Pro Stock 4-Cylinder
NORTHERN MICHIGAN SPEEDWAY
NOTE: RACECEIVERS MANDATORY! All drivers will be required to operate a raceceiver during all hotlap sessions, qualifying and race events. These devices will be used for on-track safety notice, disciplinary action and line-up procedures.
Raceceiver is to be tuned to 454.0000.
Any driver who does not have a Raceceiver on, or operational, will be instructed to leave the track. NO EXCEPTIONS!
Radios and mirrors ARE NOT permitted.
There will be NO WARNINGS given out for bad behavior such as; No throwing a fit on the racetrack or pit area NO jumping on the track officials, NMSW officials, scorers, flagman or track owner. No going to another pit to argue this includes driver, crew and anyone. You WILL NOT exit your car on the track.
1) Chassis: No station wagons or convertibles. Extended cabs allowed. Weight may be added but must be securely fastened (officials discretion).
2) Body: Complete steel or aluminum body must remain intact. Any exterior metal work must be done in steel. Interior metal work may be done in aluminum. Frame rails can be reinforced as needed. Sub frames can be connected. Aluminum or sheet metal is allowed from end of cab, back. Maximum height of rear spoiler (off deck) - 8 inches, clear material, at rear. Drive shaft must have loop. Rear end stock for that make/model/year but may be locked. All glass must be removed. Windshield mandatory - Lexan recommended. Drivers seat must be securely fastened & seat adjustment track pinned or bolted to prevent movement. Driver entry/exit 13x24 inches unrestricted. Window net mandatory. No reinforcing of front bumper allowed. Bumper must be stock and in stock location. Bumper must be curved in so it won’t cut tires. Small radiator guard behind grill allowed. Both sides of body must be straight in line. No holes allowed in back of car or in tailgate of truck. Sheet metal must be run down to the bumper. Ride height minimum of 6”.
3) Rear End: No cutting or welding on housing. No aftermarket A-frames allowed. No air shocks or adjustable of any kind. No adjustable links on rear end.
4) Engine: Must be in stock position. Must be GM or Ford. No D-stroke engines. Clean up bore of 30 thousandths max. Stock pistons only. Porting and polishing of head is allowed. Milling of head is also allowed. Engine must be in front of driver. Radiator overflow catch (can) mandatory. One 2-bbl carburetor only. Headers are allowed. No aftermarket ignition systems. Engine - #1 cylinder - must line up with ball joint. No aluminum heads on Ford Rangers and Mustangs.
5) Tires & Wheels: No recaps. Aluminum wheels allowed with safety studs. Steel wheels are allowed with one inch safety nuts. American Racer P60-215-13 tires. 8” maximum rims.
6) Roll Cages: Must have four upright posts boxed together at hump of frame. There must be three bars in drivers door as close to door as possible for your protection. Door plate & foot plate mandatory - 10”x30”x1/8”. Must have bracing from side to side, front to back to provide more safety. 1 ½ “ O.D. with 125 thousandths thickness is the smallest pipe you may use. Tubing is to be no smaller than 1 ½” O.D. with .090 thousandths thickness. All welds must be inspected. Must be of good quality pipe. No exhaust pipe in cage. For trucks, roll cage must be boxed together at hump of frame over the rear wheels to keep cage from tipping back.
7) Seat Belts: Aftermarket 5-poing seat belt mandatory - must be secured to roll cage.
8) Scatter Shield: Mandatory over bell housing.
9) Clutch: Racing clutch allowed. Steel flywheel single disc, not multiple disc.
10) Intake: Fuel injection manifolds allowed. OFFY C type manifolds allowed.
11) Carburetor: 1 11/16” #4412 Holley 2-bbl. 350-cfm or 500-cfm allowed.
12) Firewall: Stock
13) Electric Fuel Pump: Must have a mercury switch on it so when motor stops the fuel pump will stop.
14) Sissy Bars: 1 ¼” sissy bars tight to vehicle allowed.
15) Flywheels: Cast iron only - no cutting allowed.
16) Bell Housing: 1” hole cut in bell housing to check flywheel.
17) Shocks: Rubber bushing in shocks - no racing shocks allowed.
18) Brake torsion valves: Allowed.
19) Helmet: Must be 85 snell or better.
20) Racing suit: Mandatory.
21) Fire Extinguisher: Mandatory - must be mounted in a quick release bracket within drivers reach.
22) Weight: 2000 Engine - vehicle must weigh 2300 lbs
2300 Engine - vehicle must weigh 2300 lbs
2.5 Engine - vehicle must weigh 2500 lbs
Double overhead cam - vehicle must weigh 2500 lbs
23) NO SCREW JACKS OF ANY KIND ALLOWED. NO COIL OVERS.
24) Mufflers are mandatory.
25) 4 Cylinder Modifieds converting over to Pro Stock 4 Cylinder:
Must have a complete full body
Maximum left side weight 54%
Maximum rear weight 48%
May separate coil overs and use same shock and spring
All adjustable links on rear end must be welded
Track official may add weight to 4 Cyl Mods converted over to this class
To be eligiable to run midseason and Championship night you must race any two week prior.