Limited Modified Rules
Mid-sized GM 1978-1987 metric full frames only with 108” wheel base as per OEM
specifications of stock. All frame bolt holes must remain in stock location. Wheelbase
will be checked with a minimum of 107” and maximum of 109”.
2350 lbs. minimum
602 Crate engine ONLY can utilize a 650 cfm Holley carburetor P/N 80541-1
You may only run (1) carburetor on intake.
Chevrolet: Quadrajet, Chevy two barrel, Holley #4412, or #0-80583-1 two barrels.
Ford: Motorcraft two or four barrel, Holley #4412, or #0-80583-1 two barrels.
Mopar: Carter or AFB two or four barrel, Holley #4412, or #0-80583-1 two barrels.
Carburetor spacer/adapter is allowed, but must not exceed 1-1/4 thickness including
Carburetor must be stock and unaltered with only one exception; circle track floats may
be used. Holley must have choke horn attached.
No Edelbrocks or similar hi-performance carburetors allowed.
Only 283, 302, 305, 307, 327 and 350 blocks can be used for Chevrolet. No big blocks.
Only 260, 289, 302, and 351 blocks can be used for Ford. No big blocks. OEM only.
Only 273, 318, 340, and 360 blocks can be used for Mopar. No big blocks. OEM only.
All casting numbers must remain on blocks. No side bolt main blocks allowed.
No Pontiac, Oldsmobile, Buick, Rambler, Studebaker, etc., motors. We realize some of
these cars came with Chevrolet motors, but casting numbers will bear this out and those
Chevy motors will be legal.
No 400 small block or big block crankshafts allowed. No in-lines. V-8’s only.
Again: Only Ford, Chevy, and Mopar engines are allowed.
Mopar=Chrysler, Plymouth, and Dodge. 370 cubic inch maximum.
Ford=Pontiac, Buick, Oldsmobile as long as they are Chevrolet engines. 368 cubic inch
No tolerance on cubic inch.
Compression may not be over 180 lbs. per cylinder on any cylinder. Tracks discretion on
cylinders checked. No tolerance.
Pistons may be forged, must be stock appearing and 10 ½- 1 flat-top, 4-valve relief must
have full OEM size skirt and be press fit. Two-valve relief piston will also be permitted
since compression rule is in effect. NO LIGHT WEIGHT OR FULL FLOATING
Decking block okay.
OEM blocks okay. No dart or after market blocks. No aluminum. Cylinder sleeves
okay. Polishing lifter galley okay.
Stock OEM rods, or (stock appearing- no light weight and must be of “I-Beam” type).
No aluminum. Chevy = 5.7” length maximum rods. No floating pistons.
OEM cranks only, steel or cast. Will allow stock appearing cast crank-shafts. Crank
shaft cannot be lightened, no aerowing, bullnose, knife edge, undercut or drilling of
second or third rod throws allowed. Must be stock stroke for engine used.
After-market rod, main and head bolts or studs allowed. Push rods may be any length.
Stock or circle track pans allowed. No dry sumps. No gas ported pistons. No accu.
Fluid dampener harmonic balancers are allowed. No roller rod, main, or cam bearings.
Cast iron water pumps only, except Ford and Mopar may be aluminum. OEM type only.
Mechanically belt driven only!
Stock OEM cast iron intake is required. No marine or Bowties. No tall intakes.
May use one of the following after-market aluminum intakes: Weiand GM #7547-1; Ford
#7515, #8023 or #7516; Chrysler #7545; Edelbrock GM 2701.
Ford may use aluminum, but no hi-rise or air under intake.
Mopar intake is same as Chevrolet.
No Brezenski, porting, polishing, acid dipping, or anything similar allowed. No hi-rise.
After market starters okay. Must mount in front of bellhousing.
Power steering pump and reservoir must be a one-piece unit. Must mount in front of
Steel side engine mounts may be of the 45 degree style or stock style.
Engine mid-plate is allowed and may be aluminum.
Any brand of air cleaner is allowed. No forced or RAM air allowed.
3.48 stroke maximum for Chevy. Balancing okay.
Engine displacement can be checked by pump even on protest.
Oil filters must attach at factory specs. No Oberg, etc. U. Polydyne coating or similar
Must have 1” sight plug in oil pan between the second and third pan bolt on the drivers
May use GM crate motor #88958602.
GM part number 88958602 only.
Sealed engine and GM factory seal bolts must remain intact and not show any evidence
Any seal that is broken or shows evidence of tampering will disallow the engine.
The penalty for tampering, removing or modifying any of the parts of the engine may
include suspension for up to one year, and/or loss of accumulated points and/or loss of
purse and point fund monies.
Vacuum pumps NOT allowed.
Hydraulic lift cams only. No maximum lift. Engine must pull 12” of vacuum at 1200
rpms. Timing or carburetor may not be altered at time of tech, if vacuum used. Must
have vacuum fitting in the intake (carburetor fitting not acceptable). Tech by vacuum
will be final. No hydraulic roller cam or lifters. No bushings in the lifter bore. Up to
four bushings will be allowed for repair. Hydraulic lifters only. No solid lift cams or
solid lifters allowed. Anti-pump up lifters okay. No gear drives. No reverse rotation
cams or motors. OEM rotation only. No vacuum cams of any type allowed.
No porting, acid dipping, or polishing allowed. Screw-in studs and guide plates are legal.
Stock diameter springs only for heads used. Stock type rocker arms. Any ratio. Ford
rocker arms on Chevrolet okay.
Flat milling okay. No angle milling.
Full roller rocker arms or roller tips are not allowed. No aluminum.
No aluminum or titanium components allowed. No carbon fiber parts anywhere.
Poly-locks are allowed. Heads may be cut 360 degrees under valves in bowl area only.
No stud girdles. 1, 2, 3, 4, and 5 angle jobs are legal.
No jesel or other assemblies allowed. No O-ringing block or heads.
Any breather/valve cover configuration/composition allowed.
Due to Fords and mopars having no cc rule, neither will Chevys.
May use Engine Quest (EQ) stock replacement cylinder head, part number CH350I, head
must remain as produced, seat angles and valve sizes cannot be changed; 3 angle valve
job only (absolutely no casting removal in valve pocket of EQ head for any reason)
Only these casting numbers can be used: 997, 445, 882, 624, 441, 487, 993, 185. These
are the last three digits and they are the only ones legal.
No valves larger than 1.94” intake or 1.5” exhaust. May remove smog clips inside
exhaust ports. No X-heads.
Any cast iron head. OEM Ford heads only. Headers listed for Ford are the only headers
that can be used. If the headers don’t fit the head you are using, head is illegal.
No boss or after-market heads of any kind.
No valves larger than 2.04 intake or 1.70 exhaust.
Mopar: Heads-Plymouth, Dodge, Chrysler
Any cast iron head. OEM Mopar only. Headers listed for Mopar are the only headers
that can be used. If the header doesn’t fit head you are using, head is illegal.
No after-market heads of any kind.
No valves larger than 2.04 intake and 1.70 exhaust.
Mopar can use the rocker arm bars. OEM only. No roller tips.
Back of entire flange must be mounted at a minimum of 70” forward of the centerline of
the rear axle. This will be measured on the passenger side of the car.
Minimum engine height is 11” from the ground to the center of the crankshaft. This will
be measured on the front of the crankshaft/pulley.
All cars must have ignition switch clearly labled.
Ignition switch must be located within reach when standing outside the car(easily
accessible to emergency personnel).
Stock or stock style ignition only. Ford may use Motorcraft, including box. Mopar may
use Mopar, including box. HEI legal on Ford or Mopar.
HEI must remain in one unit, no external coils allowed, unless you are using dual or
single point distributor.
MSD or any module may be used as long as it fits inside the distributor with no
alteration. Vacuum advance may be removed and the pick-up coil locked.
MSD, any brand, or GM electronic boxes are not allowed. No magnetos.
Only (1) 12-volt battery is allowed and must be securely mounted. Subject to tech
inspection. Battery may be charged by an alternator.
Headers- any 1 5/8” tube 4 into 1 with 3” collector one piece header. No 180 degree or
step header must bolt directly to the head with no modifications or adapter.
Only (1) radiator is allowed. It may be aluminum. Radiator must be mounted in front of
engine. Maximum size; 27” X 19”.
Racing radiator cap is allowed. Electric coolings fans are okay. May not have water
outlets to spray on radiator. Catch cans required.
Gasoline only. No oxygenated or other performance enhancers. No alcohol or nitrous.
Racing gasoline allowed.
No electric fuel pumps. Only stock mount push rod activated Holley and Carter style
allowed. No by-pass fuel systems, pressurized, or return lines allowed. No regulators of
any type. Lever type fuel pumps only.
Maximum 22 gallon fuel cell. Fuel cell with a roll over valve is required. Must be
securely mounted inside trunk area only, must be between frame rails, and must be totally
enclosed from the driver compartment. A minimum of (2) fuel cell straps required to
secure fuel cell. Fuel cell protection bar required. Must be a minimum of 1 1/2” X 0.95”.
it must protect the fuel cell from the rear. It must be as low as the fuel cell, and extend
from side to side as wide as the fuel cell. It is recommended that this bar be attached to
the frame, not the bumper. If the fuel cell protection bar is not present, the car will not be
allowed to continue running.
Drive Train- Transmission:
Any OEM automatic transmission is allowed. Must have a working torque converter,
minimum of 10”. No direct drives, couplers, valved pumps, or bleeder style valve
bodies. Automatics must have at least (1) forward gear, and reverse gear must be in
working order. Ford may use GM or Ford automatic. Mopar may use GM or Mopar
automatic. Chevrolet must use GM automatic. Stall converters okay.
Standard transmissions must be stock with all gears in working order, with minimum of
10.5” clutch, pressure plate and steel flywheel. No mini-clutches. May not use
aluminum flywheel. Ford clutch is 9” minimum.
All standards must have bell housing made of ¼” thick steel or cast iron and cover 180
degrees over the sides and tip of the clutch assembly. Slave cylinders or hydraulic throw
out bearing okay.
3, 4, or 5 speed manual transmissions only, OEM only. No Bert or Brinn type
No ram couplers.
Quick change transmissions or transmission adapters for gear change are not allowed.
Car must be self-starting and have working neutral, reverse, and forward (with engine
running and car in a still position must be able to engage car in gear and move forward,
Transmission fluid coolers are allowed.
No aluminum converters. Flywheels and converters can be checked with magnet.
Converters can be checked by moving car forward and backwards to check stall.
Cars MUST idle in all gears.
Drive shafts must be steel, and must be painted white or silver. Must have steel drive
shaft loop (360 degree) connected to the frame located within 6” of the front drive shaft
u-joint. Minimum size is 2” X 1/8”.
Rear end housing must be stock 7.5” GM 10 bolt. Bracing optional. Snouts on end of
7.5” rear end can be modified to accept 9” Ford axle. Stock mounts on lower trailing
arms must remain in stock location on original 7.5” tube housing. No 3” tube from center
section out to mounts on trailing arms. After-market axles, studs, and mini-spools are
allowed. No posi-trac, limited slip style rear ends. Rear end axles must be locked
together at all times. C-clip eliminators are allowed. Cups may be placed on housing for
Any gear ratio may be used, if no alteration to housing is required.
Bolt pattern on the axle/drums may be changed. Pinion angle may not be altered. No full
spools, Gold Track, or aluminum spools of any kind. Stock width unless using Ford
axles. If Ford axles are used, rearend must not be narrower than stock nor more than 3”
C-clip eliminators and disc brakes are allowed and recommended to eliminate axles from
No floater rearends of any type. No 9” Ford or 8.5” rearends allowed. 7.5” only.
Single or dual master cylinder after market brake pedal is allowed, or dual pedal with
adjuster okay within driver’s reach. Rear brakes must be drum or disc up to 12” disc
brakes. Steel only. Hats and steel rotors are legal on rear ends only. Hats must be steel.
No single phase rotors allowed.
Minimum of (3) working brakes is required. If using (3) brakes, the fourth brake
components need not be present. Wheel shut-off valve must not be in driver
compartment. Spindle must remain unaltered.
Cooling holes may not be drilled in any brake components.
No aluminum brake components allowed.
Quick release steering wheel is mandatory.
Quick steer is optional. No chains or sprockets allowed in the steering system except
D & M quick steer.
Steering left of drive train only. This means drive shaft.
Bump steer cannot be adjusted. Center link, inner tie rods, outer tie rods, or sleeves
cannot be altered (must be OEM and in OEM stock location).
Power steering is allowed. Steering pump and reservoir must remain one unit.
No rack and pinion steering. Stock OEM steering gear box must be used. May not be
Idler arms must remain in stock location.
IMCA TUBULAR UPPER CONTROL ARMS WILL BE PERMITTED (steel only
and must be IMCA stamped, non-adjustable).
No traction control of any type.
Upper control arm brackets may be moved for caster and camber adjustment. Can not
move lower A-frames. Must use stock lower control arms and brackets. Upper mounts
may be modified, but must remain stock material.
Upper and lower control arm bushings may be after-market.
Sway bars (may be removed) and brackets must remain stock. Bushings may be after-
Racing springs are allowed. Steel only. No coil-overs. No jack bolts allowed.
Adjustable spring buckets are allowed. May drop rear spring buckets as long as they are
in stock location.
Spindles and rotors must remain stock for 1978-1987 metric frame w/108” wheelbase.
Ball-joints must remain stock appearing (may be welded in). no grinding or lightening
parts. Bolt on spindle savers are legal.
No welding on spindles. Reaming spindles for ball joints okay.
No drilling cooling holes in rotor. 5’8” studs are allowed in any bolt pattern.
All four rear trailing arms must retain stock arms for metric frame used. Must remain
stock in length. Must not compress or lenthen. Arms may be boxed or strengthened.
After-market bushings may be used. No spherical or ball bearing or Timken bearings
anywhere on the cars suspension.
No suspension parts may be altered or lightened.
No aluminum parts allowed, other than bushings.
Each trailing arm must have bushings installed and in good working order.
Lower A-frame mounts may be notched for clearance.
Shocks must be steel. Must use stock type shock ends. May weld or screw stock ends on
The stock shock frame mounts must be used in the original stock location.
One shock per wheel. May use spacers when mounting shocks.
Air shocks not allowed.
Frame can not be cut, bent, or altered to change suspension brackets, except upper control
arm brackets on front end.
Front frame horns can be cut off in front of the steering box and idler arm.
Rear frame rails may be cut off behind upper shock mounts.
Replacement may be made with round, square, or rectangular tubing.
Front frame may be cut for radiator clearance.
Frame may be cut for seat clearance.
You can not cut holes in frame to lighten it. Rust may be removed, in front of lower rear
trailing arms and cleaned up on body mount holes.
Frame can not be widened, narrowed, shortened, or lengthened.
Cross member mounts on frame for transmission may be removed, but cannot be farther
forward than welds on frame.
If weights are used for ballast, weights must be painted white and number of car must be
on weight. No mercury ballast or any similar type of ballast may be used. All weight
must be securely fastened. Loss of weight will be cause for disqualification.
Main roll cage must consist of continuous hoops not less than 1 ½” X 0.95”. All welds
must be complete. No brazing or soldering. No part of main cage may extend forward
past rear motor plate. The main roll bar must not attach to the frame rearward of front
edge of the rear tire.
Main roll bar and halo must be a minimum of 1” above the drivers helment.
A minimum of (3) drivers door bars, and (2) passenger side door bars is required.
(4) bars, two per side, may extend from the main roll cage to the points on the main frame
in front of the upper control arms.
(6) bars may extend from the main cage to the rear, X-bracing is allowed.
Door plates are MANDATORY (minimum 4” X 12”).
Cages must be steel or chrome-moly.
One single nerf bar between the front and rear wheels on each side of the car is allowed.
Maximum size= 1 ½” X 0.95”. They are to be attached to the cage at the front and rear
sections of the nerf bar. No center supports are allowed on the nerf bar. Neft bars may
not be outside of tires. All bumpers and nerf bars must be capped.
Minimum of (3) windshield bars 5/16” in diameter is required. Must be mounted in front
IMCA or “H-stamped” Hoosier 500 – 8.0 / 26.0 -15 and/or 8.0 / 27.0 -15 Only. (The “H”
stamp will be the same as the IMCA tire from Hoosier and should be cheaper due to no
dues payable to IMCA) A durameter rule is pending. You may run your 2009 AR500 on
the front until May 1, 2010 to allow for a burn off period.
Only steel 15” X 8” RR bead-lock is allowed.
No wheel spacers allowed with stock studs. Any offset wheel allowed. 5/8” studs are
allowed. Wheel spacers may be aluminum.
One-inch diameter lug nuts are required. Wheel adapters will be treated as spacers and
may be aluminum. 1 ½” maximum on spacers.
Oil and transmission fluid coolers are not allowed in drivers compartment. Floor in
drivers compartment must be complete; therefore, there must be a floor pan under the
No upholstery allowed, other than drivers seat cover. No plastic in drivers compartment.
Roof rear sail panels are allowed one 90 degree bend along the top edge of the sail panel,
but must be less than 1” wide. No Gremlin style roofs.
No more than 6” of total rake allowed on the body deck. A maximum of 3” of rake (of
the 6” total) is allowed in the door section and a maximum of 3” of rake is allowed in the
quarter panel section. If you keep the door section level, then you are only allowed 3” of
rake in the quarter panel section.
Minimum ride height is 5” from ground to side frame rails.
Plastic body panels and plastic filler panels are not allowed.
No convertibles, unless special race.
Cars must have full deck interior from one side of the body to the other. Decks must be
aluminum or sheet metal.
Quarter panels must be 90 degrees to the ground, with a maximum of a 45 degree bend 4”
from the bottom of the doors and quarters and 2” on top.
Must be metal or aluminum sized holes for throttle, etc. Firewall must be sealed from
Must be metal or aluminum. Must cover entire drivers cockpit to front edge of seat.
(2) bar front bumper is mandatory. Maximum size is = 1 ½” X 0.95”.
One single bar rear bumper is required. Maximum size is = 1 ¾”. The required fuel cell
protection bar (maximum size = 1 ½” X 0.95”) may be attached to the rear bumper.
Must cover completely the top of engine and radiator.
Must extend from the nose piece to the deck.
Hood may be made of metal, aluminum, or fiberglass.
Hood must provide a seal to the top of the engine compartment.
Cannot cover side of engine more than 5”.
Hood scoops okay.
Rear spoiler is allowed, with a maximum use of material of 15”, measured along the
spoiler, from the deck to the top, not straight up and down. A maximum of four braces
are allowed, one on each side, measuring a maximum of the angled height of the spoiler
X 24” long. Only (1) spoiler is allowed. Aluminum or lexan okay. Spoiler may not go
beyond back bumper. NO SPOILER ON ROOF.
Driver Restraint System Seat:
Aluminum racing seats with right side rib protection required. A seat that provides both
left and right sight rib protection is recommended. Seat must be securely mounted. The
racing seat must be bolted to a reinforced cross member and bracket(s). This cross
member must be welded to the roll cage, not just to the floorboard. The back of the
seat must be supported and bolted to a flange that is connected to the cage.
Racing type 5-point seatbelts are mandatory. All 5 belts must be fastened while driver is
in car and on racing surface. Must be securely mounted with ½” bolts and tabs welded to
the cage or frame. Must be less than 5 years old. If the SFI tag is not present or is not
legible, the belts will be deemed illegal.
Window nets are mandatory. It may be mesh or web style. Sprint car cage net is
allowed. A quick release window net system must be used.
Must be an approved racing helmet in good condition. Neck brace is mandatory 360
degree or horseshoe style.
Driver suit (fire suit) mandatory, may be (1) or (2) piece, must be complete and be of fire
resistant material and in good safe condition. Fire resistant driving gloves and shoes are
Definitions: O.E.M. unaltered unlightened, Ford does not make OEM parts for GM and
Stock: OEM part. If it needs an adapter it’s not stock.
All rules are subjected to change at any time. Any rule infraction to be in question will be
at tracks discretion.