***** ATTENTION ALL FOUR CYLINDER DRIVERS *****carolina
***** ATTENTION FOUR CYLINDER DRIVERS *****
After careful consideration, Carolina Speedway has made the decision to switch from SECA/MMSA Four Cylinder rules to follow Pro Stock 4 Rules. Our rule book has been updated and is up to date with these changes. These changes are effective IMMEDIATELY.
All four cylinder points will be reset to zero and we will start the points for Pro Stock 4 on Thursday April 18, 2019.
Rules are also listed below to make them easy to find:
2019 PRO STOCK FOUR RULES
Very limited modifications are allowed to the cars, suspensions and engines. The class is open to
most 4-cylinder, rear wheel drive automobiles, 2-wheel drive mini-pickup trucks and station
Body may be fabricated from steel or aluminum, but must follow stock body lines. Cannot exceed stock body dimensions. No holes in hood. 2 ½ in high hood scoop is allowed. Must be closed in front and sides, but can be open in back. Complete air breather must be covered.
6 in. spoilers are allowed and cannot be any wider than the upper edge of the quarter panel. Body must sit on frame in OEM position. Front firewall must be steel and must be in stock location. Floor pan must be stock OEM in stock location. Any patch panels installed in floor pan due to rust or damage must be steel. Rear firewall may start behind driver’s seat. Aluminum or steel may be used to box in driver’s compartment. Cars with a boxed in interior must have a 12” x 12” removable inspection panel to check enclosed area. All interior panels must be sealed well enough to prevent fire, hot oil, or fuel from entering driver compartment. Hoods must be run at all times unless crash damage prevents it. All vehicles must have roll cage as specified in safety section Carolina Speedway General Rules. Must run stock appearing noses. Rear of car must be enclosed down to the back bumper at track officials approval. May run with OR without roof. If running without roof, must run arm restraints.
CHASSIS AND SUSPENSION:
Suspension must be stock for type of vehicle being used. Front and rear suspension mounting
points must be stock. Adjustable castor/camber plates are allowed. Adjustable spring cups are
allowed on front and rear. Upper and lower A-arms must be stock for chassis used. Upper may be modified. Rear trailing arms must be stock and non-adjustable. Uppers may be modified for
pinion angle adjustment. Mono-ball control arm bushings are allowed.
Steering gear must be OEM for make of vehicle being raced. Quickeners allowed. Steering column may be after market collapsible type or OEM with quick release steering wheel hub mandatory.
Non-adjustable lowering blocks allowed on leaf springs. All springs may be changed, but must be
in stock location.
Any steel non-adjustable shock is allowed. Must be in stock position in front and rear.
Must be naturally aspirated, 2 valve per cylinder engines only. No rotary or DOHC engines allowed. No fuel injection or multiple carburetors allowed. Engine must be same make as car. Must be OEM only with maximum overbore of .080. 2500 cc is maximum allowed. 2500 Ford blocks are not allowed.
Must be in Stock OEM location. Solid mounts allowed. Crankshaft and Rods: Must be stock OEM with stock stroke. Rods may be any steel, no titanium. 2500 Ford crankshafts are not allowed.
May be any flat top. 3TC Toyota may use .235 dome. .267 dome must add 50lbs. 20 and 22 may use .125 dome.
Must be stock OEM, absolutely no porting or polishing allowed. No extrude honing allowed. No acid porting allowed. Ports must remain at factory OEM shape and volume. Head may be angle cut. A bowl cut is allowed but, cannot exceed the ID of the valve seat and can be no deeper than the valve guide. Bowl cut must be concentric with the valve guide.
CRANKSHAFT AND RODS:
Crankshaft must be stock OEM with stock stroke. Rods must be any steel, no titanium.
2500 Ford crankshafts are not allowed.
Valve angle must remain OEM stock. May have competition valve job, any seat angle allowed. Valve may be any steel, stock diameter only. Ford 2300 intake valve is max 1.751 and 1.509 for the exhaust valve. No hollow stem valves allowed. Valve springs must be any steel. Double springs are allowed. Retainers may be any steel, no titanium. d .025 lash for solid lifters at the valve. No roller cams or rockers allowed. Adjustable cam gears are all
May be .425 maximum lift. Lift will be measured with 0 lash for hydraulic lifters and .025 lash for
solid lifters at the valve. No roller cams or rockers allowed. Adjustable cam gears are allowed.
OIL PAN AND PICKUP:
May be any wet sump, steel only.
Water pumps are to be stock type bolted, and in original place. Belt driven only. Aluminum racing radiator may be used.
May use any factory cast iron or tubular exhaust manifold or any aftermarket 4 into 1 header. No
merge collectors or Tri-Y headers allowed.
Any type allowed.
OEM stock only. No porting modifications whatsoever. No internal coatings on ports in head or intake allowed.
Must be stock type distributor and coil. May use Mel’s ignition. No aftermarket multiple spark or
adjustable electronic type systems allowed. No traction control.
Stock OEM or Holley 350 # 7448. No modifications to the outside of carburetor or venturas allowed. May drill air bleeds on stock carburetor. Holley must remain stock appearing. May change jets, etc. for tuning. A 1in carburetor spacer is allowed with only one gasket per side.
Any allowed, but electric must have a kill switch that will cut off the pump if the oil pressure drops.
Rear end must be stock type non-floater up to 8.8 in. May change gear, must be locked. No wheel spin sensing differentials allowed. Driveshaft must be steel and be painted white.
Transmission must be OEM stock with all gears intact and operable. Fly wheel must be stock and weigh a minimum of 16 lbs. Clutch and pressure plate must be stock type, single disc with solid lining. Must have a minimum thickness of 3/16 in steel scatter plate around bell housing to contain clutch or flywheel in case of failure.
Must be OEM stock for type of vehicle used. Rear disc ok but must use OEMstock rotors and calipers. Rotors cannot be cut down or lightened. Any racing pedals may be used. No cockpit adjustable brake bias bars allowed. All four brakes must be in working order, but you may run a right front shutoff. This means all parts must be in place. Track officials have the right to confirm that all 4 brakes are operating.
Any steel 7in Maximum width, 13in diameter. Bead lock may be used on right side only.
Any 60 or 70 Series Street legal tire or approved Towel City recap, hard compound. Tires cannot be siped. No tire softening agents of any kind are allowed. Tires cannot be screwed to the wheels in any way.
Cars must weigh 1 lb. per cc. All cars must have cc’s posted on hood in a minimum of 3 in. numbers, MANDATORY. 2500cc maximum. 2,000 lb minimum weight after race with driver.
Pump gas or approved race gas may be used. No performance additives of any kind allowed.
Fuel cell must be in compliance with safety section of Carolina Speedway track rules.
* Note: Roll cage, seat and belt specifications and all other safety rules will be posted in the general track rules section.
ANY ITEM NOT SPECIFIED ABOVE MUST BE APPROVED BY THE TECHNICAL DIRECTOR
BEFORE COMPETITION OR IT IS NOT LEGAL!
1. $300.00 FEE FOR THE TOP END OF THE ENGINE AND AREAS OF THE CAR. $100.00 WILL BE
RETAINED FOR TRACK FEE.
2. AN ADDITIONAL $600.00 FEE FOR TECH OF THE LOWER END OF 4 CYLINDER ENGINES,
TO WEIGH OR CHECK THE CRANKSHAFT. $100.00 WILL BE RETAINED FOR TRACK FEE.