Limited Modified Rules

Mid-size 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”.

CARBURETOR: 602 Crate engine only can utilize a 650 cfm Holley carburetor P/N 80541-1

You may only run one 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" total thickness including gaskets.
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.

a) GM Part number 88958602 only.
b) Sealed engine and GM factory seal bolts must remain intact and not show any evidence of tampering.
c) Any seal that is broken or shows evidence of tampering will disallow the engine.
d) 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.
e) Vacuum pumps NOT allowed.

Only 283, 302, 305, 307, 327 and 350 blocks can be used for Chevrolet. No big blocks. OEM only.
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. No hemis.
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! This goes for Ford, Chevy or Mopar.
No 4-cylinders allowed. No V-6’s allowed. No in-lines. V-8’s only.
Again: only Ford, Chevy or Mopar engines are allowed.
Mopar = Chrysler, Plymouth and Dodge. 370 cubic inch maximum.
Ford = Ford and Mercury. 360 cubic inch maximum.
Chevy = Pontiac, Buick, Oldsmobile as long as they are Chevrolet engines. 368 cubic inch maximum.
No tolerance on cubic inch.

Compression may not be over 175 lbs. per cylinder on any cylinder. Track's discretion on cylinders checked. No tolerance.

Piston may be forged, must be stock appearing and 10 1/2 to 1 flat top, 4 valve relief must have full o.e.m. size skirt and be press fit. NO LIGHT WEIGHT OR FULL FLOATING PISTON. (these pistons are only legal in Houston area, not in IMCA, SIMS or UMP) Decking block okay.
OEM blocks only. No Dart or after market blocks. No aluminum. Cylinder sleeves okay. Polishing lifter galley, okay.
Stock OEM rods. Balancing okay. No aluminum. Chevy = 5.7” length maximum rods. No floating pistons.
OEM cranks only. Steel or cast. Balancing okay. No splayed main caps. No after market cranks.
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. sumps.
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 after market. No tall intakes.
Ford may use aluminum, but no hi-rise or air under intake.
Mopar intake is same rule as Chevrolet.
No Brezinski, 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 engine.
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 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 allowed.

Hydraulic lift cams only. Maximum lift = 450”. This may be measured at the valve or 12” of vacuum at 1200 rpms. Timing or carburetor may not be altered at time of tech, if vacuum used. It is the tracks discretion as to which way they want to check cam, even on the protest. Must have vacuum fitting in intakes. Tech by vacuum will be final. B. No hydraulic roller cam or lifters. No bronze bushings in the lifter bore or similar pieces. Up to four bronze bushings will be allowed in lifter bore for repair. Hydraulic lifters only! No solid cams or solid lifters allowed. C. Anti-pump up lifters okay. No gear drives. D. No reverse rotation cams or motors. OEM rotation only! E. 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 allowed. 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, or 5 angle valve jobs are legal.
No Jesel or other assemblies allowed. No O-ringing block or heads.
Any breather/valve cover configuration/composition is allowed.
Due to Fords and Mopars having no cc rule, neither will Chevy’s

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 1.50 exhaust. May remove smog clips inside exhaust ports. C. 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 204 intake or 1.70 exhaust.

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 or 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 crank shaft/pulley.

All cars must have ignition switch clearly labeled.
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 one 12 volt battery is allowed and must be securely mounted. Subject to tech inspection! Battery may be charged by an alternator.

EXHAUST SYSTEM:

headers. Any one and five/eights inch (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 one 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 cooling 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 is Allowed.

No electric fuel pumps. Only stock mount push rod activated Holley and Carter style allowed. No bypass fuel systems, pressurized, or return lines allowed. No regulators of any type. Lever type fule pumps only.

A. Maximum 22 gallon fuel cell. B. 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 two (2) fuel cell straps required to secure fuel cell. C. Fuel cell protection bar required. Must be a minimum of 1 1/2" X .095". 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.

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 one 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” inch clutch, pressure plate and steel flywheel. No mini-clutches. May not use aluminum flywheel. Ford clutch is 9” inch minimum.
All standards must have bell housing made of 1/4” inch 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 transmissions allowed.
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.
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 or fluorescent orange. 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 inch 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 springs only.
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" wider.
C-Clip Eliminators and Disc Brakes are allowed and recommended to eliminate axles from sliding out.
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 three working brakes is required. If using three brakes, the fourth brake components need not be present. 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 can not be altered.
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 moved.
Idler arms must remain in stock location.

May use IMCA stickered , limited replacement tube upper a arm steel only. also steel only cross shaft

No traction control of any type!
Upper control arm brackets may be moved for caster and camber adjustment. Cannot 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 market.
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 lightened 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 lengthen. Arms may be boxed or strengthened. After market bushings may be used. No spherical or ball bearing or Timken bearings after the 2003 season anywhere on 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 shocks.
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 cannot 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 cannot 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 cannot 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 most 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 1-1/2" X .095". 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 helmet.
A minimum of three (3) driver's door bars, and two (2) passenger side door bars is required.
Four (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. These bars may have two additional braces per side to the main frame.
Six (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 = 1-1/2" X .095". 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. Nerf bars may not be outside of tires. All bumpers and nerf bars must be capped.

Minimum of three (3) windshield bars 5/16" in diameter is required. Must be mounted in front of driver.

Hoosier 8.0 / 26.0 -15 -500 D and/or 8.0 / 27.0 -15 - 500 D. ONLY...
Grooving is okay. Siping is not allowed. (This means by razor blade or anything similar.)

Only steel 15" X 8" RR beadlock 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. D. Wheel adapters will be treated as spacers and may be aluminum. 1-1/2" inch maximum on spacers.

Oil and transmission fluid coolers are not allowed in driver’s compartment. Floor in Driver's Compartment must be complete; therefore there must be a floor pan under the driver's seat. (2007 Update)

No upholstery allowed, other than driver’s seat cover. B. No plastic in driver’s compartment.

A. 40" maximum

B. 107" minimum 109" maximum

C. 31" minimum 48" maximum

D. 23" maximum

E. 5" minimum

F. 31" maximum

G. 67" minimum

H. 35" maximum

I. 28" maximum

J. 41" maximum

K. 58" maximum

L. 5" maximum

M. 9" minimum 15" maximum

N. one 90 degree bend less than 1" wide

O. 32" x 32" minimum 53" x 53" maximum

P. 98" minimum 121" maximum

Q. 55" minimum 67" maximum (interior deck)

R. 15" maximum

S. 9" maximum (optional)

T. Max. 1-3/4" single bar rear bumper

U. 77" maximum

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.

FENDERS:
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 with minimum sized holes for throttle, etc. Firewall must be sealed from engine compartment.

Must be metal or aluminum. Must cover entire driver’s cockpit to front edge of seat.

Two (2) bar front bumper is mandatory. Maximum size is = 1-1/2" X .095".
One single bar rear bumper is required. Maximum size is = 1-3/4". The required fuel cell protection bar (maximum size = 1-1/2" X .095") 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 one spoiler is allowed. Aluminum or Lexan okay. Spoiler may not go beyond back bumper. NO SPOILER ON ROOF.

Aluminum racing seats with right side rib protection is required. A seat that provides both left and right side 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 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. Must be approved 3" wide shoulder straps, lap belts and a minimum of one 2" sub strap. All belt systems must be securely attached to the roll cage, or seat cross member and not to the floorboard. Seat belts must be in good condition.

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 one (1) or two (2) piece, must be complete and be of fire resistant material and in good safe condition. Fire resistant driving gloves and shoes are recommended.

Definitions: O.E.M. - unaltered unlightened , FORD does not make OEM parts for GM and so on.