Back to Rules index
IMCA Late Models
2013 Late Model 2011 Late Model rules PDF Revised October 2010. Revisions/clarifications underlined, recommendations italicized, amendments underlined and italicized (date amended). The rules and/or regulations set forth herein are designed to provide for the orderly conduct of racing events and to establish minimum acceptable requirements for such events. These rules shall govern the condition of all events, and by participating in these events, all participants are deemed to have complied with these rules. NO EXPRESSED OR IMPLIED WARRANTY OF SAFETY SHALL RESULT FROM PUBLICATIONS OF OR COMPLIANCE WITH THESE RULES AND/OR REGULATIONS. They are intended as a guide for the conduct of the sport and are in no way a guarantee against injury or death to a participant, spectator or official. The race director shall be empowered to permit reasonable and appropriate deviation from any of the specifications herein or impose any further restrictions that in his opinion do not alter the minimum acceptable requirements. NO EXPRESSED OR IMPLIED WARRANTY OF SAFETY SHALL RESULT FROM SUCH ALTERATION OF SPECIFICATIONS. Any interpretation or deviation of these rules is left to the discretion of the officials. Their decision is final. 2011 Late Model 1. SAFETY EQUIPMENT: Rules apply at all times car is on track. Snell-rated SA2000, SA2005, or SA2010 helmet required. Roll bar padding required in driver compartment (Fire retardant recommended). SFI-approved full fire suit required. Fire retardant gloves, shoes and neck brace (or head and neck restraint) required. Right and left seat head supports required if using head restraint system with no neck collar. Recommended: Fire retardant head sock and underwear; collapsible steering shaft. Driver-side window net required, minimum 16 inch by 20 inch ribbon or mesh style, and must be mounted to roll cage so latch is at top front of window. Minimum three inch (two-inch with head restraint system) wide SFI-approved five point safety belt assembly required (Y-type shoulder harness not allowed), must be mounted securely to roll cage, recommended to be no more than two years old. Kill switch required within easy reach of driver and must be clearly marked ‘OFF’ and ‘ON’. 2. FRAME: Must be constructed of two inch by two inch square steel tubing, or minimum 1.75 inch round tubing – with minimum 0.083 wall thickness. Minimum wheelbase of 103 inches, maximum 105 inches, both sides. 3. ROLL CAGE: Main roll cage must be at least 1.5 inch O.D. tubing with minimum wall thickness of 0.083 inches. Driver’s head must not protrude outside cage with helmet on. 4. DOOR BARS: Minimum three driver door bars must be at least 1.5 inch O.D. tubing with minimum wall thickness of 0.083 inches. 5. BODY (see body diagram for specific dimensions Late Model Drawing 2011): No composite body panels allowed except roof rock guard and hood scoop. No fins or lips anywhere along length of car. Maximum body width at bottom of doors is 82 inches. Minimum ground clearance is three inches. Must have IMCA approved stock-appearing nose piece (molded type material) mounted in approved manner. Headlight decal package required. No part of body can be wider than 90 inches. Roof must be stock appearing, mounted level, parallel to body, centered on car and rounded down in all directions. Maximum 1.5 inch rolled down rock guard allowed on roof front. Roof supports and window side panels must extend to edge of body. Window side panels must resemble all aspects of drawing – must have opera window and be same on both sides. Rear spoiler may be maximum eight inches in material height and maximum 72 inches wide. Spoiler may have stiffener, must be one inch or more down from top. Maximum of three spoiler braces allowed, must be mounted in line, and must resemble all aspects of drawing. No covers or inner panels allowed. No rear filler panel required. Car number must be minimum four inches thick and 20 inches tall and clearly visible, on both sides, top and back of car, and front, if possible. 6. DRIVER COMPARTMENT: Minimum three windshield bars in front of driver. Lexan or aluminum cowl panel in front of driver allowed, but can be no wider than cockpit and no farther back than steering wheel. Driver must be sealed off from track, driveline, engine, fuel cell, suspension components, battery, coolers, pumps, fuel and oil lines. Aluminum high back seats only, must be bolted in with 0.375 inch bolts. No mirrors. No driver-adjustable devices allowed while car is in competition except brake adjuster and right front brake shut-off. 7. FRONT SUSPENSION: Must be of A-frame or strut configuration. 8. STEERING: Rack and pinion steering allowed. Quick-release steering wheel required. 9. SHOCKS: Must be constructed of aluminum or steel. No covers. No remote-reservoir shocks. 10. SPRINGS: Coil springs must be steel. No covers. Leaf springs may be composite or steel. 11. REAR SUSPENSION: No independent rear suspension, any other configuration allowed. 12. REAR END: Quick changes allowed. No open tube or cambered rear ends. Rear end coolers allowed. 13. BUMPERS: Must be either capped, or bent forward at ends, no sharp edges. All cars must be equipped with tow hook or similar device front and rear. 14. TIRES/WHEELS: IMCA stamped Super Chain Link (SCL) Hoosier Race Tires only. 29 x 11 x 15 allowed. 28 or 27.5 x 11 x 15 ‘stagger tires’ allowed on left rear only. No softening, conditioning, or grooving (Refer to www.imca.com for automatic penalties). Grinding and siping allowed on tire tread only. 12 inch wide wheels only. Bead locks allowed on right side only. External bead lock only, cannot make wheel any narrower than 12 inches and no wider than 12.75 inches. Foam, plastic, or aluminum (must be bolted behind bead lock rim) mud plugs allowed on any wheel. 15. BRAKES: Must be operative and lock up all four wheels during any inspection. Steel brake rotors only. Brake shut-off allowed on right front only (electric or mechanical). 16. EXHAUST: Round tube headers only. All primary header tubes must enter directly into one collector, at same point, at end of header. No merge collectors. 17. FUEL SYSTEM: Any Holley four barrel carburetor, all external components (float bowls and main body) must be Holley manufactured. Metering blocks and base plate may be billet aluminum non-Holley. No aerosol-style carburetors allowed. No air dams or devices allowed to increase air flow to carburetor outside of air cleaner. Maximum two inch tall spacer between carburetor and air cleaner base. No cold air boxes, air cleaner duct work, or fuel cooling devices. No electric fuel pumps. Racing fuel cell required, maximum 32 gallon capacity, must be in minimum 20 gauge steel container. Must mount with minimum two solid steel straps around entire cell, two inches wide and 0.125 inch thick. Cell must be mounted between frame rails, behind rearend, bottom of cell can be no lower than center section. Fuel cell vents, including cap vent, must have check valves, and bladders are highly recommended. If fuel cell does not have aircraft style positive seal filler neck/cap system – a flapper, spring or ball type filler rollover valve is required. Fuel cell guard must come to bottom of fuel cell and be minimum 1.5 inch O.D. tubing. 18. FUEL: Gasoline only. No E85 allowed. No performance enhancing additives or pressurized fuel systems. Fuel must pass both dielectric meter and chemical tests for additives. Fuel sample may be taken from any car at any time (Refer to www.imca.com for automatic penalties). 19. WEIGHT: Must weigh minimum 2,350 pounds after race with driver. Weights must be painted white with car number on them. Must be securely fastened with minimum two 0.5 inch steel bolts, inside body panels, not on rear bumper. No weights and/or loose objects in driver’s compartment. Only carbon fiber components allowed are rock guard and hood scoop. 20. BATTERY/STARTER: Battery must be securely mounted to chassis, protected by tubing, and positive terminal must be covered. Starter must be in working order. Car must start under its own power. Car must leave initial staging area on demand, unaided, or go to rear of that race. 21. GAUGES/ELECTRONICS: No unapproved cameras, transmitting or listening devices (exception is one-way RACEceiver radio by officials), timing retard controls, or digital gauges (including tach). No electronic monitoring computer devices capable of storing or transmitting information except memory recall analog tach. All cars MUST use max 8,000 rpm rev limiter chip. This may be accomplished using one, non-adjustable, ignition box with one high-end rev-limiter setting or an internal setting inside box. MSD #8728 rev-control or MSD #8738 additional rev control box allowed. Preset Crane #6000-6480 ignition box allowed. No additional ignition accessories allowed. All components must be out of reach of driver, but accessible for inspection. No crank triggers. No electronic traction control devices (Refer to www.imca.com for automatic penalties). 22. TRANSMISSION/DRIVESHAFT: Must have at least two gears forward and one gear reverse, plus a neutral position. Must be able to put in and out of gear with car sitting still and engine running. No overdrive transmissions. All transmissions must bolt directly to back of bellhousing that bolts directly to engine block. Must use steel or aluminum driveshaft and be painted white. 360-degree drive shaft loop required, minimum 0.25 inch by two inch steel strap, or one inch tubing, mounted six inches back from front U-joint. 23. ENGINE LOCATION: Measured from centerline of upper ball joints to center of number one spark plug hole. Maximum setback is eight inches. 24. IMCA SPEC ENGINE RULES: (A) Steel blocks only. (B) Maximum 361 c.i. (GM), 362 c.i. (Ford) 364 c.i. (Chrysler). Minimum four-inch bore. Minimum stroke: GM – 3.48 inch, Ford – 3.40 inch, Chrysler – 3.313 inch. (C) Maximum compression – 10.5 to 1, checked at any time with Whistler. No tolerance. (D) Brodix/IMCA spec cylinder heads only. No grinding, polishing or altering of any kind. No use of any substance that may change or alter shape or size of ports, runners or combustion chambers. Only alteration allowed to heads are for push rod clearance and to install shaft rocker system. Maximum valve sizes are 2.08 intake and 1.600 exhaust. Valve seats and guides to remain as manufactured and in as-cast positions. Minimum combustion chamber size to be 62 cc volume. Valve angle to remain as manufactured. Approved cylinder heads as follows: • General Motors (i.e. small block Chevrolet) – Brodix # 46 221 • Ford Motor Company (i.e. small block Windsor) Brodix #46 223 • Chrysler Corporation – Mopar – Brodix #46 222 (E) No modification to intake manifolds, must be used as produced by manufacturer. All engines must run unaltered one inch carburetor spacer – Flow Design part #FD7060. Maximum 0.100-inch thickness gaskets only, one on top and one on bottom of spacer. List of approved intakes as follows: • General Motors – Brodix #HV100946 • Ford Motor Company -Edelbrock #2981 or 2980 (351) or #2921 (302) • Chrysler Corporation- Edelbrock #2915 (F) Camshafts may be of roller, flat tappet or mushroom design. (G) Crankshafts and connecting rods must be steel. One inch inspection hole required in pan – no obstructions to crank and rods. If obstructions are present, must remove pan for inspection. (H) Flat top pistons only. 25. ENGINE PROTEST PROCEDURES: Within 5 minutes after race, any driver starting feature may, for $300, protest (in writing) any engine. $100 of the protest fee goes to the track and will not be refunded, regardless of protest outcome. Driver may only make one protest per event, may not protest another driver finishing in a position behind them and may not protest same driver more than once per calendar year. One protest allowed per event, draw determines multiple protests. Under this protest, following MUST be inspected: intake manifold, cylinder head (removal required), bore and stroke, and visual inspection in oil pan. $200 will be returned to protestor if engine is found illegal. If engine being protested is found legal, $200 protest fee will be paid to driver being protested. If parts are found illegal, or if driver refuses to submit to protest, first infraction will result in forfeiture of all cash and contingencies, trophies and points earned in feature. Logo will be removed from heads, serial numbers will be recorded and all sanctioned tracks will be notified. Second violation will result in 30-day suspension from all IMCA sanctioned events and until such time as a $1,000 fine is paid to IMCA. Promoter may protest any engine. 26. POINT STRUCTURE/PROCEDURES: Refer to www.imca.com. 27. EIRI: (Except in rare instances) Decisions of IMCA Official(s) are final and binding without exception. In some cases, track safety rules may take precedence over IMCA rules – any discrepancy between IMCA and track rules should be brought to the attention of IMCA. Any rule changes or clarifications during the course of the year will be amended on www.imca.com, as well as published in Inside IMCA, the official newsletter of IMCA, and will be considered as an official part of these rules. For more information, call Tom Gutowski at 402-350-6120 or Josh McGowan – 319-310-3095. Copyright © 2011 IMCA. All rights reserved. No part of this publication may be reproduced, stored, or transmitted in any form, without prior written permission.