BODIES:
Bodies must be stock appearing, mounted per manufacturers guidelines, and must pass through INSSA body jig.
Professional appearance must be maintained. Fiberglass or aluminum only, no carbon fiber. No body skirting or streamlining will be allowed.
• Approved bodies: 1998-2006 with standard quarter panels & 2006 A-B-C bodies. Others by approval. No Downforce bodied cars or altered body panels will be allowed. Frame & body clearance 4" min. without driver. 47" roof height required. Rear spoiler max. 6.5" x 60", clear Lexan.

TREAD WIDTH:
Maximum
Stock Stub: 69"
Fabricated Big Spring:* 67"
Fabricated w/ coil-overs: 65"
(*Big Spring means 4-3/4"min. diameter, front & rear)
 

WEIGHT:
Stock stub: 2950 lbs, 58% left side
Fabricated Big Spring: 2950 lbs, 58% left side
Fabricated w/coil-overs: 2950 lbs, 58% left side
Wt. Penalties:
• Oversize Engines >360cid: add 100lbs & minus 1% left
 

MOTOR:
• Cast iron approved blocks only. Engine must match body: GM-to-GM, Ford-to-Ford, etc. Centerline of crankshaft must be within 1" of the centerline of the tread width. Engine set back: GM - 2", Ford and Mopar - 3"; measured from the most forward spark plug hole to the centerline of the upper ball joints. Crank height minimum 10". Dry Sump systems allowed.
• Flat tappet cams only; no roller, mushroom, or radius-bottom lifters allowed. Lifters must be .875 max for Ford and Chevy, and .904 max for Chrysler.
• "Standard" aluminum open-plenum intake manifolds only with no flow improvement work or drilling allowed. Maximum ½" gasket matching permitted on intake. Maximum intake height, measured from plenum floor to include carburetor spacer and gaskets may not exceed 5-1/8".
• Any 4-barrel carburetor permitted.
• Distributor type ignition only, no magnetos.
• Maximum exhaust sound level 95 db @ 100 feet. NO TOLERANCE!

FRAME & SUSPENSION:
• Frame must be minimum 3" x 2" square tubing – .120 wall thickness. Roll cage must be constructed of minimum 1-3/4" tubing – .090 wall thickness.
• Minimum wheelbase 101"
• Stock Stub cars must have at least 12" of stock frame horn ahead of spindle centerline and the front lower control arms must be stock without modification. Lower A-frame rear-mount must mount to stock frame. Bushings and ball joints may be changed as long as original dimensions are not altered.
• Big Spring cars must have shocks mounted outboard of the coil springs, not inside the spring.
• Adjustable shocks are allowed. Only one shock per wheel. No remote reservoir or remote adjustable shocks permitted.
• Major steering components including tie rods, drag links, centerlink, spindles etc, must be OEM or fabricated steel. Aluminum heim joints are not permitted.
• Rack and pinion allowed with aluminum tie-rods.
• One piece tubular trailing arms only; no spring-loaded trailing arms or shock-dampened third links allowed. No rear sway bars permitted. No cambered rear axle housings.
• No shock, spring, or weight adjusting devices will be allowed in the driver’s compartment.
• Added weight must be securely mounted, painted white with car number. Solid block lead only, no pellets or liquid.
• No devices for shifting weight will be permitted.
• No electronic traction control devices permitted. Officials reserve the right to exchange any ignition boxes, tachometers, etc. Any driver caught with a traction control device will lose all season accumulated points and be suspended indefinitely.
• Steel racing wheels only, maximum width 10".