Pure Stock / Thunder Stock cars please contact the raceway for information on racing at TSR


108” minimum wheelbase, American made stock production vehicles from 1955 to 1988 only.

No convertibles, or pony cars. Must be front engine, rear drive only.

Models with a full factory frame must retain that frame in stock position

Unibody models not allowed unless discussed with Tomah Sparta Raceway officials prior to construction.

X Brace allowed

Chassis must remain stock, full frame bumper to bumper (exception #7 below)

Rear frame rails, rearward of 6” behind axle centerline, can be replaced with square tubing.

Frame interchange not allowed

Frame must be original length, width, thickness, location, etc

Do not cut away any material from the factory frame

Do not reinforce the factory frame in any way which might obstruct, cover over, relocate, change, interfere with, etc any part of the frame such as spring pockets, body bolts, mounts, etc.

Leave the frame stock

All body mounting must be in stock location and attachment

Frame and rocker panels must be a minimum of 6” off the ground

All body components, including fenders, roof, cowl, doors, quarter panels, trunk lid, etc must remain in stock location and orientation & of steel material.

Rear spoiler are allowed.

All metal interior body work, such as floor, and front and rear firewalls, must stay intact. Rusted areas must be replaced with steel of similar thickness. Seal all holes.

Inner door material may be removed

No chopping of the roof to make it lower

No shortening of the fenders or quarters

No aluminum, fiberglass body parts allowed with tech approval, except for 5” maximum width aluminum rocker panel

Aftermarket plastic bumpers allowed..

Remove all cloth, plastic, vinyl, carpet, leather, etc., and any other non-essential flammable items

Air-conditioning, heaters, & radios must be removed. Remove all headlights, taillights, side markers, emblems, moldings, nameplates, & associated hardware

Front & rear seats & associated hardware must be removed

Stock hood & trunk latch must be replaced with pins, hood and trunk lid may be gutted & supports may be required by tech officials

Removal of trunk floor is allowed.

No sharp objects allowed anywhere in/on vehicle

No front air dams

Radiator air deflector-3” max. Width of radiator only

Safety hoop MANDATORY, on front half of drive shaft

Steel drive shaft only, 2 1/2” minimum diameter, painted white or bright color


No screen or half windshield permitted.

Windshield may remain factory glass or be replaced with 1/8” minimum thickness lexan.

All other glass must be removed

Rear windows are allowed

Rear side windows are allowed


Bumpers must be welded to vehicle

No cutting of bumpers or corners

Remove all trailer hitches

1” square tubing “rub rails” allowed between front and rear wheel wells. Ends must be chamfered and capped


Radiator protector no more than 4” in front of radiator and angled toward radiator

Radiator protector brace may be added, not to exceed 9” tall and may not extend outside the horns. Must be behind grill & immediately in front of radiator

All roll cage bars will be a minimum of 1 3/4” OD x .090” wall steel tubing.

No tail pipe tubing or water pipe allowed in roll cage

All cage joints require gussets welded in the corners

All cage connections shall be completely welded

Basic 4 point cage required

The bottoms of these bars are to be welded to the frame in the forward most corner of the interior and just behind the plane of the back seat.

A minimum of (2) side to side and (2) front to rear bars are required to give triangulated support to the 4 point roll cage

A minimum of (3) driver’s and (2) passenger door bars are required

All bars must be welded to the frame and to each other & NOT to the metal body work

Must have roof center bar

Driver’s door plate mandatory, 1/8” thick steel welded to door bars

No half or shorty cages

No bars of any kind may be mounted or extend outside the confines of the car body

Padding of roll cage bars near driver’s head, arms & legs are mandatory, and pad steering column

Installation of additional cage bars and supports are allowed to add additional strength to cage

Special note: Several local and national firms produce pre-cut and pre-bent cage pieces and kits especially designed for pure stock type race cars. These products may be stronger, less expensive, and more workable than home engineered bars.


Maximum compression to 9.5 to 1

“76” cc style heads only. See tech official for casting numbers that are legal.

Maximum cubic inch: Chevy 362 Ford 362 Mopar 373

Flat top or dish pistons only

Production type steel crankshaft with normal configuration counter weights required. No lightweight crankshafts.

No titanium parts of any kind

Must have inspection plug in oil pan: 3/4” NPT located in line with second or third rod journal of crankshaft, on either side above oil level. Hole in windage tray also required.

Oil pan may be no lower than bottom of cross-member. Options to correct are to add square tubing to bottom of cross-member, or raise motor.

Number 1 spark plug must be in line with or ahead of the upper ball joint centerline. GM 108” Metric chassis with engine in stock location, deduct 50 lbs.

All blocks, heads, manifolds (intake & exhaust) must be cast iron and remain untouched except for boring of block. No marine or bow-tie intake manifolds.

All camshafts and lifters must be hydraulic. No solid or roller cams

Hydraulic cam/lifters only. Maximum valve lift for all engines (GM, Ford & Mopar) is .420” at intake and exhaust.

No rev kits, roller rocker arms. Roller tip rocker arms are not allowed.

Lifters must be stock type hydraulic, and as installed and adjusted must bleed down .100”. No high dollar lifters allowed.

No aftermarket heads or manifolds

Maximum intake valve diameter is 1.94”

Body and engine manufacturer must match. All GM cars are allowed Chevy engines


No crate engines allowed


12 volt maximum battery

Stock type distributor & coil only. Firing order must not be altered.

No dual point distributors, or MSD boxes


Battery must be securely mounted (metal strap) behind driver in a marine style case.



No 2 barrel Holley 4412 only

1 1/4“ maximum thickness adapter and gasket combination allowed. Bore must not be tapered.

Carburetor must have air cleaner. No air boxes allowed

No tapered carb spacer plate


Completely stock cast iron exhaust manifolds only. No polishing, grinding or alterations allowed. Manifolds must exit downward, maximum 2 1/8” outlet. Center dumps are allowed(except Corvette).

No headers allowed

Exhaust must exit rear of driver’s compartment and under car to rear, not to side

System Options:

Dual exhaust with pipes and mufflers not to exceed 2 ½“ at any point

No 2 into 1 exhaust allowed

No X pipes allowed


Aluminum radiator allowed

Any radiator that can fit in normal stock location may be used

No modification to hood for radiator clearance is allowed

Some type of additional heavy duty screen must be used to protect radiator

A shroud around the outside diameter of the fan is required

Water only in radiator. No anti-freeze $50 FINE


Automatic transmissions only

Working stock torque converters only, with 12” minimum diameter

It is recommended to install 3/4” plug in rear cover above oil level, for inspection of differential, otherwise rear cover removal at the track may be required

Rear end must be stock for that make. No 9” Ford rear ends allowed

Aftermarket axle on right side highly recommended

All transmission rubber hoses must be sealed from driver

All gears must work

Must idle when in gear

All drain and inspection plugs must be safety wired. $50 fine for oiling up the track.


Front suspension components such as control arms, struts, hubs, etc. must remain stock and in stock location, mounted in stock position and manner for that make, model, and year. No after-market ball joints allowed. Oversize ball joints may be used. However distance from control arms to spindle must match stock for that make and model. Reaming of spindles is permitted in order to accomplish this.

Poly bushings allowed.

No rear sway bar components

Rear Suspension – stock only

Front sway bar must be mounted to frame in stock location. No shims allowed. Adjustments are to be made with the bolts in between sway bar eye and lower control arm. Maximum of 1 1/4” diameter sway bar. Sway bar must not be tubular, must be solid one piece bar.

One stock style shock per wheel, mounted in stock position, location and manner, non adjustable, non rebuildable, with 5/8” or smaller diameter shaft. Valving must be stock off the shelf, nationally advertised.

No tie rod or heim end shocks

Any steel spring that fits in stock location allowed

No adjustable (threaded type) spring spacers

Add stackable shims only, (allowed on front and rear springs)


Stock brakes only

No drilled, vented, j-hooked or directional vane rotors, (Coleman hubs OK)

No rear disc brakes

Brakes must be in working condition at all 4 wheels

Brake type must be stock for that make and model on all 4 wheels

One stock master cylinder only

Brake pedal must operate normally and be in stock location

Single piston calipers, no aluminum components of any kind

No made for racing brake calipers

One brake proportioning valve allowed, stock only

Wheel fans and brake blowers (electric fans) are not allowed


Minimum weight is 3400 lbs, with 53% minimum front, 42% minimum right side, with driver.

All added weights must be painted white and lettered with your car number. No tungsten, lead shot, ball bearing, or liquid type allowed. No moving weight or weight moving devices allowed.

No weights are permitted to extend or hang below frame



Vacuum fuel pumps only, no electric fuel pumps

Stock fuel tank must be removed. Fuel cells MANDATORY, 16 gallon maximum and must have 1/8” deflector plates on sides and rear

Fuel cells: must be securely mounted to the frame, be painted red, and be mounted so bottom of cell is a minimum of 11” above ground

Vents must contain rollover valves to prevent spillage

Fuel cell must have 1 3/4” diameter protector bar on rear, braced back to frame and extend below fuel cell

Gasoline only, no oxygenated additives allowed.


Used S800 tires only.

Maximum wheel width is 8”. ARE ALLOWED TO USE 8” WHEELS, WITH BACK SPACING OF 2” TO 5”

Stock wheels allowed on left side, steel racing wheels required on right side

Must use large 1” lug nuts, minimum five per wheel, threads must be visible on outside of lug nuts

Minimum wheel weight 19 lbs

Wheel offset (backspacing): 2” maximum. (1” back spaced wheels not allowed)


This division is meant to be an entry/learning level to racing. Drivers with experience in Late Models or higher divisions will not be allowed to compete in this division. At the promoter’s discretion noticeably superior cars may be subject to a handicap penalty consisting of weight and/or percentage changes. Rules trickle down from higher divisions, which means if it’s not legal in a Late Model, don’t expect it to be legal here, etc.

Ford and Chrysler vehicles will be allowed some variations to improve competition. ALL MODIFICATIONS MUST BE APPROVED BY TRACK OFFICIALS.


Helmet Snell SA-2005 (SFI 31.1 2005) or newer. Snell “M” helmets not allowed. Eye protection mandatory.

3” minimum width lap and shoulder harness, 2008 or newer. Crotch strap required.

Belts must be anchored to roll cage or frame. Belt anchors must swivel or be bolted solid pointing in same direction as when driver is belted in. Grade 5 hardware required.

Shoulder harness must not be anchored lower than 2” below driver’s shoulder height

Head and neck restraint, 6-point belts (double crotch strap) recommended

Fire retardant driving suit and gloves MANDATORY, driving shoes are recommended

Approved aluminum driver’s seat required, must be mounted to frame or cage as far from door bars as practical. Rib rest must remain flexible. Headrest support at rear of seat required.

Shoulder supports and head supports on right and left sides of seat recommended

Driver’s compartment must be sealed off from engine compartment and fuel container

Access to driver from right side by emergency personnel required

Securely mounted fully charged fire extinguisher, dial type required

Ribbon or mesh type window net with seat belt style release at front top cage upright required

Clearly labeled kill switch accessible from both sides of car required

Tomah Sparta Raceway officials will monitor items related to safety, but ultimately it is the responsibility of the driver to monitor, maintain, and update his safety equipment.


No tire treatments

No Nitrous Oxide, superchargers, turbochargers or fuel pressure systems

No aluminum blocks, heads or dry sump oil systems

In any and all circumstances, if part of your car is deemed by the tech staff not to support the stock specifications, it will be declared illegal at that time. You will lose points and money for the night. All parts in question must be removed immediately.

No anti-freeze: $50 FINE!

Two way radios are not allowed, one way “RACEceivers” required.

Team driving will be allowed, maximum of one car with two drivers per team. Championship points will be awarded to this team using the same rules as for individual driver cars. Teams wishing to do this must register as such with the promoter before the first night of the racing season. Each driver must race a minimum of three nights.

Championship points will be awarded per your finishing position. If drivers are disqualified, drivers behind them do not advance.

Tow Hooks: on front and rear required, painted bright color and/or labeled as TOW HOOK

Traveling cars will need to fill out home-track weight requirements.


A professional appearing paint job in an attractive color required. All lettering must be professional and in good taste. No duct tape or shake ‘n spray numbers.

18” high numbers on both doors and roof (readable from right side)

All dark colored cars must have ample light colored lettering or numbers to improve visibility

Headlight orbits must be tinned over and finished out. Attractive grille areas required.

No profanity/offensive lettering allowed.


All cars are subject to inspection ANYTIME before, during, or after a race

Officials reserve the right to disqualify cars, require changes, confiscate illegal parts etc. The decision of the officials is final, and will be based upon fair play, safety, and to protect the “Spirit of Stock Car Racing”

Any interference with any official(s) and his/her duties will result in an automatic disqualification

Official’s decisions will be based upon fair play, safety, and to protect the “Spirit of Stock Car Racing”

Disqualification (except weight violation) is retroactive to ALL previous events competed in that race meet

Non-compliance with the rules outlined here will subject the participants (owner/driver) to disqualification

All non-complying components will be seized by track officials

Any driver/owner refusing to allow the track officials to inspect a car will lose points and money earned and will have the subject car impounded until inspection is performed with crew chief and driver present

Owner/driver must provide tools