Pro4s

Bodies:
American and Foreign four passenger hardtop production cars from 1968 to the present. Stock appearing body, no wedge type nose, rear tail panel must be closed. Stock snout only. Any car not snouted will use Chevy Monza, Ford Pinto, Ford Mustang, or Chevy S10 pickups. No front wheel drives.

Weight:
All classes will be weighed with drivers strapped in, after finish of race. No filling up with gas on regular race meets (only on races of 51 laps or more). Dislodged weight will not be returned to car for weighing after the race.
Tube chassis 2350 pounds. 54% left hand weight with driver at finish.
50 pound weight break for leaf springs.
50 pound weight break for 2000cc engine.
Full stock floor pan 2150 pounds.
Minimum no exceptions. 56% left hand weight with driver at finish.

Engine:
4 cylinder. No V-4's. 2500 CI maximum for Chevy only. Up to 2300 for Ford. 2400 for Toyota.

Block:
Stock steel. No angle milling of blocks or heads allowed. No strokers. Must pass Tech tool.

Crank:
Stock for block used(Ford for Ford, Chevy for Chevy, Toyota for Toyota). Steel or cast stock stroke.

Rods:
Steel. Maximum 5.7 length ford. toyota can add .500 to rod length also.

Cam:
Flat tappet. No rollers. .450 lift maximum

Heads:
Stock head. No SVO High Performance, Limited Production, or Super Duty.
NO Porting and Polishing allowed.
No double overhead cam engines.
Gasket matching only

Bore:
.40 over.

Carburetor:
Holley 4412 500/500hp p/n 80583 two barrel.
No alteration.
No fuel injection or pressure fuel systems (EFI).
No electric fuel pumps.oil preasure shut off switch mandatory.

Pistons:
Any flat top.

Manifold:
Stock for engine.

Spacing:
1" spacing allowed between carburetor and intake. No taper, straight thru only.

Ignition:
Any OEM battery fired. No mag's or MSD.

Rockers:
Stock only. No roller or roller tips.

Lifters:
Stock bore only. No roller.

Balancing:
Allowed.

Oiling Systems:
Enlarged oil pans allowed. No dry sumps. Oil coolers allowed.

Brakes:
Steel rotors, single pistons, aluminum calipers.

Engine Location:
Stock locations to #1 spark plug even with ball joint, will be maximum allowed.

Drive Shaft:
No aluminum.

Frame Clearance:
Three inches all around the car, including ballast without driver.
Tow points front and rear MANDATORY

Wheel:
7" or 8" Steel wheels only. All wheels will be same diameter. Oversized lug nuts on all four wheels.

Wheelbase:
Maximum 102".

Tires:
Any 13” treaded racing tire allowed

Tread width:
60" +/- ½" allowance. For each 1" over tread width, 50 pound penalty will be added.

Shocks:
One shock per wheel. No air or adjustable shocks allowed. Steel only.

Rear Ends:
Gears 600 maximum. Any production rear end allowed.
Safety cages required on any 7.5" or smaller rear end.
No cambered rear ends allowed.
Toyota 602 gear.

Rear Suspension:
May be fabricated. Coil overs allowed. Steel only.

Steering:
Original for type of snout. No exception. Tube upper A frames allowed. Lower A frame stock but may have heim joint welded on.May use factory lower[portcity /howe] lower insted of stock for clip must remaine near stock length. must be quality racing lower arm. no home made junk holding lower ball joint.

Body and Engine:
Can be different manufacturers.

Roll Cage:
Pipe must be at least 1 ¾" O.D(outside diameter).
Full cage bracing mandatory.
All bars that may injure drivers will be padded.
Four uprights joined together at the top minimum of four horizontal bars are required in the driver's door. Three on the passenger side.
A plate of 16 gauge steel approximate size 40" x 20" mounted on driver's side between door skin and roll cage.
Uni-bodied cars:
May be pieced together in the middle. Both sides shall be the same length.

Radiator:
Any radiator. Must be located in the front.

Transmission:
Production model. Must have 2" x 2" hole in bell housing for inspection.

Clutch:
After market allowed.

Flywheel:
After market allowed.

Sway Bar:
Any bar. Maximum 1" diameter.

Seat:
Aluminum racing seat. Left & Right side head support mandatory.

Fuel Cell:
Minimum 8" ground clearance.

Anything not covered by these rules shall remain stock, unaltered, as made by the manufacturer. For the purpose of rule enforcement, the term "stock" shall be understood to mean the parts must be of original equipment manufacture production (ie: GM, Ford, Chrysler).

At the discretion of Unity Raceway Management weight may be added or subtracted to ensure fairness of competition.