THOMPSON INT'L SPEEDWAY

2004

SUNOCO MODIFIED RULES

GENERAL:

ALL 2004 NASCAR RULES FOR THE MODIFIED DIVISION WILL BE ENFORCED FOR THE THOMPSON SUNOCO MODIFIEDS WITH THE FOLLOWING CHANGES AND/OR ADDITIONS.

NO CARBON FIBER OR TITANIUM ENGINE, POWER TRAIN, BODY OR CHASSIS PARTS!

CAR WEIGHT: MINIMUM WEIGHT AT ALL TIMES WITH DRIVER WILL BE 2600 LBS.  MAXIMUM LEFT SIDE PERCENTAGE IS 56.0%. MOPARS WITH ENGINES OVER 359 CUBIC INCH DISPLACEMENT MUST ADD 6.8 POUNDS PER CUBIC INCH OVER 359. PROPER BORE & STROKE FOR ENGINE BEING USED MUST BE MAINTAINED.

AN ALLOWANCE OF ONE HALF OF ONE PERCENT (.5%) OF MINIMUM TOTAL WEIGHT WILL BE ALLOWED FOR LOSS IN WEIGHT DUE TO RACE WEAR. NOTHING MAY BE ADDED OR TAKEN FROM THE CAR TO MAKE MINIMUM WEIGHT/PERCENTAGE.

BALLAST WEIGHT: ALL BALLAST WEIGHT MUST BE BOLTED TO THE FRAME RAILS. NO BALLAST WEIGHT IN DRIVERS COMPARTMENT.

ENGINE:

GENERAL: MUST BE STOCK OEM V8 PRODUCTION CAST IRON BLOCKS AND CYLINDER HEADS. THE BLOCK MUST RETAIN ALL OEM SPECS WITH THE EXCEPTION OF CYLINDER OVERBORE AND SURFACING OF THE BLOCK. ANGLE CUTTING OF THE BLOCK DECK WILL NOT BE PERMITTED. ORIGINAL BORE & STROKE MUST BE MAINTAINED. AFTERMARKET OEM TYPE MAGNETIC STEEL MAIN BEARING CAPS ALLOWED. MUST BE STOCK APPEARING. NO SPLADE CAPS ALLOWED. THE ONLY APPROVED ENGINES ARE; CHEVROLET 350, FORD 351, AND MOPAR 360.  MAXIMUM OVERBORE FOR GM AND FORD IS .045”. MAXIMUM OVERBORE FOR MOPAR IS .030”. NO DEBURRING, GRINDING, CHEMICAL (ACID MILLING) OR ABRASIVE CLEANING OF ANY ENGINE PARTS. NO COATING (EX. TEFLON), PLATING (EX. CHROMING), OR PAINTING OF ANY INTERNAL ENGINE PARTS. OIL RETURN HOLES MAY BE DEBURRED AND/OR COVERED WITH SCREENS. EPOXYING MAGNETS TO THE OIL RETURN AREA IS ALLOWED. NO CARBON FIBER OR TITANIUM ENGINE PARTS.

COMPRESSION: MAXIMUM COMPRESSION IS 11.5:1, CHECKED WITH THE “WHISTLER”. NO TOLERANCE ALLOWED ON MAXIMUM COMPRESSION! THE 2 MOST FORWARD BOLTS ON BOTH SIDES OF THE INTAKE MUST BE DRILLED TO ACCEPT A SEAL.    

CRANKSHAFT: ONLY STOCK PRODUCTION OEM CRANKSHAFTS ALLOWED. CHEVROLET MUST USE LARGE JOURNAL CRANK. REGRINDING OF THE ROD AND MAIN JOURNALS TO A MAXIMUM OF .030” UNDER STANDARD SIZE ALLOWED. THE MAXIMUM ALLOWABLE STROKE TOLERANCE FOR GM AND FORD IS +/- .015”. MAXIMUM STROKE ON A GM WILL BE 3.495”. MOPAR WILL HAVE A MAXIMUM STROKE TOLERANCE OF +/- .005”.   THE ROD JOURNALS MAY BE DRILLED TO OBTAIN THE MINIMUM CRANKSHAFT WEIGHT. NO MACHINING, POLISHING, GRINDING OR ANY OTHER MODIFICATIONS TO ANY PART OF THE CRANKSHAFT ALLOWED. CRANKSHAFT MUST REMAIN AS MANUFACTURED. ONLY NORMAL OEM TYPE ENGINE BALANCING WILL BE ALLOWED. MINIMUM CRANKSHAFT WEIGHT FOR GM IS 50 LBS. MOPAR AND FORD MINIMUM CRANKSHAFT WEIGHT IS 54 LBS. FLUID HARMONIC DAMPERS ARE ALLOWED.

OIL PAN:  ONLY OEM TYPE IN THE PAN OIL PUMPS ALLOWED. NO DRY SUMPS, EXTERNAL OIL PUMPS, TANKS OR ACCU-SUMP SYSTEMS ALLOWED. WINDAGE TRAYS ALLOWED. OIL COOLERS ALLOWED. NO PUMPS OF ANY TYPE MAY BE USED IN THE EVACUATION SYSTEM.

OIL COOLERS: MUST BE INSIDE OF BODY & LOCATED IN FRONT OF ENGINE FIREWALL.

PISTONS & RODS: FLAT TOP 3-RING ALUMINUM PISTONS ONLY. ALL 3 RINGS MUST BE OF MAGNETIC STEEL. VALVE RELIEFS MAY BE CUT INTO PISTONS. NO PORTION OF THE PISTON MAY PROTRUDE ABOVE THE TOP OF THE BLOCK. STOCK TYPE STEEL RODS ONLY. ALL AFTERMARKET RODS MUST BE SOLID BEAM TYPE “SPORTSMAN” ROD WITH A STEEL PIN. AFTERMARKET BOLTS ALLOWED. NORMAL OEM TYPE ENGINE BALANCING ONLY. NO BILLET RODS. MINIMUM ROD LENGTH 5.700”,  MAXIMUM ROD LENGTH 6.250”. ALL RODS MUST BE THE SAME LENGTH. MINIMUM WEIGHT FOR PISTON, PIN, RINGS, BEARING & ROD ASSEMBLY IS 1075 GRAMS.

CAMSHAFT: STOCK LIFTER DIAMETER MUST BE MAINTAINED. NO ROLLER, MUSHROOM, OVERSIZE, CONVEX, CONCAVE OR CERAMIC LIFTERS. ONLY FLAT BOTTOM MAGNETIC STEEL STRAIGHT BARREL LIFTERS OF THE SAME DIAMETER AND LENGTH AS STOCK. MAXIMUM LIFT AT THE VALVE WITH ZERO (0) LASH WILL BE 550”.

TIMING CHAIN: ANY TYPE CHAIN ALLOWED. NO GEAR OR BELT DRIVES.

CYLINDER HEADS: STOCK OEM CAST IRON HEADS ONLY. NO PORT MATCHING OR FLOW WORK. NO GRINDING, POLISHING, BEADING OR CHEMICAL (ACID) MILLING ALLOWED. NO WELDING OR SECTIONING. NO INTERNAL MODIFICATIONS OF ANY KIND INCLUDING PAINTING OR TEFLON COATINGS.  CHEVROLET MUST USE THE “492” CASTING OR THE “OLD STYLE 461 OR 462 TYPE HEADS”, WITH A MAXIMUM 2.02” INTAKE VALVE AND A MAXIMUM 1.60” EXHAUST VALVE.  NO ANGLE PLUG, BOWTIE OR VORTEC HEADS ALLOWED. FORD CLEVELAND OR WINDSOR MUST USE HEADS OF A TWO BARREL DESIGN THAT CAME ON A PASSENGER VEHICLE WITH A MAXIMUM 2.05” INTAKE VALVE AND A MAXIMUM 1.66” EXHAUST VALVE. FORD WINDSOR MAY USE THE CAST IRON “WORLD PRODUCTS WINDSOR JR” CYLINDER HEAD. BARE CASTING PART# 05303B WITH 1.94” INTAKE VALVE AND 1.60” EXHAUST VALVE. THIS IS THE ONLY APPROVED AFTERMARKET CYLINDER HEAD! MOPAR MUST USE PART# P5249574 WITH CASTING NUMBERS 3418915, 4772576 OR 448308 WITH A MAXIMUM 2.02” INTAKE VALVE AND A MAXIMUM 1.60” EXHAUST VALVE. NO W2 OR TA HEADS ALLOWED. THE ONLY MODIFICATIONS ALLOWED ARE THE MILLING OF GASKET SURFACES, THE ADDITION OF SCREW IN STUDS, GUIDE PLATES AND VALVE SPRING SEATS. OPTIONAL VALVE SEALS, POLY-LOCKS OR JAM-NUT DEVISES ARE PERMITTED. MACHINING OF THE VALVE GUIDE BOSS FOR SEALS ONLY. COOLANT LINES WILL BE ALLOWED ON THE ENDS OF THE CYLINDER HEADS ONLY. NO MORE THAN TWO INTAKE MOUNTING HOLES MAY HAVE HELI-COILS. INTAKE AND EXHAUST MOUNTING HOLES MAY NOT BE ADDED OR RELOCATED. HOLES MUST TAKE STANDARD INTAKE MANIFOLD BOLTS.

VALVES: MUST BE IDENTICAL IN APPEARANCE AND CONSTRUCTION AS AN OEM TYPE VALVE. NO AIR DIRECTIONAL DEVICES ALLOWED ON ANY OF THE VALVE SURFACES. VALVE STEMS MUST HAVE A MINIMUM DIAMETER OF 11/32”. STAINLESS STEEL REPLACEMENT VALVES ARE PERMITTED.

VALVE SPRINGS & RETAINERS: ANY TYPE STEEL VALVE SPRINGS ALLOWED. DOUBLE SPRINGS ARE ALLOWED. STEEL VALVE SPRING RETAINERS ONLY.

VALVE JOB: THREE ANGLE VALVE JOBS ALLOWED. WHEN CUTTING THE VALVE SEAT ANGLES, NO STONE OR GRINDING MARKS ARE PERMITTED ABOVE THE BOTTOM OF THE VALVE GUIDE. ALL CUTTING IN REFERENCE TO THE VALVE JOB MUST BE CENTERED OFF THE CENTERLINE OF THE VALVE GUIDE. UPON COMPLETION OF THE VALVE JOB, THE BOWL AREA UNDER THE VALVE SEAT DOWN TO THE BOTTOM OF THE VALVE GUIDE MUST STILL BE THE SAME CONFIGURATION AS FAR AS SHAPE AND FINISH AS IT WAS FROM THE MANUFACTURER. SURFACES AND/OR EDGES WHERE THE CUTTER OR STONE HAS TOUCHED MUST NOT BE POLISHED. HAND GRINDING OR POLISHING WILL NOT BE PERMITTED ON ANY PART OF THE HEAD. UNSHROUDING OF VALVES IS NOT PERMITTED.

ROCKER ARMS: ROLLER ROCKER ARMS ALLOWED. ROCKERS MUST BE INDEPENDENT AND STUD TYPE. NO SHAFT ROCKER SYSTEMS. STUD GIRDLES PERMITTED.  CHRYSLER MAY USE OEM SHAFT SYSTEM.

INTAKE MANIFOLD: STOCK CAST IRON PASSENGER CAR MANIFOLDS OF 2-BARREL DESIGN ONLY.  MANIFOLD MUST BE ONE THAT WAS USED WITH AN OEM TWO BARREL CARBURETOR.  NO THROTTLE BODY MANIFOLDS ALLOWED.  MANIFOLD MUST REMAIN UNALTERED AND AS MANUFACTURED.  NO PORTING, POLISHING, CHEMICAL (ACID) MILLING, DEBURRING, DE-FLASHING, ABRASIVE CLEANING, INTERNAL PAINTING, WELDING, DRILLING OR ENLARGING HOLES.  ABSOLUTELY NO MODIFICATIONS OF ANY KIND.  NO COOLANT LINES IN THE INTAKE MANIFOLD.  A TRACK SUPPLIED INTAKE MANIFOLD AND STOCK GASKETS MUST FIT YOUR ENGINE.  BOLT HOLES MUST BE IN ALIGNMENT AND SAME SIZE AS STOCK.

CARB SPACER:  ONE SOLID MATERIAL SPACER, MAXIMUM HEIGHT OF 1” PERMITTED. SPACER CANNOT BE LARGER THAN BASE OF THE CARBURETOR.  NO WEDGE SHAPE SPACERS ALLOWED.  BOTH THE TOP AND BOTTOM SURFACES MUST BE PARALLEL.  PORTHOLE(S) MUST BE VERTICAL TO THE TOP AND BOTTOM.  NO BEVELING, TAPERING, FLARING OR RADISUING OF PORTHOLE(S) ALLOWED.  ONLY ONE .075” MAX GASKET PER SIDE OF SPACER ALLOWED.

CARBURETOR: THE HOLLEY R4412 IS THE ONLY CARBURETOR ALLOWED. ALL CARBURETORS MUST PASS TRACK SUPPLIED GAUGES. THE ONLY CHANGES THAT WILL BE ALLOWED ARE AS FOLLOWS; THE CHOKE PLATE AND SHAFT MAY BE REMOVED, JETS, POWER VALVE, ACCELERATOR PUMP CAM AND ACCELERATOR PUMP DISCHARGE NOZZLES MAY BE CHANGED. IDLE HOLES MAY BE DRILLED IN THE THROTTLE PLATES. THROTTLE PLATE SCREWS MAY BE TRIMMED FLUSH WITH THE SHAFT. NO OTHER CHANGES ALLOWED. NO RESHAPING, POLISHING, GRINDING, MACHINING OR DRILLING ALLOWED. NO ADJUSTABLE (JETTED) AIR BLEEDS OR CIRCUITS. GASKETS MUST REMAIN UNALTERED.

AIR CLEANER/FILTER: ONLY ROUND MAXIMUM 5” IN HEIGHT DRY PAPER AIR FILTER ELEMENT WITH A MINIMUM 12”, MAXIMUM 14” DIAMETER WILL BE PERMITTED. ALL AIR ENTERING CARBURETOR MUST PASS THRU FILTER. TOP AND BOTTOM OF AIR CLEANER MUST BE METAL AND OF SAME DIAMETER. A MAXIMUM 1” LIP PERMITTED FROM AIR FILTER ELEMENT TO EDGE OF AIR CLEANER. A SHIELD MAY BE USED IN FRONT OF AIR FILTER ELEMENT UP TO A MAXIMUM OF ONE-HALF OF THE AIR FILTER ELEMENT CIRCUMFERENCE AND NOT WIDER THAN THE HEIGHT OF THE ELEMENT. NO AIR INDUCTION DUCTS, BAFFLES, TUBES FUNNELS OR ANYTHING ELSE WHICH MAY CONTROL THE AIR LEADING TO, INSIDE OF, OR BETWEEN THE AIR FILTER AND CARBURETOR. THE AIR FILTER BASE MUST HAVE A MINIMUM ROUND OPENING OF 5”. A 1” MAXIMUM HEIGHT SPACER MAY BE USED BETWEEN THE CARBURETOR AND THE AIR CLEANER. NO PORTION OF THE HOOD MAY BE HIGHER THAN THE BOTTOM OF THE AIR CLEANER. NO PLASTIC AIR CLEANERS OR PARTS.

EXHAUST SYSTEM: HEADERS MUST BOLT DIRECTLY TO THE CYLINDER HEAD-NO SPACERS. NO 180 DEGREE HEADERS. NO “TRI-Y” TYPE HEADERS. EXHAUST PIPES MUST COME OUT OF ENGINE AT THE COWL AND MUST EXTEND A MINIMUM OF 6” PAST COWL.  EXHAUST PIPES MAY RUN BENEATH THE CAR, BUT MUST TURN DOWN AND OUT TOWARD THE BOTTOM OF THE FRAME RAILS OR EXIT OUT THROUGH THE DOOR PANEL.  THERMAL WRAP IS NOT PERMITTED ANYWHERE ON THE EXHAUST SYSTEM.

MUFFLERS:  MANDATORY! SEE GENERAL RULES.  

IGNITION: ELECTRONIC DISTRIBUTORS MUST BE GEAR DRIVEN, USE AN EIGHT LOBE CAM WITH MAGNETIC PICK-UP, STOCK TYPE HOUSING, MOUNTED IN STOCK LOCATION. GM, FORD & CHRYSLER MUST USE A COIL IN THE CAP HEI TYPE DISTRIBUTOR WITH A GM OEM TYPE IGNITION MODULE.  NO AFTERMARKET CAPACITIVE “MSD” TYPE SYSTEMS. THE FOLLOWING WILL NOT BE PERMITTED; ADJUSTABLE TIMING CONTROLS, IGNITION DELAY/TIMING RETARD DEVICES, EXTERNAL RPM LIMITERS, ANY ACCESSORIES THAT REGULATE THE POWER SUPPLY. THE FOLLOWING SYSTEMS ARE NOT PERMITTED; COMPUTERIZED, MULTI-COIL, DISTRIBUTORLESS, DUAL FIRING MODULE BOX, CRANK TRIGGERED OR MAGNETO SYSTEMS.

STARTER: STOCK OR AFTERMARKET ALLOWED.

WATERPUMP: ONLY STEEL OR ALUMINUM OEM TYPE MECHANICAL PUMP IN STOCK LOCATION, TURNING THE SAME DIRECTION OF CRANKSHAFT. IMPELLERS MAY BE ALTERED. NO COOLING LINES PERMITTED ANYWHERE IN THE INTAKE MANIFOLD OR IN THE SIDES OF THE HEADS OR BLOCK.

DRIVETRAIN:

BELL HOUSING: ANY NASCAR APPROVED SAFETY BELL HOUSING. MUST BE A FULLY ENCLOSED BELL HOUSING.

CLUTCH & FLYWHEEL: OEM OR EXACT REPLACEMENT MAY BE USED PER THE FOLLOWING; MINIMUM SIZE CLUTCH AND PLATE IS 10”. NO ALUMINUM, TITANIUM OR CARBON FIBER CLUTCH OR FLYWHEEL PARTS INCLUDING FASTENERS. NO DRILLING, LIGHTENING OR ANY MODIFICATIONS. MINIMUM WEIGHTS ARE; FLYWHEEL 12.5 LBS., CLUTCH COVER 13.0 LBS., CLUTCH DISC 3 LBS.

TRANSMISSION: STOCK OEM 3 OR 4 SPEED MANUAL TRANSMISSION WITH CAST IRON, ALUMINUM OR MAGNESIUM HOUSINGS PERMITTED. NO TOP LOADERS, SPECIAL PRODUCTION, OVERDRIVES, 5 SPEEDS OR AUTOMATICS ALLOWED.  ALL INTERNAL PARTS INCLUDING BEARINGS, MUST BE STOCK OEM OR EXACT REPLACEMENT ONLY.. ANGLE CUT FORWARD GEARS ONLY. NO SQUARE CUT FORWARD GEARS. STOCK OEM GEAR RATIOS ONLY.  NO WELDING, MACHINING, DRILLING OR LIGHTENING OF ANY PARTS. HIGH RATIO MUST BE 1:1. NO OTHER GEARS MAY HAVE A RATIO CLOSER THAN 1.2:1. 1^ST GEAR MAY BE REMOVED FROM 4 SPEED ONLY. TAIL SHAFT MAY USE ROLLER/NEEDLE BEARINGS. ALL GEARS MUST BE IN WORKING ORDER FROM INSIDE THE DRIVERS COMPARTMENT WITH MECHANICAL LINKAGE.

REAR AXLE: REAR AXLE ASSEMBLY MUST MEET THE FOLLOWING REQUIREMENTS; ONLY ALUMINUM OR STEEL QUICK CHANGE AND NON-QUICK CHANGE CENTER SECTIONS EQUIPPED WITH ALUMINUM OR STEEL SIDE BELLS PERMITTED. FULL FLOATING MAGNETIC STEEL REAR AXLES ARE MANDATORY. ONLY LOCKED REAR DRIVE AXLE ASSEMBLIES PERMITTED. NO LIMITED SLIP OR RATCHET TYPE DIFFERENTIALS. FOR THE PURPOSE OF CHECKING A PRE-DETERMINED FINAL DRIVE GEAR RATIO, WHEN JACKED UP BOTH REAR WHEELS MUST ROTATE IN THE SAME DIRECTION WITH EACH TRAVELING THE SAME ROTATIONAL DISTANCE.

GEAR RULE: MINIMUM 4.56:1 – MAXIMUM 5.04:1 FOR QUICK CHANGE. MINIMUM 4.56:1 – MAXIMUM 4.86:1 FOR STRAIGHT REARS.

TIRES: AMERICAN RACER 13.5 SLICK. RIGHT SIDE TIRE IS 132 COMPOUND, 26.0 X 13.5 X 15. LEFT SIDE TIRE IS 131 COMPOUND, 25.5 X 13.5 X 15. LEFT FRONT TIRE IS 131 COMPOUND, 25.0 X 13.5 X 15.

TREADWIDTH: MINIMUM TREADWITH 81 ½”, MAXIMUM 83” BOTH FRONT & REAR. (SEE GENERAL RULES)

COIL OVER SHOCK ASSEMBLIES: ALL SHOCKS ARE SUBJECT TO TRACK APPROVAL. NO DOUBLE ADJUSTABLE SHOCKS, SHOCKS WITH EXTERNAL RESERVOIRS OR REMOTE/ELECTRICALLY CONTROLLED SHOCKS ALLOWED. SPRINGS MUST BE MAGNETIC STEEL. ASSEMBLIES CONSIST OF: SHOCK, ENDS AND COLLARS, LESS SPRING. RACERS NET PRICE MAY NOT EXCEED $275.00 PER ASSEMBLY. ANY APPROVED SHOCK ASSEMBLY MUST BE AVAILABLE TO ALL COMPETITORS. THE BURDEN OF PROOF IS ON YOU AT ANY EVENT. ACCEPTABLE PROOF WILL BE ANY RECENTLY (UP TO DATE) PUBLISHED CATALOG WITH YOUR SHOCK ASSEMBLIES PART NUMBER AND PRICES. NO COPIES, OR COMPUTER REPRODUCTIONS OF CATALOGS OR FLYERS!

SPINDLES, WHEEL BEARINGS AND HUBS: FRONT SPINDLES MUST BE ATTACHED TO THE FRAME USING STEEL CABLES. SEE NASCAR RULE.

BRAKE ROTORS:  DRILLED OR SCALLOPED ROTORS ARE  NOT ALLOWED.

ADJUSTING DEVICES: THE ONLY ADJUSTING DEVICE IN THE DRIVERS COMPARTMENT WILL BE FOR BRAKE PROPORTIONING. NO OTHER DEVICES OF ANY KIND TO CONTROL OR ALTER THE HANDLING, WEIGHT PERCENTAGE, RIDE HEIGHT AND ETC. OF THE CAR.

ADDITIONAL INFORMATION:

SUNOCO MODIFIEDS MUST ALSO COMPLY WITH THOMPSON INTERNATIONAL SPEEDWAY GENERAL/SAFETY RULES.

THOMPSON INTERNATIONAL SPEEDWAY RESERVES THE RIGHT TO CONFISCATE FROM THE RACE WINNER ANY OR ALL OF THE FOLLOWING ITEMS; INTAKE MANIFOLD, IGNITION MODULE, DISTRIBUTOR, TACHOMETER, ETC. THE COMPETITOR WILL RECEIVE EITHER NEW PARTS OR MONETARY COMPENSATION FOR ANY AND ALL CONFISCATED PARTS.

Sources:  Russ Dowd/Thompson International Speedway PR
Posted:  November 27, 2003