2021 Rules Amendment
Sportsman Cars – (Formerly Limited Sportsman)
Add to Section 9.7
Rebuildable shocks per NASCAR Late Model rules per Section 20F-12.3 will be allowed as an option in the Sportsman class with a weight penalty of 70 lbs with at least 35 lbs of that on the right side. If rebuildable shocks are used they must be used on both the front and rear of the car.
In addition to the weight penalty, a claimer rule of $250 per rebuildable shock will be allowed in the Sportsman class. Claims will be allowed for front shocks ($500 for both) or all four shocks ($1,000). A competitor wishing to claim shocks must finish no more than two positions behind the winning competitor whose shocks are to be claimed. Backward claims are not allowed. All such claims must be made in writing to the class official within 20 minutes of the race finish and the money associated with the claim must accompany the written claim request when it is presented.
Revise Section 9.2 as follows:
All sportsman cars running the P/N #24502609-ZZ4 or P/N #88958603 or #88958602 must weigh a minimum of 3100 lbs total and a minimum of 1400 lbs on the right side with the driver in the car. A ¾ lb per lap allowance will be used for determining the weight after completion of race.
All Sportsman cars running the P/N #88958604 must weigh a minimum of 3150 lbs total and a minimum of 1425 lbs on the right side with the driver in the car. A ¾ lb per lap allowance will be used for determining the weight after completion of race.
All sportsman cars running a built steelhead motor must weigh a minimum of 3150 lbs total and a minimum of 1425 lbs on the right side with the driver in the car. A ¾ lb per lap allowance will be used for determining the weight after completion of race.
Revise Section 9.3 as follows:
Title of section will be “Sportsman Engines”.
Revise Section 9.3 A as follows:
The P/M #24222502609-ZZ4 or P/N #88958603, the P/N #88958602 and the P/N #88958604 crate engines will be allowed in the Sportsman Class with the carburetors defined in Section 9.4 A herein.
Built steel head engines will be allowed in the Sportsman Class in accordance with the specifications defined Section 9.9 herein with the carburetor defined in Section 9.4 A herein.
Revise Section 9.4 A as follows:
Holley four (4) barrel, model number 80507-1, 390 cfm will be used for the 224502609-ZZ4 or P/N #88958603 engine. No machine work allowed. Jets and power valve may be changed as long as the replacement parts are manufactured by Holley. A one piece solid aluminum carburetor spacer, one inch maximum thickness may be installed between the intake manifold and the carburetor. Spacer must be centered on the intake manifold and may be open or the four (4) hole type. No tapers bevels or any modifications permitted.
Holley four (4) barrel, model number 80541-1 or -2, 650 cfm will be used for the P/N #88958602 engine. No machine work allowed. Jets and power valve may be changed as long as the replacement parts are manufactured by Holley. A one piece solid aluminum carburetor spacer, one inch maximum thickness may be installed between the intake manifold and the carburetor. Spacer must be centered on the intake manifold and may be open or the four (4) hole type. No tapers bevels or any modifications permitted.
Holley two (2) barrel, 450 cfm will be used for the P/N #88958604 engine. The 450 cfm carburetor consists of a 500 cfm, P/N 80583-1, main body and a 350 cfm, P/N 7748 or 80787-1, throttle plate. No machine work allowed. Jets and power valve may be changed as long as the replacement parts are manufactured by Holley. A one piece solid aluminum carburetor spacer, one inch maximum thickness may be installed between the intake manifold and the carburetor. Spacer must be centered on the intake manifold and may be open or the two (2) hole type. No tapers bevels or any modifications permitted.
Holley two (2) barrel, model number 07448 or 80787-1, 350 cfm carburetor will be run on a built steel head motors. No machine work allowed. Jets, power valve and accelerator pump may be changed as long as the replacement parts are manufactured by Holley. A one piece solid aluminum carburetor spacer, minimum of 0.700 inch and a maximum of 0.750 inch in thickness must be installed between the intake manifold and the carburetor. Spacer must be centered on the intake manifold and must have the two (2) holes that match the base of the carburetor. No tapers bevels or any modifications permitted.
Add to Section 9.5 C
When new tires are purchased on the buy weeks, they must be run that race and will be required to be run on the left side only.
Add Section 9.9 as follows:
9.9 - Detailed Built Engine Requirements
Built engines must conform the following detailed engine requirements. Changes from the approved standard production automobiles or components parts will not be permitted except as specified in the following rules for engine preparation.
9.9.1 – Engine Location
General Motors open/built engines must be located so the center of the forward most spark plug hole on the right side of the engine block is in line with or a maximum of one (1) forward of the right front upper ball joint. The ford open/built must be located so that the front of the cylinder head on the right side is in line or a maximum of one (1) forward of the right front upper ball joint.
9.9.2 – Engine Ground Clearance
The engine ground clearance will be measured (with the driver) from center of the crankshaft accessory drive bolt. A minimum of 12 inches and maximum of 13 inches from center of crankshaft accessory drive bolt to ground must be maintained at all times.
9.9-3 – Engine Mounts
All engine mounts must be acceptable to Track Officials and meet the following minimum requirements:
A. All engine mounts must be reinforced steel or aluminum.
B. All engine mounts must be securely bolted.
Adjustable engine mounts will not be permitted.
9.9.4 – Engine Displacement
A. The cubic inch displacement will be as follows:
CUBIC INCH MAXIMUM
MANUFACTURER DISPLACEMENT OVERBORE
Ford 351 CID 0.050 inch
General Motors 350 CID 0.045 inch
B. The manufacturer’s stock bore and stroke nominal dimensions for the approved engines are listed as follows:
MANUFACTURER BORE STROKE
Ford 4 inches 3.500 inches
General Motors 4 inches 3.480 inches
C. The formula for determining cubic inch displacement is as follows; Bore x Bore x Stroke x 0.7854 equals cubic inch displacement of each cylinder. The cubic inch displacement of each cylinder added together will determine the total cubic inch displacement of the engine.
D. Unless otherwise permitted by Track Officials, a maximum cooling down time of two (2) hours from the official completion of the Race will be permitted prior to measuring the total cubic inch displacement.
9.9.5 – Engine Blocks
All engine blocks must be acceptable to Track Officials and meet the following minimum requirements. Track Officials may use an engine block provided by the respective manufacturer as a guide in determining whether a Competitor’s engine block conforms to the specifications of the ‘Rule Book
9.9.5.1 – Eligibility
A. Engine block must be a product of the manufacturer of the make of the approved engine being used for competition.
B. Aftermarket engine blocks will not be permitted.
C. The engine block must retain the standard external dimensions with the exception of the maximum allowable overbore and the surfacing of the engine block deck. Angle cutting of the engine block deck will not be permitted. Removal of material from the engine block with the intent of weight reduction will not be permitted.
D. Only cast iron engine blocks will be permitted. Aluminum or compacted graphite engine blocks will not be permitted.
E. The engine block deck height, measured from the center of the crankshaft main bearing journal to the top of the engine block where the cylinder heads bolt on, must be as follows:
MANUFACTURER BLOCK DECK HEIGHT
Ford 9.200 inches (minimum 9.080 inches)
General Motors 9.000 inches (minimum 8.980 inches)
Any engine block deck height below he minimum tolerance may be assessed a weight penalty of five (5) pounds for every 0.010 inch up to o.o5o inch below the minimum tolerance. Any engine block deck height more than below 0.050 inch minimum tolerance may be assessed a weight penalty of 50 pounds.
9.9.5.2 – Internal Changes
Internal polishing of thee engine block will not be permitted. Deburring of casting flash from the engine block will be permitted.
9.9.5.3 – Piston/Rods
A. All pistons must be configured with two (2) separate compression piston ring grooves located near the top of the piston and one (1) oil ring groove located below the compression ring grooves. A piston compression ring must be uses in each compression ring groove and one (1) oil ring groove assembly must be used in the oil ring groove.
B. Any flat top three (3) ring round aluminum piston with three (3) rings will be permitted. Minimum compression ring nominal width is 0.043 inch and the minimum oil ring nominal width is 3mm (0.118inch). Valve reliefs for valve clearance only may be cut into the pistons.. The piston must not protrude above the top of the engine block surface. The use of coatings on the piston will not be permitted.
C. Only magnetic steel piston pins maintaining a minimum diameter of 0.927 inch will be permitted.
D. Piston pin holes must be in a fixed location in the piston and connecting rods.
E. Only two-piece insert style rod bearings will be permitted. Roller bearings will not be permitted.
F. Only solid magnetic steel connecting rods will be permitted. Hollow beam connecting rods will not be permitted. All rods must maintain the minimum/maximum rod lengths listed below:
MANUFACTURER MINIMUM MAXIMUM
Ford “Cleveland” 5.778 inches 6.250 inches
General Motors 5.700 inches 6.250 inches
G. Titanium and stainless steel connecting rods will mot be permitted.
H. Connecting rods must be machined to normal machining schedule utilized for standard production parts. Piston guided rods will not be permitted. Spacers or shims will not be permitted between the piston boss and the connecting rod. The maximum side clearance between the connecting rods will be 0.035 inch.
9.9.5.4 – Oil Pans/ Oil Coolers
The oil pan and oil coolers must be acceptable to Track Officials and meet the following requirements:
A. Oil pans must be made of magnetic steel.
B. The oil pan must be a wet sump type and manufactured using a standard production type pan with only a sump reservoir added to the bottom. All bolt holes and bolt hole flanges must be visible. Kick-outs will not be permitted between the bolt on flange and the top of the added sump. Spacers, other than sealing gaskets, will not be permitted between the oil pan side rails and the engine block surface.
C. Engine oil coolers may be either an oil to air or an oil to water heat exchanger mounted forward of the engine firewall. Air ducts will not be permitted. All oil coolers and the installation must be acceptable to Track Officials.
9.9.6 – Cylinder Heads
A. All cylinder heads must be approved and all modifications must be presented to Track Officials before any proposed modification will be eligible for approval. Approved manufacturers’ identification and part numbers must remain unaltered on the cylinder head being used in competition. The following heads are approved for competition:
MANUFACTURER PART NUMBER CASTING NUMBER
Ford M-6049-N351 M-6049-N351
General Motors 10134392 14011034
(Current design) 12480034 12480034
World Products
Sportsman II SBC 011150 1-037
(Current design with mfg. date stamped on head)
The approved cylinder heads above must conform to all of the requirements of Section 5.6 through Section 5.6.3 herein.
Track Officials may use a cylinder head provided by the respective manufacturer as a guide in determining whether a Competitor’s cylinder head conforms to the specifications of the Rule Book
B. Heating pads, blankets or any other heating devices will not be permitted for warming the heads.
9.9.6.1 – Eligibililty
To be eligible, the cylinder must be acceptable to Track Officials and meet the following requirements:
A. Cylinder heads must be stock cast iron production only and approved by NASCAR, and are limited to two (2) valves per cylinder.
B. The valve angle must remain as approved by NASCAR and be acceptable to Track Officials. The following are the acceptable valve angles permitted:
MANUFACTURER VALVE ANGLE
Ford 10 Degree
General Motors 23 Degree
World Products Sportsman II SBC 23 Degree
C. All valves must be identical in appearance and construction as an OEM valve. Titanium or exotic material valves will not b permitted. Air directional devices will not be permitted on any of the valve surfaces. The valve stems must have a minimum diameter of 11/32 inch. The valve stem diameter may be undercut to a minimum diameter of 0.302 inch in the area of the valve stem from the head of the valve to the bottom of the valve guide. Hollow valve stems will not be permitted.
The maximum valve sizes as measured across the face of the valve are as follows:
Ford Intake - 2.020 inch Exhaust – 1.600 inch
General Motors Intake – 2.020 inch Exhaust – 1.625 inch
D. A maximum of three (3) valve angles plus the bowl cut will be permitted. When cutting the valve seat angles, stone or grinding marks will not be permitted above the bottom of the valve guide. All cutting in reference to the valve job and bowl area must be centered off the centerline of the valve guide. Radius cuts will not be permitted. Upon completion of the valve job, the bowl area above the valve seat must 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. When replacement valve guide bushings are installed the valve guide boss must retain the same shape and configuration as it was from the manufacturer.
E. Titanium valve springs will not be permitted. Only magnetic steel valve springs will be permitted.
F. Port matching or flow work will not be permitted.
G. Angle cutting of the cylinder head to the engine block mating surface will not be permitted.
H. The cylinder head stud or bolt holes must not be offset or drilled off-center for the purpose of moving the cylinder head in any direction.
I. “O” rings will not be permitted for sealing the cylinder head to the engine block.
9.9.6.2 - External Changes
A. External modifications will not be permitted.
B. All cylinder heads are limited to a minimum of 62 cc combustion chamber for each cylinder. The combustion chamber may be machined cut, on the walls beside the valve only, to equalize chamber cc. Any other machining or grinding will not be permitted. Removal of material from the cylinder head, with the intent of weight reduction, will not be permitted.
9.9.6.3 – Internal Changes
Internal polishing, porting and/or any other internal modifications will not be permitted.
9.9.7 - Crankshaft/Harmonic Balancer
9.9.7.1 – Crankshaft
A. Only standard magnetic steel or cast iron production design crankshafts will be permitted. If aftermarket crankshafts are used, they must be designed and manufactured the same as OEM crankshaft for the approved standard production engine. Stroke must be increased or decreased. Balancing will be permitted. A solid material must be used to balance the crankshaft.
B. Only two-piece insert style crankshaft bearings will be permitted. Roller bearings will not be permitted.
C. Counterweights must be the same shape, may be polished, but they must not be knife-edged, undercut, or drilled to lighten the crankshaft. The rod bearing journals may be drilled. The main bearing journals must not be drilled.
When weighing crankshafts, the minimum weights listed below shall include the timing chain sprocket. The following dimensions are the minimum specification for al crankshafts:
MANUFACTURER Main Journal Rod Journal Weight
Ford 2.750 minus 0.030 2.100 minus 0.030 50 Pounds
General Motors 2.450 minus 0.030 2.100 minus 0.030 50 Pounds
9.9.7.2 – Harmonic Balancer
A. Harmonic balancers must be used and must be used as manufactured and be acceptable to Track Officials. Only standard OEM magnetic steel elastomer type harmonic balancers will be permitted. The use of :O” rings or other devised that deviate from the standard OEM elastomer rubber insert will not be permitted. Outer covers, lops, etc. to prevent the separation of the outer ring will be permitted provided they do not deviate from the standard OEM elastomer rubber insert.
B. Electronic switching devices or sensors will be permitted on the harmonic balancer, crankshaft or flywheel.
9.9.8 – Camshaft/Valve Lifters/Rocker Arms
9.9.8.1 – Camshaft
A. Only magnetic steel camshafts will be permitted. The camshaft bearing journal size must be the same as the standard production design for the NASCAR approved engine being used.
B. Only standard production timing chains will be permitted. Belt drive and gear drive systems will not be permitted. Camshaft timing must be fixed, variable timing devices will not be permitted.
C. Only standard production sleeve type cam bearings will be permitted and must be the standard inside diameter for the NASCAR approved engine being used. The cam bearing bores in the block may be machined a maximum of 0.030 inch oversize from standard bore. Needle or roller bearings will not be permitted.
D. Camshafts must be driven in the same direction of rotation as the NASCAR approved production engine being used. The camshaft must maintain the same firing order as the NASAR approved production engine.
The approved firing orders using approved cylinder identification are as follows:
Ford 1-3-7-2-6-5-4-8
General Motors 1-8-4-3-6-5-7-2
E. The manufacturer’s cylinder identification sequence is as follows:
General Motors Ford
(Front) (Front)
1 2 5 1
3 4 6 2
5 6 7 3
7 8 8 4
F. The front engine cover material must be acceptable to Track Officials.
9.9.8.2 – Valve Lifters
A. Only solid magnetic steel or magnetic steel hydraulic valve lifters will be permitted. Roller tappet, ceramic valve lifters, mushroom valve lifters and any type of mechanical assistance exerting a force to assist in closing the valve and/or rush roc, commonly referred to as rev-kits will not be permitted.
B. Only flat tappet straight barrel lifters will be permitted. Lifters must be the same diameter and length as the original equipment for the approved standard production engine.
C. Only magnetic steel one-piece, pressed together valve push rods, without any moving parts, will be permitted.
D. the standard production push rod guide plates will be the only guide plates permitted.
9.9.8.3 – Rocker Arms/Valve Covers
A. Only steel or aluminum rockers arms, one (1) per valve, that are acceptable to Track Officials.
B. Roller rocker arms will be permitted. Rocker arms for all General Motors and Ford cars must be an independent single stud type. Dual shaft rocker arms will not be permitted. Offset rocker arms will not be permitted with the exception of the Ford part number M-6049-N351. Stud girdles will be permitted. All aftermarket rocker arms assemblies must be acceptable to Track Officials.
C. Valve covers must be made of steel or aluminum. Magnesium and other exotic material will not be permitted.
9.9.9 – Intake Manifolds
A. The intake manifold must be approved by NASCAR. The approved manufacturer’s identification in the form of cast-in part numbers must remain unaltered on the intake manifold.
B. Track Officials may use an intake manifold provided by the respective manufacturer as a guide in determining whether a Competitor’s intake manifold comforms to the specifications of the rule Book.
C. The eligible manifolds must remain as manufactured. Listed below are the only eligible intake manifolds for the Sportsman division competition:
MANUFACTURER PART NUMBER
Ford Ford Performer – M-9424-C358
General Motors Edelbrock – 2101
All Edelbrock part numbers are current design Edelbrock Performer Series Intake Manifolds. Older design intake manifolds with the same part number will not be permitted.
D. For all manufacturers approved intake manifolds, the front to rear center divider of the intake manifold may be machined to a minimum width of 1/8 inch at the top of the divider for clearance with the throttle bore holes in the adapter plate. The machining must be an angle cut from the minimum width on each side at the top of the divider and blended to the manufactured width on each side at a maximum blended depth of ½ inch down into the plenum area. This is the only machining that will be permitted to the intake manifold. The remainder of the intake manifold must remain as manufactured.
E. The intake manifold material msut be aluminum. Magnesium or other exotic materials will not be permitted.
F. Port matching or flow work will not be permitted.
G. Only one (1) standard flat gasket, a maximum compressed thickness of 0.075 inch, may be used between the cylinder head and the intake manifold.
H. Intake manifolds must be painted or coated.
Super Street
No changes beyond what was made in the 2020 rulebook
Mod-4
Change Section 11.5.6 C (10) as follows
Only Holley metering blocks can be used. Surfacing of the metering blocks for improved gasket seal will be permitted.
UCAR
Page 38 - Add Note beneath U-Car Weights and % Rules With Driver as follows:
NOTE: Motor Mile reserves the right to adjust weights and % rules at anytime to equalize competition.
Page 38 – Revise weight paragraph as follows:
All lead weight will double bolted with Grade 8 or higher bolts, nylon lock nuts and 1 ½” inch fender washer or 1” x 1” square 1/4” thick blocks required beneath the head and nut of bolts. All lead weight must be mounted beneath the car located 3 inches inside of right side pinch weld starting 10 inches behind right front wheel opening and approved by track officials. All lead weight must be painted white and have car number and class on weight.
Page 39 – Revise paragraph that defines allowable bodies as follows:
Completely stock for that make and model (body, frame, suspension, steering, pedals, brakes, etc.). Fabricated magnetic steel doors and aftermarket bumper cover (nose) allowed.
Page 39 – Revise paragraph for engine allowable as follows:
Four (4) cylinder engine must be for the same year and model as chassis and remain stock with a 0.020” maximum allowance for cleanup of head.
Page 39 – Revise power steering allowable:
Power steering is optional.
Page 40 – Revise UCAR tire Rules as follows:
UCAR TIRE RULE
Hoosier 790 Tire will be an option. A maximum of 8 Hoosier tires will be branded for competition. Hoosier tires branded must only be used on the car for which they were bought.
All four tires must be the same size. Racing wheels are allowed.
All four wheels must be the same size, style and offset. Offset on racing wheels must be 3 inches or higher. Maximum wheel width will be 7 inches
No altering of tread pattern by any means allowed.
No altering of tire compounds by any means allowed. No armor-all, tire dressing, tire conditioners, softener, etc.
Motor Mile Speedway and/or officials reserve the right to ban any tire if deemed a competition advantage or unsafe.
