2020 Unified Dirt Street Stock Rules
ALL GENERAL TRACK RULES APPLY. PLEASE REFER TO GENERAL TRACK RULES SECTION FOR CAR NUMBER REQUIREMENTS, APPEARANCE GUIDELINES, START TIMES, AGE REQUIREMENTS.
RACE TEAMS NOT COMPLYING WITH GENERAL RULES WILL NOT BE ALLOWED TO COMPETE. RULE VIOLATIONS ARE LISTED IN THE GENERAL RULES.
IF IT DOES NOT SAY IT IS ALLOWED IN THE RULES, IT IS ILLEGAL. IF YOU ARE UNSURE OF ITS LEGALITY PLEASE CONTACT A TRACK OFFICIAL. Taking Advantage of “LOOP HOLES “IN THESE RULES WILL NOT BE TOLERATED. ALL RACE CARS WILL BE SUBJECT TO INSPECTION BY TRACK OFFICIALS AT ANYTIME.
Rules apply at all times car is on track. Snell-rated SA2010 or SA2015 helmet required. Roll bar padding required in driver’s compartment. Recommended: Fire retardant padding. SFI-approved full fire suit required. Fire retardant gloves, shoes and neck brace (or head and neck restraint) required. Right and left seat head supports required if using head and neck restraint system. Recommended: Fire retardant head sock and underwear, collapsible steering shaft. Driver-side window net required, minimum 16 inch by 20 inch ribbon or mesh style, and must be mounted to roll cage so latch is at top front of window. Minimum three inch (two inch with head restraint system) wide SFI approved five point safety belt assembly required, must be mounted securely to main roll cage. Recommended: Safety belts no more than two years old. Kill switch required within easy reach of driver and must be clearly marked ‘OFF’ and ‘ON’.
1964 or newer U.S. manufactured rear wheel drive passenger cars full frame or unibody. Minimum 107.5-inch wheelbase for 108-inch car, 111.5 for 112-inch wheelbase car and 115.5 for 116-inch wheelbase car, maximum one-inch difference from side to side. Camaro, Firebirds, El Camino’s, convertible’s, and station wagons are prohibited. Other models are approved provided they are the same body configuration, meet the spirit and intent of competitive racing, and must be approved by Track Officials. All frames or unibody’s must remain stock unaltered. X-Bracing, plating for strength or repair is allowed. The front and rear frame sections of unibody race cars will be connected by a minimum of 2”x 3”x 0.12” square tubing, safely welded to maintain a solid floor structure. Unibody floors must remain intact. No under slung frame rails allowed. Rear frame replacement is allowed for rusted rear frame rails. Minimum of 2”x 3” rectangular tubing must be used in place of rear frame rails, placed no further back than the rear spring pockets and no longer than factory specs.
WEIGHT AND BALLAST:
Added weight (ballast) may be steel or lead. All weights must be securely attached for inspection. Loose weights are prohibited. Added weights must be painted white and have car number on each piece. Weight must be secured by no less than two ½” diameter bolts. The maximum spacing between bolts is 10”. No more than 50 pounds of weight for every two bolts. No weights may be added outside the body or inside driver’s compartment. Weights added behind the rear end shall be no lower than the bottom of the frame member to which the weight is attached. No Ballast or Ballast type wheel spacer allowed on rear axle tube. Loss of ballast penalty see track operations rules.
All cars with Automatic Transmission must weigh a minimum 3,100 lbs. All cars with Manual Transmission must weigh a minimum of 3300 lbs. All Weights and measurements are with Driver in Car after Competition.
All cars must maintain a neat appearance. Cars must have stock appearing bodies with O.E.M Steel or O.E.M Steel replacement panels. NO ALUMINUM ALLOWED. Body swaps are allowed as long as body matches wheelbase of the frame or APPROVED BY TRACK OFFCIALS. Must have OEM Roof. A and B pillars must be oem for body your running. Fabricated body components are allowed as long as they have the same steel thickness, wheel openings and contours of the O.E.M. components. Bodies must be stock appearing.
Rear spoilers are allowed rear of trunk only, maximum 5” of material Measured base to tip and must remain straight and no wider than 60 ½” no braces or side panels. No Fins, Lips, Rutter’s or any other Aero Dynamic Devices Allowed.
All body panels may be gutted, including hood, roof, fenders, doors, quarters and trunk.
All cars must have both A Pillars Labeled 3100 or 3300 Identifying what Transmission they are Running.
Hood must be separate from fenders in O.E.M. location, with rear sealed off from drivers compartment with sheet metal or Aluminum.
All inner wheel wells may be removed.
Rear edge of trunk may be trimmed or removed only if aftermarket tail piece is used. Trunk must be closed off from driver’s compartment. All holes covered by rust or equipment removal must be covered by steel.
Stock dashboard must be removed and replaced with Steel or Aluminum. Passenger side center line to door Not to Exceed past Dash Cross Bar, only 1 Dash bar allowed.
Minimum of 3 Window Bars in front of Driver, Windshield Screen Recommended.
All glass (windows, headlights, etc.), exterior body moldings (chrome trim, door handles, etc.) and combustible materials (interior, seats, headliners, etc.) must be removed. Opera windows may be closed off by steel, or lexan. •All factory trunk and hood latches must be removed and replaced with Clip style hood pin assembly. Minimum 4 hood, and 2 trunk pins required.
Front and rear bumpers must mount in stock location. Minimum 8” ground clearance on nose of car. Cars using a plastic nose or tail piece may use 1 3/4” round tubing securely fastened to the frame and no wider than the factory bumper. Any exposed bumpers must be strapped.
Rub Rails are allowed and can be no larger than 1” in diameter and have maximum wall thickness of .125”and have the ends cut at a 45-degree angle and be capped and be flush mounted to the body. The rub rail must be mounted between the center of the wheel and top of the rim and be no longer than 4” from each wheel opening.
NO HOOD SCOOPS! or Hood Openings
Rocker panels material may be steel, plastic or aluminum Maximum 6” in height and must be OEM appearing and cannot
be lower than 5” from ground.
•Firewall may be replaced using min 18-gauge steel. Firewall may not be located any further back than rear of oval body mount frame hole.
Floor must remain intact, if your floor is badly rusted or has been removed, you must patch or replace it in a factory appearing manner with 20 gauge (.0359”) steel. Right side of floor may be no higher than 4” from the top of the stock right side frame rail and equal to transmission tunnel. (Drive shaft tunnel does not mean transmission bell housing). With the exception of UNIBODY Cars must run Stock Floors.
Rear firewall maybe located no further forward than rear halo supports, and no higher than bottom of rear opera window
and must be Flush with Trunk Sill.
Tow Hooks Front and rear tow hooks capable of supporting the weight of the car are mandatory and accessible to wrecker personnel.
Mirrors are prohibited.
WHEELS AND TIRES
•Aftermarket steel 15-inch X 8-inch racing wheels only. Minimum weight of 19lbs. Bead locks allowed on Right Rear only
. A minimum of 5/8-inch wheel studs and 1-inch steel lug nuts are mandatory. Wheel spacers allowed up to one inch thick. Foam style or soft plastic mud plug allowed on right rear only and Must be Bolted.
Tires must be a Goodyear Eagle Short Track Special D3264-C400, D2599, D2342, D2345, D3268, 27 inch or 27.5 X 8-inch X 15 inch, Hoosier 26.5-inch X 8 X 15-500- and 27-inch X 8-inch X 15 inch-500. Tire reconditioning is allowed with a 16 grit or finer fiber disk with approval of Track officials. G60 Stamped IMCA tire allowed. Sipping allowed ONLY on the G60 IMCA Stamped tire. No grooving on any tires. COMBINATION OF WHEEL SPACER OR OFFSET WHEEL CANNOT EXCEED 2” OF TOTAL OFFSET PER WHEEL.
All 4 tires must match
Wheel covers must be Bolted and Rings must be welded.
Roll cage must be acceptable to track Officials. ALL NEW CONSTRUCTED ROLL CAGES MUST MEET U.D.T.S.S.R. Diagram. All bends in the roll bar tubing must have a smooth radius and no kinks. It is mandatory that all joints be gusseted. Offset roll cages are prohibited. Laid-back roll cages are prohibited. The roll cage must be a four-post design consisting, in general, of: a vertical main hoop; top hoop or halo bar with diagonal bar; and left and right front post. SEE ROLL CAGE DIAGRAM.
The main hoop must connect to the left and right frame rails, behind the driver, and be diagonally braced.
The main hoop may be located no further back than the rear body mount by the frame kick-up (on metric frames). The back of the main hoop may be located no further back than 82 ½ inches from the center of the front lower ball joint.
NO NEW I.M.C.A. Type Roll Cages will be Acceptable.
Any cars utilizing the I.M.C.A. stock car rule must securely mount 25lbs of ballast in front of firewall for every 1 inch
further back than the 82 ½ inch rule.
Seat location Metric Chassis is MAXIMUM of 80 3/4” from Lower Ball Joint to front side of Seat Measured at shoulder Harness. Metric Chassis 108” MAXIMUM 66 ½” inches from the back of the engine block to the front side of seat, measured at the shoulder harness. For 112” Chassis 82 ¾” 116” Chassis 84 ¾ “ Maximum.
The main hoop must have a horizontal bar at the midpoint. The main hoop bar must be round steel tubing no less than
1 ¾” in diameter and have a minimum wall thickness of 0.095 inches.
All other main hoop support bars may be round steel tubing no less than 1 ¾” in diameter and have a minimum wall
thickness of 0.095 inches.
DOM tubing recommended. Black pipe, exhaust tubing, formed pipe, etc. is prohibited.
The top hoop must attach to the main hoop, and left and right front posts. The top hoop must be diagonally braced. A horizontal “dash” bar must connect the left and right front posts. The top hoop, and left and right front posts must be round steel tubing no less than 1 ¾” in diameter and have a minimum wall thickness of 0.095 inches. The dash bar may be round steel tubing no less than 1 ¾” in diameter and have a minimum wall thickness of 0.095 inches. “A” pillar supports are allowed.
The driver’s side front post must be connected to the main hoop by three, or more, equally spaced, horizontal bars, mounted flush with the outer door skin. The door bars must be connected by two, or more, equally spaced vertical braces and must attach to the main frame by two, or more, equally spaced vertical braces.
A foot protector bar is mandatory.
All driver side door bars and braces must be round steel tubing no less than 1 ¾” in diameter and have a minimum wall thickness of 0.095 inches.
The complete driver’s side door bar area must be plated with steel plates no less than 0.095 inches thick.
The passenger side must be equipped with a minimum of three door bars.
Horizontal bars must be equally spaced and connected by two, or more, equally spaced vertical braces. All passenger
side door bars and braces may be round steel tubing no less than 1 ¾” in diameter and have a minimum wall thickness of
The main hoop must be connected to the back of frame kick up by a minimum of two bars. The bars must be round steel
tubing no less than 1 ¾” in diameter and have a minimum wall thickness of 0.095 inches.
All roll bars exposed to the driver, and left side door bars, must be padded. All steel bars in roll cage area must be a
minimum 1 ¾” diameter.
Chassis’ must be equipped with a fuel cell protector bar. The fuel cell protector bar must stay within the confines of the
trunk, ahead of the rear bumper, and no lower than the bottom of the fuel cell.
All roll cages must provide 2-inches, or more, clearance, measured from the bottom of the top halo bar of the roll cage to the top of the driver’s helmet, when the driver is seated and strapped in, with the helmet on and in the driving position. The main hoop on 108” metric frame is no further back than 82 ½”
112” Chevelle frame 84 ½”
116” Monte Carlo 86 ½”
All components and mounts must be steel, unaltered O.E.M, in O.E.M location and match frame.
•Rubber, polyurethane or nylon lower A-frame bushings only. No offset or bearing type. O.E.M or O.E.M replacement ball joints allowed.
No rebuildable or raised ball joints.
•Upper A-frame may be replaced using aftermarket upper A-frame. ALL “A” Frames used must meet OEM Specifications. No adjustable cross shafts and no slotting allowed. NO Bushing Type, Bearing Type, Heim Joint Type upper control arms allowed! Steel Coleman sportsman hub is approved.
•Sway bars are allowed as long as in stock location and OEM year make and model and NOT hollow, stock brackets and
rubber, or poly urethane bushings.
All components must be steel, unaltered OEM, in OEM location and match frame. Exceptions are: bolt on spindle savers allowed, OEM steering column may be replaced with steel knuckles and steel steering shafts (collapsible recommended). Quick release steering wheel required – steering wheel must be removable, steering quickner allowed. NO Aftermarket or made for racing steering boxes allowed. 2 1\4 Turns Minimum with any box lock to lock at the output shaft at the box Aftermarket 3-piece IMCA stamped spindle part number 91034501-L and 91034501-R is allowed
NO Base valve or Bulb shocks Allowed. Must run steel non- adjustable, unaltered shocks in Stock location! SEE DIAGRAM for location. NO Exceptions Raising or Lowering. ALL SHOCKS must be “STOCK” type shocks! No Gas port, Schrader or Bladder type allowed. Shocks must be able to collapse by hand at any time. No external or Internal bump stops allowed. Rear lower shock mount must remain in OEM Stock location! $50 claim on any one shock. See claim procedures at end of rule book.
•Must run steel springs in stock location only. Racing rear spring mounts can be installed on rear axle housing. Must be mounted in center of rear axle. No Screw type cups allowed Non-adjustable spring shims are allowed, front and rear. NO Spring Rubbers Allowed. Front springs must be a minimum of 9 ½”
•Leaf spring cars are allowed up to a five-inch (5”) spring shackle mounted in stock location and must be equal length side
•All components and mounts must be steel, unaltered O.E.M., in O.E.M. location. OEM Rubber or polyurethane bushings allowed. All trailing arms and mounts must be O.E.M. and in O.E.M. location and mounted with a single ½” diameter round hole maximum. Trailing arms can be boxed for strength or replaced with DCA type aftermarket trailing arms. NO adjustments on any trailing arms! Measurements for rear control arms are as follows 73-77 GM Upper 11.25 inches, Lower 22.375 inches 78-88 GM Upper 11.25 inches, Lower 19.25 inches measured from bolt hole to bolt hole.
•Any extra mounting holes on rear end brackets must be removed, or covered with steel and welded.
•Center of rear lower control arm bolt must be 2.25 to 2.5 inches from bottom of housing and equal from side to side.
•Any O.E.M. steel unaltered non-cambered rear end is allowed. No factory or aftermarket Posi-traction, limited slip or Ratchet style allowed! FULL SPOOL, Mini spool or welded carriers allowed. O.E.M. or steel aftermarket axels allowed. (No gun-drilled axels). FORD 9” Stock rear end or Floater type rear end permitted. Any combination okay as long as parts are steel. No aluminum except drive flanges. No independent rear end (Corvette, Jaguar). One-inch inspection hole in housing required. NO SCALLOPED OR POLISHED (REM) Ring Gears or Components. No torque dividing mini spools or differentials. Ford 9” and stock rear ends may run rear disk brakes with a Maximum rotor thickness of .810 inches & Minimum of .750 No Cambered rear ends allowed.
Axle shafts must be equal diameter on both sides.
•Steel, unaltered O.E.M., or unaltered O.E.M. replacement, operative 4-wheel brakes allowed. All 4 Wheels Must Work
Front components must match frame and maintain minimum O.E.M. dimensions for hubs, rotors, calipers. O.E.M.
diameter caliper pistons only. No vented, scalloped, or ceramic coated rotors.
No floating brakes allowed. No brake shut off devices allowed. No adjustable proportion valves.
Brake lines must be visible. (Not running thru tubing or frame) Plastic brake lines allowed.
You may remove O.E.M. vacuum brake booster and master cylinder and replace with O.E.M. manual brake master
Rear Calipers must be OEM piston size for frame running. Metric frame must run metric calipers.
No aftermarket brake pedals.
O.E.M. unaltered cast iron exhaust manifolds allowed. 1 3/4” Maximum Round tube headers allowed. No over the top headers. No Step Headers Allowed. All primary header tubes must enter directly into one collector at same point at end of header. Collector and exhaust pipe can be Maximum size 3” OD. Must remain dual exhaust, no crossover or ‘’Y’’ pipes. Exhaust must have a turn down and exit behind firewall. (Recommend exhaust exit behind driver.) Mufflers must be installed at tracks discretion
•Gasoline or E85 only. Racing fuel is allowed. No performance enhancing or scented additives allowed. Track officials reserve the right to test any competitor’s fuel at any time. The specific gravity must read from .710 to .780 at 60 degrees Fahrenheit, factored by a specific gravity temperature chart. Track Official has the ability to conduct laboratory analysis of fuels. Samples for lab analysis may be taken from a competitor’s fuel tank at any time at the discretion of the Track Official Technical Inspector. If samples are taken, competitors must identify the specific brand of fuel they are utilizing. Any sample must meet the dielectric constant for the declared brand of fuel being used. FUEL WITH AN OCTANE RATING IN EXCESS OF 110 WILL BE CONSIDERED ILLEGAL. The use of scent masking agents is not permitted and will be considered a fuel violation.
•FUEL SYSTEM Mechanical OEM push rod type fuel pumps only. All cars must be equipped with a racing fuel cell. The maximum capacity of the fuel cell is 22 gallons, and a minimum of 20-gauge steel. Fuel cell must be securely fastened, nonadjustable, in trunk area, behind rear tires, no further forward than the factory seam where rear frame rail can be replaced and must have a metal firewall between driver and fuel cell. Minimum height of bottom of fuel cell must be 12 inches at all times. The container must have (2) 1” by 1/8” steel straps around all 4 sides. Fuel cell vents including cap vent must have check valves. Fuel lines placed through driver’s compartment must run through metal pipe or conduit. One fuel filter only and cannot be placed in driver’s compartment. Fuel cell vent hose must be below fuel cell.
IMCA type fuel flap mandatory.
Street stock engines must run an unaltered Holley Model 4412S, 4412C or 4412CT two-barrel, carburetor. Carburetor Body – No polishing, grinding, or drilling permitted. No billet metering blocks allowed. Metering block must maintain stock appearance. No screw inn style air bleeds or plugs permitted. Any carburetor can be claimed either for $25.00 and a swap of carburetor from claimer’s engine used in that race, or $250.00 outright. The claim must be for like carburetor. Track officials reserve the right to claim or claim swap any carburetor. Please see claim procedures at end of rule book.
Gasoline or E85 only. Racing fuel is allowed. No performance enhancing or scented additives allowed. Track officials reserve the right to test any competitor’s fuel at any time. The specific gravity must read from .710 to
.780 at 60 degrees Fahrenheit, factored by a specific gravity temperature chart. Track Officials have the ability to conduct laboratory analysis of fuels. Samples for lab analysis may be taken from a competitor’s fuel tank at any time at the discretion of the Track Official Technical Inspector. If samples are taken, competitors must identify the specific brand of fuel they are utilizing. Any sample must meet the dielectric constant for the declared brand of fuel being used. FUEL WITH AN OCTANE RATING IN EXCESS OF 110 WILL BE SONSIDERED ILLIEGAL. The use of scent masking agents is not permitted and will be considered a fuel violation. Fuel must pass Germaine Engineering reagent A and D test any time. E85 fuel must meet DOT specifications for E85 motor fuel. Performance enhancing additives are not permitted.
FUEL SYSTEM Mechanical OEM push rod typed fuel pumps only. All cars must be equipped with a racing fuel cell. The maximum capacity of the fuel cell is 22 gallons, and a minimum of 20-guage steel. Fuel cell must be securely fastened, nonadjustable, in trunk area, behind rear tires, no further forward than the factory seam where rear frame rail can be replaced and must have a metal firewall between driver and fuel cell. Minimum height of bottom of fuel cell must be 12 inches at all times. The container must have (2 1” by 1/8” steel straps around all 4 sides. Fuel cell vents including cap vent must have check valves. Fuel lines placed through driver’s compartment must run through metal pipe or conduit. One fuel filter only and cannot be placed in driver’s compartment. Fuel cell vent hose must be below fuel cell.
IMCA type fuel flap mandatory.
•O.E.M. Automatic transmissions that match car make (G.M. in a G.M. or Ford in a Ford etc.). Vehicle must have two forward gears and one reverse, plus neutral. With engine running, car in still position must be able to engage car in forward and reverse gears without engine stopping. Torque converter must be unaltered O.E.M. or O.E.M. replacement (no dummy converters allowed). Torque converter must be a minimum of 10” at face. NO add on pumps to transmission. External transmission oil coolers are allowed. No transmission coolers allowed in driver’s compartment. Car must weigh 3100 lbs. After race with Driver
Manual Transmission Unaltered OEM 3 or 4 Speed (Cast Iron) ONLY and must have all gears working. With minimum 10.5” Steel/organic Single Disc Type Clutch and Steel Pressure Plate Assembly inside an explosion Proof Steel Bell Housing minimum 270 degrees around top of Clutch and Flywheel Area. No Light weight Bell housing allowed, Hydraulic clutch release bearing allowed. Steel Unaltered Flywheel ONLY and must be 16 LBS MINIMUM. Car must weigh 3300 lbs. after race with Driver.
Drive shaft must be O.E.M. steel, 2.5 inches in O.D., painted white with labeled with car number. All cars must be equipped with driveshaft hoop. The hoop must be constructed with .25 inch by 2-inch steel located 6 to 8 inches behind the front u-joint connected to the frame.
Mid plates are allowed
Only V-8 engines are permitted.602 crate engine is a legal option, and must meet the spec motor specifications. Please contact local representative for additional information. The maximum displacement for General Motors and Ford engines is 363.0 cubic inches. The maximum displacement for Mopar engines is 368.0 cubic inches. The maximum compression ratio is 10.80 to 1 for all engines. Engine mounts may be aftermarket. Engine must be in OEM location. For 1978-1987 GM frame and engine combination, center of GM fuel pump must be located minimum 1.75 inches in front of cross member. Ford metric frames must have back of fuel pump in front of cross member. Engine mount holes cannot be removed or altered on block. Aftermarket steel engine mounts allowed. Engine block must be a factory production cast iron block. Angle milling of block is prohibited. All engine block markings must remain.
Crankshaft and Harmonic Balancer Only OEM cast iron or forged steel crankshafts. Titanium crankshafts are prohibited. Lightweight, knife-edge, and undercut counterweight crankshafts are prohibited. Other aftermarket crankshafts may be permitted provided the journal diameter and stroke are the same as OEM. Only OEM, all steel, standard type harmonic balancers are permitted. Aluminum or fluid type balancers are prohibited.
Pistons and Rods any aftermarket piston, with the wrist pin in the stock location, may be used. Stock dimension wrist pins must be used. Only OEM magnetic steel, forged, connecting rods, O.E.M weight, no 6”. Any aftermarket magnetic steel, rod bolt may be used. Titanium rods and rod bolts are prohibited.
•Oil Pump, Pan, and Cooler Wet sump oil pumps only. Dry sump oil pumps are prohibited. Any aftermarket oil pan may be used. External engine oil coolers are permitted. Coolers may not be located in the driver’s compartment. Oil accumulators (Accusump’s) may not be located in the driver’s compartment.
All pans must have an one inch inspection hole located 16’’ from front of oil pan 1’’ down on driver’s side of motor. If no
inspection hole driver may be asked to remove pan for inspection.
Cylinder Heads. Cast iron cylinder heads only. Must be O.E.M. Stock or O.E.M. replacement parts. (Allowable head numbers are 014, 195, 267, 330, 336, 339, 388, 393, 441, 445, 454, 487, 493, 545, 598, 624, 642, 709, 799, 813, 862, 881, 882, 920, 991, 993, 997) or any other OEM stock replacement head that fits these criteria. General Motors Vortec (Casting P/N 10239906 or 12558062) and World Products SR #042670,042770,042750,043600, Heads must be 76cc. Engine Quest CH350I stock replacement cylinder heads are permitted. General Motors Vortec cylinder head P/N 25534351 & 25534371 are prohibited. Vortec heads may be drilled and tapped to install intake manifold. No Double hump, angle plug, bowtie, W-2, GT-40 or SVO heads are allowed. SPECIALLY PRODUCED LIMITED PRODUCTION PARTS SUCH AS CORVETTE Z-28, OR MARINE APPLICATIONS TYPES ARE NOT ALLOWED! Aluminum cylinder heads are prohibited. Titanium valves are prohibited. Cylinder heads must remain stock. All cylinder head markings must remain. Angle milling, chemical treating, acid dipping, acid flowing, abrasive blasting, bowl cutting, addition of material to the ports or combustion chamber, or other alterations to the original, as cast, head is prohibited. Valves, rocker studs, head bolts, and spark plugs may not be relocated. No polishing or grinding of ports or runners is permitted. No material may be added to the combustion chamber. A three-angle valve job may be done as long as no machining marks are more than 1/8” above the head of the valve. The maximum valve sizes, as measured across the face, are as follows: Manufacturer Intake Exhaust GENERAL MOTORS VORTEC 1.940 inches 1.500 inches ALL OTHER GM 2.020 inches 1.600 inches FORD CLEVELAND 2.046 inches 1.656 inches WINDSOR 1.8437 inches 1.5469 inches MOPAR 2.020 inches 1.625 inches Camshafts, Valve Lifters, & Rocker Arms o Stock production valve spring diameter for head used only and must appear OEM. NO Beehive or double springs. Roller camshaft bearings are prohibited. The maximum camshaft lift is 0.500 inches, measured at the valve retainer. Chain and sprocket camshaft drive system only. No roller tappets, or mushroom lifters are allowed. Valve spring retainers must be magnetic steel only. Rev kits and stud girdles are prohibited. Only steel push rods are allowed. Stock steel rocker arms or aluminum roller rockers are allowed.
•Intake manifold any cast iron, OEM, non-high rise, intake manifold is permitted. Grinding or polishing of the ports is prohibited. Chemical treating, acid dipping, acid flowing, abrasive blasting, addition of material, or other alterations to the original, as cast, intake manifold is prohibited. General Motors intake manifolds 14096242, 14096011, 14097494, and 12366573 are prohibited. One (1) inch, straight bore, phenolic or aluminum adapter plates may be used between the intake manifold and carburetor. INTAKE IMCA Crossover; Unaltered, approved OEM cast iron low rise, two- or four-barrel. Only aftermarket aluminum intakes allowed are: Wieland GM #7547, #7547-1; Ford #7515, #8023 or #7516; Chrysler
2020 Unified Dirt Street Stock Rules