Finding those 1/1000's.

           I strongly encourage you to get a copy of whatever rules apply to your class. The SCCA rules allow certain modifications for Stock class cars, then Street Prepared allows more mods on top of those. The term "free" roughly means any part you can make fit is legal, as long as it will bolt on to the intended mounting spot and performs the same function, or can be mounted just by drilling holes and bolting it on.

In fact, even if you're not planning on running the car in any sort of event, but just want a quicker street car, this can be a good place to start. When you include the Stinger parts, the allowable modifications list is long and touches on just about every facet of the car's performance.

Caveat: This table is based on the '96 rule book. I will update it for the newer rules when I get a new book.

Stock class.

       First, let's cover the allowable mods for Stock class, as given in Section 13 of the SCCA Solo I & II rulebook. I've only listed some of the rules, giving a short interpretation here of each rule which seems to apply to Corvairs and how a Corvair could be modified.
  • 13.2.A: Accesories and "comfort and convenience" items which don't lighten or change the performance of the car are free. This includes things like stereos, shift knobs, window tinting, etc.
  • 13.2.C: Gas caps are free.
  • 13.2.E: Corvairs may use any steering wheel that varies no more than +/- 1" from stock.
  • 13.2F: You may remove the spare, jack, and lug wrench.
  • 13.2.G: Roll bars and cages are legal, but only 4 point roll bars may be welded in.
  • 13.2.I/J: A trailer hitch and/or towing brackets may be added.
  • 13.3 covers tires. Roughly, the tires must be DOT legal, not stick out from the fenders, and the fenders may not be trimmed for clearance.
  • 13.4: Wheels. Must be of stock size +/- 1/4" backspacing.
  • 13.5: Shocks are free.
  • 13.6: Brake shoes are free.
  • 13.7.A: Front sway bars (only) are free.
  • 13.8: The suspension may be adjusted to its limits. Also, cars with swing axles (early models) may be lowered to achieve up to two degrees of negative camber.
  • 13.9.A: Plugs, points, coil, and wires are free.
  • 13.9.B: Cars built prior to 1 Jan 68 can have any ignition as long as it uses a stock distributor. I'd say that something like an MSD system triggered by the points is therefore legal. An Allison system might be legal, but don't change the advance curve.
  • 13.9.C: Ignition settings are free.
  • 13.10.A: Air filters are free, as long as it fits in the stock housing.
  • 13.10.B: Overboring up to +0.020" is allowed.
  • 13.10.E: The exhaust system downstream of the cast iron manifold is free.
  • 13.10.F: Oil filters are free.
  • 13.10.L: Oils and greases are free.
For Corsa events, the rules are somewhat different, but not by too much. See section 8.1 of the Corsa autocross rules. Significant changes to the above are:
  • 8.1.4: Tires may not be "R" type or have a wear rating less than 140, and must be of 75, 78, or 80 series.
  • 8.1.5: Camber compensators are legal on early models
  • 8.1.7: Updating/backdating of suspension components within early or late series is legal.
  • 8.1.8: Cornering modifications to carburetors and oil pans are legal as long as they are not obvious.
Not legal are:
  • Front sway bars changes, other than interchanges on earlies.
  • Only mufflers may be changed on the exhaust system.
  • Ignition changes.
  • Steering wheel changes.

Street Prepared section.

          There are quite a few mods allowable under the current SCCA rules for Street Prepared, section 14 covers them. The listing for the Corvair in the appendix includes all years of Corvairs, and stages I, II, and III of Yenko Stingers. When I discuss Corvairs in the text, it includes the Stingers.
  • 14.1.C: Allows updating/backdating. This means you can *bolt* any part from any other 'Vair onto your car, however this does not include modifying the car to accept the part. Therefore, swapping an engine from a late to an early is legal, but swapping in the late model rear suspension is not. Speaking of engine swaps, the engine, trans, and diff must be swapped as a unit, i.e., you may not put a 102 cam in a 140. You may, however, run a "304" factory turbo cam, since that was the last service part available.
  • 14.2.A: Fenders may be modified for tire clearance. This includes rolling the fender lips, but be careful if you trim off the entire lip, as the fenders on a Corvair are part of the structure. Since a full roll cage is not legal, you will need to tie the fenders and fenderwells back together for strength.
  • 14.2.C: Strut bars are legal, but they can only run straight across. This may not be an obvious mod for a Corvair, but it should be possible to stiffen the car with a bar tying the frame rails together at the suspension mounting points.
  • 14.2.D: Any seat is legal.
  • 14.2.E: Any steering wheel is legal. See Seth Emerson's articles in the Corsa Tech Guide about wheel swapping.
  • 14.2.F: Spoilers, but not skirts, are legal. See the rule text for specifics on size.
  • 14.3: Tires. Basically, any DOT legal tire is allowed, which includes the various "R" series tires.
  • 14.4: Wheels. Anything you can bolt on :-) Flaring and cutting for clearance is legal.
  • 14.6: Brakes. Dual master cylinder conversions, boosters, and proportioning valves are free, but not disk brake conversions. Since drums are lighter anyway, this isn't really a problem.
  • 14.7: Sway bars are free.
  • 14.8.A: Ride height is free, but can only be changed by cutting the springs, adding spacers, or modifying the perches. The springs themselves are free, but must be of the same type (sorry, no coil-overs). On '64's, the leaf spring is also free, and you can update an earlier 'Vair with one if you wish.
  • 14.8.C: Bushings are free, but cannot be changed to metal or spherical joints.
  • 14.9.A: Ignition is free.
  • 14.9.B & 14.9.C: The battery is free and it can be relocated to the trunk, but must still be 12 volts.
  • 14.9.D: Any bolt in starter and generator/alternator is allowed, as long as the alternator has an output greater than or equal to stock (30A for earlies, 37A for lates). It might be possible to adapt a new, lighter starter to the Corvair starter nose.
  • 14.10.A: Oil pumps, pans, pickups, coolers, and filters are free. An accusump may be added, but dry sumps are not allowed.
  • 14.10.C: Carburators and FI systems which can be bolted on are free. Turbos may *not* be modified in any way (sorry).
  • 14.10.D: The air cleaner housing is free.
  • 14.10.E: Emission controls are free.
  • 14.10.F: Water injection is legal.
  • 14.10.G: Fuel lines and pumps are free. Cool cans are *not* legal.
  • 14.10.H: The exhaust is free,as long as it is quiet. One reason to make the effort to seal those headers.
  • 14.10.I: A bolt on torque supressor is legal. A nice way to do this would be to run a rod from the lifting eye on the bellhousing to the driver's side frame rail.
  • 14.10.J: Fan and shroud are free, including electric fans.
  • 14.10.L: Clutch, flywheels, and torque convertors are free.
  • 14.10.M: Any mechanical shifter is legal.
  • 14.10.N: Limited slips diffs are legal.
  • 14.10.P: Balancing the engine is legal.

Frequently Asked Questions.


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Last update: 18 February 2000. Copyright Bryan Blackwell.