather system must be routed to an Oil Catch Can. 6.15.4 The oil catch can, must be vented only to outside air. No connection to carburetor or exhaust system permitted. Page 16
6.15.5 The total area of all vent lines from the can must be greater than the total area of all lines connecting the can to the engine breather system. 6.15.6 Must not leak oil on track. 6.16 Fuel Over Flow 6.16.1 All World Formula motors must have the fuel overflow run to a catch can. This can is to be separate from the oil overflow. 6.17 Roll-Over Bars 6.17.1 All welds must be complete: top, sides and bottom. 6.17.2 All cars must have a roll-cage with sidebar protection. The main roll-cage must be made of a minimum of 16 gauge (.065) 1” diameter tubular or (.065) 1” square stock, seamless wall or welded seamed wall, steel or better quality. 6.17.3 Roll-cage bars must have steel gussets welded in at the four top main joints. 6.17.4 All roll-cages must be welded to the main chassis of the car, with gussets at all welded structural joints as appropriate. 6.17.5 The roll-bar must clear the driver’s helmet by a minimum of 3”, measuring from a line between the bottom of the roll-bar and the top front of the roll-cage. 6.17.6 Driver’s head and body must be entirely enclosed within the roll-cage and car body. 6.18 Safety Belts 6.18.1 Cars must be equipped with double over-the-shoulder harness, 3” lap belt and sub strap, with a single quick release. 6.18.2 Belts must be fastened to the frame of the vehicle at both ends of lap belt and end(s) of shoulder harness and sub strap. 6.18.3 Shoulder belts are to fastened to the frame according to manufacturers recommendation and mounting to be within 6" of the drivers shoulders. 6.18.4 All fittings and connections on belts must be metal and bolts, if used, must be grade 5 or better. 6.18.4a If bolts are used they must be cotter keyed 6.18.5 “Cam-Lock” type seat releases will not be permitted. 6.18.6 Belts must comply with local regulations regarding age from date of manufacture. Page 17
6.19 Seats 6.19.1 Seats shall be attached to the frame of the vehicle, the roll-cage or to a metal plate attached to the frame or base or front of the seat, no more than 4” from the outside edge of the seat at the two most practical widely-spaced points and bolts shall be installed at the two practical widely-spaced points at the top of the back of the seat. The use of a fibreglass seat requires a metal strap at least 2” in width connecting every 2 bolts on the inside of the seat. 6.19.2 All bolts must be a minimum 5/16” diameter grade 5 or better. 6.19.3 Vehicles with metal seats do not need required straps, but do require larger washers at each bolt. 6.20 Steering 6.20.1 Cars must have direct mechanical steering with all axle linkage bolts and nuts cotter-keyed or safety-wired. 6.20.2 All rod ends must have aircraft quality universal-type swivel joints. 6.20.3 Universal joint steering systems must be welded, except where it bolts to a rack. Must be secured safely to rack. 6.20.4 Hollow steering shafts must be made of a minimum of .065” steel or better quality tubing. 6.20.5 Tie rods may be hollow aluminum or steel or solid steel. Solid tie rods must have a minimum diameter of 5/16” and may have threaded ends. 6.20.6 Tie rods made entirely from threaded rods are not allowed. 6.20.7 All bolts used on steering components must be cotter keyed 6.20.8 Steering wheel must have a quick disconnect and bolts are to be safety wired 6.20.9 An optional 4" diameter 2" thick foam pad is to be mounted on the center of the steering wheel. 6.21 Tires and Wheels Tires and wheels must be manufactured specifically for racing competition. 6.21.1 Maximum wheel diameter not to exceed 6”. 6.21.2 Maximum tire diameter not to exceed 15”. 6.21.3 Any approved for racing competition tire brand may be run 6.21.4 All wheels must be made of quality construction and material approved for racing competition. 6.21.5 All wheel axles must be cotter-keyed or C-clipped. 6.21.6 Live rear only. No slipper or ratchet hubs-both rear wheels must be fixed. Must use all keys. Page 18
6.22 Wheelbase Wheelbase may not be shorter than 52” or longer than 67”, measured between the centers of the front and rear axles. 6.23 Windshields 6.23.1 Required, made of metal screening with a maximum spacing of steel ½” x ½” or clear Polycarbonate, covering entire windshield area. 6.23.2 No glass anywhere on car. 6.24 Clutches 6.24.1 Centrifugal dry clutches only (#35 chain only). 6.24.2 Quick-change sprockets allowed. 6.25 Chain Guard 6.25.1 A Chain guard must be run at all times 7.1 Car Safety Items 7.1.1 All Steering linkages are to be cotter keyed, safety wired or “safety clipped” 7.1.2 Steering wheel bolts are to be wired 7.1.3 Brake rotor bolts are to be wired or double nutted 7.1.4 Caliper bolts are to be wired or double nutted 7.1.5 Caliper halves are to be wired together in such a way that the shims do not fall out (if applicable) 7.1.6 King pins are to be cotter keyed or safety clipped 7.1.7 Rear axle “C” clips are to be safety wired 7.1.8 Steering wheel is to have a 2" thick 4" diameter pad unless the tachometer is mounted in the center 7.1.9 All cars are to have a head rest approximately in the center of the drivers helmet, a high backed Aluminum seat is to be considered a head rest for cars with such a seat. 8.1 Motor Seals 8.1.1 Seals for the WF class will be done by J.C. Specialty only 8.1.2 No competitor is allowed to have the seal tool or un clipped seals in their possession at any time. Page 19
8.1.3 Seals done by competitors are illegal and that competitors seals are to be considered void as well as all points removed for any completed races for the season the violation occurs in. 8.1.4 Unsealed motors are subject to full tear down at the track and cars containing an unsealed motor will not receive any points or payout. 8.1.5 Everything under a sealed portion of a motor is to be considered inspected and passed. 8.1.6 Motor seal numbers must be registered with the MRL 8.1.7 in the event the shroud seal is missing there must be an inspection port drilled on the shroud. The coil and flywheel key must be inspected before any competition to be considered for points. 8.1.8 Only the red PVL 7100 rpm coil is accepted for use in the World Formula engine at this time. Page 20
Appendix FL
FL.1 BRIGGS & STRATTON FLAT HEAD (Under Review) Mahoning style FL.1.1 Carburetor shall be stock bore (.690) and inspected with a go / no go gauge FL.1.2 Block must remain stock on the outside. FL.1.3 No welding above the cooling fins. Weld below the cylinder are permitted for block repairs FL.1.4 Stock steel 5 HP flywheel only FL.1.5 Any ridged exhaust pipe and muffler may be used. FL.1.6 Stock tank must be used. FL.1.7 Stock stroke crank must be used FL.1.8 No more than .120 over stock bore
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Appendix WF
WF.1 World Formula Motor Package
WF.1.1 Alterations: No alterations of any sort permitted. Engine must remain as purchased with the exception of the following. A) Animal quick change throttle plate may be added B) Manual pull starter may be removed and screen installed C) Starter nut for external starter may be installed D) Carburetor Jets may be changed E) aftermarket air filter with the correct inlet flange may be used (no adaptor) F) aftermarket fuel pump may be used G) updated stock parts may be used (replacing a Gen 1 block with Gen 4 or higher)
WF.1.2 Starter: Stock starter must be in place at all times. Starter must be operational at the start of competition to receive any points or payout. Starter must remain on the motor.
WF.1.3 Battery: Battery must be in place at all times for competition. Batteries must be secured and shielded to prevent leakage in the event of a turnover. If the battery is located within the drivers compartment The battery shall be enclosed by battery box, covered and secured to the vehicle as to not allow movement of the battery. If the battery is located outside the drivers compartment all bolts must be cotter keyed or wired.
WF.1.4a Fuel The World Formula motor is to be run on Pump Gas 98 Octane as recommended by Briggs and Stratton. However with the recent addition of Ethanol to many commercially available fuels, a Racing “pump” Gas is recommended with no aftermarket additives.
WF.1.4b Fuel Lines: No fuel line is to be run through the drivers compartment.
WF.1.5 Intake Filter: Air filter must fit carburetor intake without an adaptor. Must be in place at all times. Any air filter meeting these requirements is permitted.
WF.1.5b Intake Clean Air Box: Any Clean air intake must be such that funneling of air is not intended or a result. Air filter must remain in the stock location. A box can be constructed around the air cleaner however it must be fully open with the top or side edge and level as not to “scoop” any additional air.
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WF.1.6 Walbro Carburetor: Carburetor must remain in stock un altered condition. Float height, jet size, and needle height are non Tech Items
WF.1.7 Intake Mounting: Rear Engine Microstocks may not invert the intake manifold or run the Animal intake to maintain all motor components within the rear bumper. No alternate intake manifolds will be accepted. No porting, matching or polishing of the manifold is permitted.
WF.1.8.1 PVL For the WF/CS class only the red PVL ignition is to be used limiting at 7100 RPM the black limiting at 4100 RPM, green limiting at 6100 RPM and blue limiting at 12,000 RPM are not to be used.
WF.1.9 Exhaust: Any non moving exhaust pipe is permitted. Exhaust must exit the body work, be at least 3" from any fuel lines and be pointed away from the tires.
WF.1.10 Muffler: Modified Muffler permitted. (RLV part number 4106) No alterations to muffler permitted. Welding of the muffler to the exhaust pipe is permitted.
WF.1.12 Special Consideration to the WFMT Seal: The WFMT motor seal is to be taken as part of the motor. If an issue involving tear down arises, the seal is to be considered part of the motor and to be replaced at no cost to the protestor or protestee whom is found to be correct in the event the seal must be broken for tech inspection or “protest”. (See Protest Procedures)
WF.1.13 Welding: Welding on the block is permitted to repair broken rod damage on sump housing only, no welding on cylinder from cooling fins to top of the block. Weld Repairs of the exhaust stud bolt holes is permitted with no protrusions or modifications allowed to the exhaust port.
WF.1.14 Rebuilding the World Formula:
Anyone can rebuild the engine. However, once rebuilt it is to be re sealed by JC Specialty.
WF.1.5 Internal Specifications:
Internal World Formula motor specs must remain as stock. .035 over maximum cylinder bore (on Rebuilds) Only stock Cam or cam profile is permitted Stock/oversize piston allowed are Briggs part numbers 557121, 557122, 557123,557124 No balancing, No stroker cranks No aftermarket connecting rod No porting No matching of mating surfaces. Stock head gasket must be used Stock valves must be used Stock valve springs must be used
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Stock rocker arms must be used Unaltered stock head must be used. No aftermarket rings (must use stock or oversized stock) No alterations to the stock PVL ignition system No tampering with the Rev Limiter Rev Limiter must be in working order No Aftermarket parts permitted internal to the engine.
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Appendix CS
Controlled Stock Specifications
NOTE: All parts must be Briggs & Stratton factory production parts unless otherwise specified. No machining or alterations are permitted unless specifically noted. Any parts that are to remain stock are subject to be compared to a known stock Briggs and Stratton part. No reading between the lines. If it’s not in the rules, it must remain stock. No titanium parts allowed, UNLESS OTHERWISE STATED ENGINE WILL BE TECHED AS RACED.
CS.1 SHROUDS & COVERS: Engine shroud and covers must be intact and not modified, except Scatter Shroud made by W.E. Chapps may be used. This includes flywheel shroud unless there are no holes in block for it to be used. Taping of shroud housing allowed. Tape on block disallowed. Fixed screen must be affixed to shroud cool air intake area. Any bolt utilized to secure sheet metal, shrouding, etc. with the exception of sheet metal secured by the head bolts, may be replaced with large diameter bolt(s).
CS.2 HEADER/SILENCER: Exhaust pipe/header must extend beyond gas tank be a minimum of 3" from rear tire and have no exposed sharp edges. Header/exhaust pipe MAY NOT PROTRUDE inside of exhaust port so as to alter port configuration for performance gain. Studs allowed for header pipe attachment to block. Exhaust may protrude past the rear bumper by approximately 5"
NOTE: WKA In events where silencing device is MANDATORY (Divisional, National, etc., points event and where required for non-points, local events), use of RLV 8-91 SILENCER IS MANDATARY. Silencer must be utilized as produced, with no modifications or alterations permitted.
CS.2.1 only RLV part number 4106 muffler is to be used.
CS.2.2 Gasket and/or Silicone allowed to seal the header.
CS.2.3 Header must be of fixed design, NO SLIPPY PIPES allowed. No extra tubes or extra holes allowed except hole for heat sensor probe if sensor is used.
CS.2.4 All header pipes must be of continuous length from flange to end of pipe with stages or butt welds permitted (no chamber, infusers or covers of any type allowed on muffler etc.) Silencer must be visible when viewed from any angle. Header tube and silencer only legal parts.
CS.2.5 Extra HEAT SHIELD above chain guard IS ALLOWED.
CS.2.6 A header support brace and safety wiring of header bolts is MANDATORY to assure header bolts remain tight. It is recommended that the safety wire wrap around pipe to insure that bolts remain with pipe in case they are stripped out of block. Silencer must be tight, secure and completely intact on the header throughout the entire event. Silencer must be clamped to header tube and no welding of silencer in any area.
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CS.2.7 The use of exhaust block saver is allowed. It must be round with a 0.75 inches min. and 1” maximum thickness and be made of ALUMINUM. Must have a straight bore with a 1.005 MUST GO ID. Bolt holes must have stock cord diameter.
CS.2.8 RLV part number 4106 muffler must remain as purchased. No alterations allows
CS.3 AIR FILTER: Any air cleaner permitted that is installed in a safe manner. Filter may not be used as an air ram and must filter from all areas as raced. Any open areas in filter must be covered with a filter sock. (No open areas allowed).
CS.4 FUEL TANK: Tank cap MUST be stock and in the stock position. Brace on tank bracket IS permitted. Stock gas cap must be utilized. No overflow tube is allowed. Acceptable cap is stock Briggs & Straton domed cap with single vent hole and stock gasket or old style cap with metal insert (See Fig. 701.4). Cap splash shields are not permitted. Bungee-type strap may be used in ALL CLASSES to wrap around engine and fuel tank to prevent loosening of parts from vibration. One of two gaskets allowable on carburetor/tank joint. Only one gasket allowed Carb to tank with Blue Print-O-Seal is used in pick up cup of fuel tank, however an open a lot must be visible at the top of the pickup cup. (Min. distance of .062”) (See Fig. 701.4)
NOTE: INSTALLATION INSTRUCTIONS FOR TANK REPAIR KIT: (See Fig. 701.4) CAUTION: Fuel cup insert may have sharp edges, handle with care.
1. Remove fuel tank from engine and remove old gasket. 2. Roll fuel cup insert into a coil 1” in diameter or less with tab on outside of coil and insert into the fuel cup in tank, Fig. #1. 3. Tab should rest against edge of fuel cup. Push on insert at both sides of steam until seams butt against each other, Fig #2. 4. Reinstall tank and new gasket on engine. CS.5 FILTER ADAPTER: Filter adapter may not be funneled or tapered. Top of filter adapter must be flat. Adapter may not be run without an air filter. No sealer between carb and filter adapter allowed.
CS.5.1 Adapter may have rolled edge not to exceed .250” from top.
CS.5.2 Maximum thickness of filter adapter is .250”, measured from the top of filter adapter to carb air horn mating surface.
CS.5.3 One Briggs and Stratton stock gasket may be used under filter adapter, maximum thickness
075”. CS.6A CONTROLLED CLASS ALTERNATE CARBURETOR: Tillotson model number 357 B with any manifold , Fuel pump and external tank to be accepted as an alternate to the stock Pulse-a-jet carburetor. Any commercially available manifold may be run.
** Note ** WFMT requires matching Manifold part number EC-440
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CS.6 CONTROLLED CLASS CARBURETOR: Must be Briggs and Stratton stock appearing carburetor and must have stock dual pick-up tubes. No material can be added to inside or outside of carb. No additional holes can be drilled in the “body of” carb. “Area behind jet no a tech item”. Both pick up tubes must work. Air must enter carb at air horn ONLY. One or two gaskets allowed. Only one gasket allowed when Blue-O-Print gasket is used. No sealer allowed on carb to block. Any attempt to bypass, gasket, bolts or bolt holes is prohibited. The butterfly must be held in place on throttle shaft with a screw. No other way of attaching is allowed.
CS.6.1 Maximum bore at .715”. (Full-length of bore) The carb bore is from the recess on the flange end (end that bolts to block) of the carb to the backside of the throttle shaft. Must be able to see some of the lip at between the recess area and the bore.
** Note ** in 2007 MRL allowed .750 bore at Wall Township Speedway Only.
CS.6.2 Diaphragm side CANNOT be used to create a pressure fuel feed. Diaphragm side of carburetor parts MUST be installed as supplied from the factory. Diaphragm cover plate MAY be surfaced to ensure a proper seal. No silicone or other material may be applied to diaphragm side of gaskets. After-market diaphragms, (including Teflon pumper diaphragm), allowed as long as it is of similar material and configuration of Briggs & Stratton diaphragm.
CS.6.3 Breather tube must be removed from carburetor. The hole in the carburetor may be plugged.
CS.6.4 A tab to reinforce a broken tank bolt on the carburetor-to-tank flange of carburetor is allowed.
CS.6.5 No after-market coatings are permitted.
CS.6.6 Remote mechanical carb adjusters legal in all stock classes.
CS.6.7 Holes left after removal of choke and threaded hole at floor of air horn may or may not be plugged so long as plugging does not protrude into air-horn area.
CS.6.8 Felt or foam washer must be on carb shaft under lever. Rubber seal must be in proper location in carb body for air seal around throttle shaft.
CS.7 HEAD BOLTS: Any stock head bolts may be utilized and eight are mandatory. Head bolt with stud allowed.
CS.8 CYLINDER HEAD: Stock Briggs & Stratton 5HP cylinder head required. Head cannot be machined below the flat cylinder portion of the head. Machining of two pockets for valve clearance or a single, continuous relief area from side-to-side across valve area is permitted. In no instance may the relief area touch either the back or sidewalks of the head and should be done in a manner not to affect airflow. Head may not be O-ringed. Recess at deepest point of cylinder head must be a minimum of .400° (from gasket mating surface).
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CS.9 HEAD GASKET: Briggs & Stratton production head gaskets are approved and aftermarket gaskets of general stock configuration (accommodates all head bolts, follows general stock pattern; does not extend to form “heat sink,” etc.) are acceptable. Gasket sealer must NOT be utilized o head gasket. NO aluminum or Copper gaskets allowed. (See Fig. 701.9)
CS.9.1 Head gasket must be a minimum of .043” thickness at four points between head bolt holes, front, near and both sides.
CS.10 CYLINDER BORE: No circular or machined grooving of cylinder is allowed in any position of cylinder (See Fig. 701.14.1)
CS.10.1 Stock cylinder bore is 2.5625” and overbore is permitted providing it does not exceed 2.6025” (approximately .040” overbore).
CS.11 CAMSHAFT: Cam can e of the type centered on each weld. Maximum running lift .265” no visual tech on lobes. Gear must remain as cast.
CS.12 BREATHER VALVE: Crankcase breathers are allowed.
CS.13 VALVES: Stock valves ONLY. No Stellite type valve allowed, as found in industrial style engines. Must be one angle ONLY. Valves may not be polished or lightened. If working are (that portion of the valve stem translating with the valve guide area) of valve stem is cleaned, no material may be removed, such as linear grooves, cross hatching, etc. (See Fig. 701.11)
CS.13.1 INTAKE VALVE: 30 degrees. Intake valve minimum diameter is 1.115”.
CS.13.2 EXHAUST VALVE: 45 degrees. Exhaust valve minimum diameter is .990”.
CS.13.3 Minimum thickness of valves between top (flat area) and seating surface to be minimum .035” (no “knife edging” of valve allowed). Valves will be checked with a NO-GO gauge for head thickness and legality will be determined by that gauge.
CS.14 VALVE SPRINGS: Optional, including retainers. Back facing of upper portion of valve chamber to stabilize valve spring retainers and prevent spring bind is allowed.
CS.15 VALVE SEATS: Valve seats must meet stock specs and can be replaced. Seats must have one angle only, 30-degree intake and 45 degree exhaust. Seats MAY NOT PROTRUDE above block casting or deck surface. PIN PUNCHING may be used to tighten a loose valve seat. No more than eight approx. evenly spaced pin punches per valve seat (see fig. 701.13 for locate and placement of pin punches). When re-facing valve seats it must be understood that if the tool for checking valve seat height enters valve seat, legality will be determined by that gauge.
CS.15.1 Intake seat inside diameter, 1.004” (NO-GO).
CS.15.2 Intake seat maximum thickness .215”. Minimum thickness .199”.
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CS.15.3 Exhaust seat inside diameter, .880” (NO-GO).
CS.15.4 Exhaust seat maximum thickness .215”. Minimum thickness .199”.
CS.16 DECK/PISTON CLEARANCE: Pop up not a tech item except Decking of the block cannot extend into the aluminum at rear of block (top of tin.)
CS.17 IGNITION: Briggs & Stratton factory stock coils are MANDATORY and must be utilized in unaltered form (see photo). NO slotting of mounting holes or machining of attaching bolts is permitted. New style composite ignition is allowed. There must be resistance from ground to the plug wire. SPAR PLUG CONNECTOR must be stock factory type. Rubber plug boot is allowed. May be run with or without air vane (See Fig. 701.18).
NOTE: Coils may be rechecked for correct ohms reading after 2 minimum at 10 minutes.
CS.17.1 Resistance from plug wire must be 2,000 ohms MINIMUM and 6,000 ohms MAXIMUM.
CS.18 STARTER: New style recoil starter may be retained as produced and intact, however, if new style coil is removed, starter cup must also b removed. Old style recoil starter must be removed. If removed, crankshaft may be cut-off to facilitate any style nut and use of electric starter.
CS.19 FLYWHEEL: ONLY stock, 5HP flywheel is permitted. Any flywheel key or NO flywheel key is allowed. Painting and coating of the flywheel (other than minimal factory over-spray) is not permitted. No machining, glass beading or sandblasting of flywheel is allowed. Chipped ins because of poor casting are allowed. However, completely broken fins are NOT allowed. Any screen or guard that fully covers the flywheel fins is allowed EXCEPT NO revolving screens. All screens must be bolted to blower housing. Flywheel washer must be stock
CS.19.1 Weight of flywheel shall be 6lbs 4ozs MINIMUM.
CS.20 CRANKCASE SIDE-COVER: Side-Cover must remain stock EXCEPT block and side-cover may be pin-punched to help prevent side-cover gasket failure and stub for governor may be removed and hole plugged to prevent leakage. Crankcase breather allowed.
CS.20.1 After-market gaskets approved, however, must be same size and material as stock gasket(s). Up to three crankcase gaskets are allowed. Block and side-cover may be pin-punched to help prevent side-cover gasket failure. Fel-Pro Multi layer crankcase cover gasket is allowed for all classes.
CS.21 VALVE LIFTERS: Optional. No titanium lifters allowed.
CS.22 VALVE SEAT HEIGHT: Install a .500” rod in place of the cam and replace side cover. Measure through the valve guide from top edge of .500 rod to the top of the surface of the intake or exhaust valve seat. Minimum 5.485” / Maximum 6.520”. Aluminum may be removed from top of seal to check seat height. Lifter bore and valve guide bore must except seat height gage rod.
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CS.23 CONNECTING ROD: After-market connecting rod may be used, but must meet stock specs No .020 undersize rods allowed. No under-sizing of connecting rod is permitted. However, rod may be clearanced providing that it is in stock configuration and finish with no “dimpling” or media blasting. Rod ends must be concentric with crankshaft journal end/or wrist pin with no chamfer or breaking if edges. Raptor III rod & dipper is legal: Dipper on Raptor III rod may be broken. However, it must be a natural break with no grinding, polishing or bead blasting visible. Old style rod (after market dipper) is a non-tech item in all classes.
CS.23.1 Stock rod length is 3.120” minimum , 3.1333 maximum. Measured from bottom of wrist pin to top of crankshaft journal.
CS.23.2 Oil hole opening. Raptor 3 or old style rod, is .185” NO-GO. New style cast Briggs & Stratton Raptor connecting rod approval (Part #555207). Oil hole and Chamfer no-go size to be established.
CS.24 WRIST PIN: Wrist pin must not be altered and must be stock Briggs and Stratton pin.
CS.24.1 Maximum inside dimension of wrist pin is .290”.
CS.24.2 Maximum outside dimension of wrist pin is .490”.
RAPTOR WRIST PIN SPECS
CS.24.3 Maximum inside dimension of wrist pin is .291”.
CS.24.4 Maximum outside dimension is .490”.
CS.24.5 Length 1.732 + OR .490”.
CS.25 RINGS Three rings are MANDATORY. Compression or top ring, if chamfered, may have either a beveled or chaffered inside face and must remain as manufactured. Scraper or second ring may only have an external circumference relief area. End of rings must remain flat. Mandrel check is no longer required. New factory rings from Briggs & Stratton without bevel on top ring and with relief around circumference of second ring are permitted. Excessive and gapping of rings not allowed. New style, beveled top compression ring (factory produced) is approved. Rings must conform to all listed factory specifications and be of stock configuration. Known, standards for piston/ring configurations and Briggs & Stratton factory approved parts. No machining of rings allowed. Exception; lapping and end gapping allowed, Shrinking of oil ring and low tension ring allowed. Rings must be in one piece when removed from block. With the exemption of the Raptor III oil ring, all broken pieces must be present in the ring land, if not the ring will be illegal. If stock rings are used they must meet the following specs.
CS.25.1 Top two rings, .105” minimum width (for wear).
CS.25.2 OIL RING must have minimum .085” width (for wear). Grove and six oil relief slots MUST be present on oil ring Groove must measure .083” minimum, regardless of condition of ring.
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CS.25.3 End gap with rings compressed on ring gauge cannot exceed .500”. CS.25.4 Top ring cannot exceed standard Briggs and Stratton ring land width of .084 maximum. RAPTOR III RINGS SPECS CS.25.5 Minimum width top two rings .090”. CS.25.6 Thickness top two rings .058” + OR -.005”. CS.25.7 Oil ring minimum width .070”, ring groove must be present. CS.25.8 Oil ring Thickness .100” + OR - .005”. CS.26 PISTON: After-market piston and stock rings may be used. No excessive cleaning oil top or
skirt of piston allowed Piston Pin must be Briggs and Stratton Stock. Wrist pin hole must not be altered or relocated, minimum honing of wrist pin hold allowed, NO matching is allowed on piston. If stock piston is used it must meet the following specs.
CS.26.1 From top of piston to wrist pin bore .937” minimum measurement CS.26.2 Minimum piston length is 1.869”. RAPTOR III PISTON SPECS CS.26.3 From top of piston to wrist in bore .937” minimum measurement. CS.26.4 Minimum piston length is 1.671”. CS.26.5 Top two-ring land width .0603” .0612”. CS.26.6 Oil ring land width .1020” .1032”. CS.27 CRANKSHAFT: Stock factory crankshaft mandatory. Stock factory timing gear mandatory
and must be installed properly. Lightening, polishing of counter weights, addition of metal o other material is not permitted. Hardening of stock crankshaft is permitted in all classes to reduce premature journal wear. The power takeoff journal of a sleeve-bearing cranskshaft may be machined (turneddown concentrically) to permit its use in a ball bearing block. Offset crankshafts are not permitted. After-market bearing of non self-aligning type, with or without shield, is permitted. NO STROKER CRANKSHAFTS ALLOWED. (Se Fig. 701.28).
CS.27.1 Minimum crankshaft journal diameter is .990”. CS.27.2 Crankshaft may be clearanced to a minimum dimension of .775” to permit easier removal of the bearing.
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CS.27.3 STROKE: Stock stroke is 2.4370” plus .007” or minus .010” for wear. Stroke is checked by pushing piston down to take up play of rod clearance. Stroke is checked from bottom dead center (BDC) to op dead center (TDC). (See Figure 701.16).
CS.28 PORTS: Porting Allowed. Ports surfaces are non-visual tech item. NO ADDITION OF MATERIAL ALLOWED. Block MAY NOT be machined or altered on intake or exhaust port “gasket mating” surfaces. NO GRINDING is allowed on underside of valve seat. No HOLES in ports allowed. If port is pin-punched, it may not be done in a manner to prevent entry of a NO-GO into port area. (See Fig. 701.29).
CS.28.1 Intake port .880” NO-GO.
CS.28.2 Exhaust port 1.005” NO-GO.
CS.29 BLOCK : Must be as produced, with no alterations or reworking, except block can be relieved for red clearance. Blocks repaired from broken rod damage, cracked lifter area, etc., are permitted providing that repair does not constitute a functional modification of original block. Porting of intake and exhaust ports allowed but block may not be machined on intake or exhaust ports gasket surfaces (See fig. 701.29). No bushings of any kind allowed except for bushings approved in this Tech Manual. DU Bearing may be installed in conventional block on flywheel side. Extra oil hole, 1/8” in diameter, may be drilled on flywheel side of block at crankshaft bushing to better lubricate crankshaft (applicable to all classes). Sleeving of cylinder block is permitted in all Briggs and Stratton engine classes. Regular ferrous sleeves only, with no coatings or plating, such as NicaSil, allowed. The repair of one coil post is allowed, as long as the remaining post is factory and unaltered. Valve guides may be replaced. Aftermarket valve brass or bronze guides allowed as long as they meet stock requirements. Valve guides may be stacked, No KNURLING of guides allowed. Minor grinding of block behind seal in a double bearing block where crank goes through block is allowed (to prevent crank from seizing). Chaffering at bottom of lifter bore for clearance purposes only allowed. Diameter of chamfer cannot exceed .500 and will be checked with a .505 no-go gauge, which measures .505. This applies to stock blocks that have been welded for strengthening purposes. No Undercutting of lifter bore permitted.
CS.30 WELDING: No welding can be done to an engine from the cooling fins upwards except minor welding to lower exhaust bolt hole is allowed for repair (weld cannot protrude into exhaust port). The only welding permitted is to repair damage from a broken rod or cracked lifter bore. Welding of lifter bore for reinforcement or breakage allowed. Installation of bushing guide to help reinforce lifter bore area allowed.
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Microstock Racing League Date location Event Sign in sheet Car Number Drivers Name Car Owner Pre Race Tech Heat Start Position Feature Start Position Feature Finish Post Race Tech
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