This is not a SPEARS Southwest Tour Series points event; the rules are specific and unique to the Winter Showdown. The SPEARS Southwest Tour Series Rule Book is NOT in force, except for body rules, the ‘9.5:1 Tour’ engine specifications and driver safety specifications.


  1. BODIES: The ABC (Approved Body Configuration) Official Rule Book Version 9.0 and the 2015 SPEARS Southwest Tour Series Rule Book will govern body regulations. In the event of a conflict between the two rulebooks, the body rules of the Spears SRL Southwest Tour Series rule book shall prevail in body regulations. The use of factory (ARP & Five Star) ABC rocker panels only.
  2. WEIGHT: 2900 lbs. – base weight of all cars
  • Weights include driver, race ready with fuel on board.
  • All added weight must be made of lead (no tungsten) securely fastened, white with car number.
  • Perimeter Chassis 58.0% max. left side weight at all times.
  • Straight Frame Rail Chassis 57.0% max. left side weight at all times.
  1. TRACK WIDTH: Measured at spindle height on the inside wheel bead of the right wheel (rearward) and at the outside wheel bead of the left wheel.
  • 66” maximum all cars.
  1. STRAIGHT FRAME RAIL CARS: Any chassis measuring less than 56 inches outside to outside from frame rail to frame rail will be considered a straight-frame rail chassis – 57.0% max. left side weight & max. track width 66”.
  2. ENGINE:
  • Maximum c.i. = 362 (Ford, Chevy) • Chrysler = 365 cu. inch – steel blocks only.
  • Over 362 to 380 c.i. add 50 lbs. / 381 to 400 c.i. add 75lbs. Over 362 c.i. must have prior approval.
  • NOTE: The CRA legal 390 carburetor is allowed – Booster bar removed.


SRL Tour legal 9.5:1 engine with CRA legal 390 carburetor.

(See SRL Rulebook for Engine Specifications)


Brodix Spec Head

  • Gauge legal 750 carburetor* for Chevrolet.
  • Gauge legal 750 carburetor* for Ford – with the All Star Performance Adjustable Base Plate with the 1.400” inserts.
  • Only part numbers – Brodix SP – CH / FO / MO – will be allowed
  • All Spec heads will be supplied with CNC bowl blend and intake port matching.
  • No grinding or blending of CNC work is allowed.
  • No grinding or polishing of any kind is allowed anywhere on the castings.
  • No use of any substance that may change or alter the shape or the size of ports or combustion chambers is allowed.
  • Maximum 1-inch port match allowed to manifold.
  • A maximum valve size of 2.080 intake and 1.600 exhaust will be allowed for all Spec heads.
  • Valve seats and guides are to remain as manufactured and in their cast positions.
  • The original seat center locations as provided by the head manufacturer may not be altered.
  • No tapering or re-shaping of valve guides will be allowed.
  • No titanium springs, steel only.
  • Titanium valves approved.
  • A minimum combustion chamber volume will be 60 cc.
  • Minimum valve stem diameter is 11/32”.
  • Spec cylinder head serial numbers must remain on the head and may not be defaced or altered.
  • No welding modifications are allowed to the original head castings.


Approved McGunegill, Hamner, Progressive, SSPE or other approved “S.E.A.L. Engines” at 2,900lbs. All approved S.E.A.L and SSPE engines must use the gauge legal, 750 Holley carburetor*, or CRA 390 carburetor.

  • Any tampering of seals or established construction of these engines is grounds for immediate disqualification. 7600 maximum RPM limits (SSPE 8000). Rev limiting device must be operational at all times with RPM Dials securely covered.
  • All cars using the approved S.E.A.L. – McGunegill, Hamner, Progressive or SSPE must only use the following ignition system: ONE Crane Cams Ignition part# 6000-6700 (HI-6RC) and a Coil part# 730-0192 (PS92N), mounted on a tray as from Crane Cams, as far to the right and forward as possible inside the car. RPM dial positioned facing right side of car.


  • All 750 Carburetors must be an unaltered 750 CFM 4779, 80528 Holley*. Gauge Legal.
  • Engines with rear mounted distributors will be located so the forward most spark plug is no more than two inches (2”) from the center line of the upper ball joints. Engines with front mounted distributors: up to four inches (4”) setback from centerline of upper ball joints. All engines center of the crankshaft must be within one (1) inch of the centerline of car. 10 inches min. crank height.
  • NOTE: Other engine configurations may be approved, with weight adjustments.
  • IGNITION BOX and WIRING: For all cars – ONE ignition box must be mounted as far to the right and forward as possible inside the car, all wires in plain view and out of reach of the driver. All wires to the distributor must be run separately and not part of a bigger loom or wiring harness. All wiring must be sealed. No unplugged wiring. Only one box allowed.
  1. FUEL: Sunoco Purple 110 Standard is the Spec fuel of the event. No blending – must be pure.
  2. TIRES: Tires must be purchased from Hoosier Tire West 559-485-4612. Hoosier 56* Rights / F45 Lefts. May be pre-ordered and picked up at event.
  • Your four qualifying tires will be used to start the qualifying race. Four approved tires for the start of the feature and four approved race tires used at the half-way break will be impounded and released at designated times. LCQ – Four approved tires.
  • Must qualify, start, and finish, on approved tires purchased only at the event from Hoosier Tire West.   Practice on any Hoosier 56* Rights / F45 Lefts from Hoosier Tire West.
  • Flats must be replaced with approved race tires. Unapproved tire change is (2) lap penalty per tire. Official must inspect a flat tire before team removes and changes.
  • No performance enhancing or appearance enhancing products allowed inside or outside the tires.
  • Maximum 10” wide steel wheels only.
  • Bleeders are not allowed.
  1. OTHER:
  • Roll cage must be constructed of 1 3⁄4” OD round steel tubing with a minimum wall thickness of .090”. Three inches (3”) maximum gussets measured diagonally must be welded in main roll cage area where a 90 degree angle exists or where the roll cage meets the main frame rails. The main frame rails / bolt-on clips must be steel from radiator area to behind the fuel cell. Main Frame rails must be a minimum of 2” x 3” rectangular steel.
  • No titanium parts – unless stated.
  • No Carbon Fiber – radiator ductwork, brake fans, rotors, or clutches.
  • Interiors sheet metal must be magnetic steel or aluminum only.
  • Full standard type transmission only will be permitted. No quick-change transmissions will be permitted. Automatic transmissions will not be permitted. A minimum of one reverse and two forward gears will be required. Multi-disc clutches will be permitted. No direct drives. Conventional clutch mounted to fly wheel only will be permitted. No carbon fiber or nonstandard material clutches. The minimum clutch

diameter is 5.5”. No “slipper” or “centrifugal” clutches allowed.

  • No fifth (5th) coil, or lift bar suspensions will be permitted. No birdcage set-ups of any kind (3 or 4 link). Trailing arms must mount to rear end in a solid fashion (heim allowed) and no part of the trailing arm mounting may freely rotate around the rear end.
  • Springs, shock absorbers, or any dampening devices will not be allowed on the lower trailing arms or upper third link.
  • No cockpit driver adjustments, other than brake bias.
  • Coil Springs and Spindles must be Steel. (Exception: approved Coleman Spindle)
  • One shock per wheel. Shocks must be only mechanical in nature and no part of

suspension or shocks may utilize electricity.

  • The duct work between the nose and the radiator may be no wider than 29” and may not be carbon fiber.

No types of under-body air deflectors or panning allowed. All air for brake blowers or coolers in the engine compartment must be pulled from the nose or the radiator air box. Air may not be blown or forced onto the tire or bead, air may only be directed to the brake rotors. No air pulled from under the car.

  • A reinforcement plate of not less than 14 gauge (.078 inch thick) magnetic steel flat plate or similar strength aluminum plate, between fuel cell and rear end and be securely welded in place or bolted (min. 3/8 diameter bolts) with two (2) bolts on each side. A similar plate at the rear of the fuel cell is highly recommended. At a minimum, all fuel cell configurations must include a rubber type cell in a steel container. Fuel Cell Height: 8 inch min.
  • Added weight must not be located ahead of the front spindles or behind the centerline of the rear axle.
  • Two-way radio communication between driver and minimum of one spotter for each team is required for all competitors at all times while on track. Each spotter must have a radio that will scan Race Control frequency at 460.0125.
  • NO Traction Control Devices of any kind – If any ‘traction control’ device is found, the driver and owner will be disqualified from the event, the car will be confiscated until a $15,000 fine is paid. Additionally, the driver and owner will receive a lifetime ban from all SRL events.
  • No electronic recording devices allowed in or on the car – (cameras may be approved.)
  • A minimum ground clearance of four (4) inches on any part of the frame, suspension or body (excluding front cross member). Cross member must have a minimum clearance of three (3) inches. The crossmember is the only part of the car allowed at (3) inches.
  • A muffler must be used and installed in a configuration that will suppress exhaust noise to a maximum of 99db’s at 100 feet.
  • Transponder: All competitors must have timing transponders on their car for the entire program. Transponder must be mounted 24 inches (center of axle tube to the center of transponder) behind the rear axle housing on outside of right side frame rail. Transponders are mandatory for practice sessions. Available at event.



This is not a SPEARS Southwest Tour Series event, the rules are specific and unique to the Winter Showdown. The SPEARS Southwest Tour Series Rule Book is NOT in force, except, 9.5 to 1 engine rules, body rules and driver safety specifications.


“We all share the responsibility to make this a marquee event that we will all look forward to being part of for many years to come – Thank You.”


For more information go to www.SRLSouthwestTour.com,

call the SRL Office at 661-679-4681, or email lcollins@mesamarin.com.