I'm culling these out of e-mail I've gotten in response to these pages, and postings on Virtual Vairs.
A: This is probably the number one problem with autocrossing Corvairs, some folks have problems on their street cars as well. For Stock and SP cars, you'll be best off making the stock system work, if everything is as it should be, the belt will stay on. For all out Prepared or Mod cars, you may need some mods to keep the belt on. In general, the stock system should be fine up to 6000 rpm without any troubles. Take a look at the fan page for more info.
Q: As far as rules for the Street Prepared Class, what sort of modifications are allowed to the heads. From what I can tell, it is nothing except porting. No high rate springs, no roller rockers. Is this correct? Can anything be done to increase RPM range?
A: Actually, you can't do anything at all to the heads. You are correct, no rockers, springs, pushrods, or porting past 1" down the head. You have a special case, however, read on.
Q: Since intakes and carburetors are unrestricted does this mean that the integral intake on the Corvair head can be shaved off to add triple Webers (the best Carburetion available). I have been told that this is not allowed. If not, can the point where the carburetor attaches to the manifold be cut wider (this is about 4 or 5 inches from the valves)?
A: No to both. HOWEVER,
In the SCCA classes, the classification line reads Corvair (all), Yenko Stinger Stage I, II, III. Under the update/backdate rules, you can swap in a Stage II or III engine, which had ported heads! Now, to be legal, you must also use all the other parts and build a complete engine, no mixing and matching. Unfortunately, you are still stuck with the stock intake, though you can bore the holes (Stage III) for bigger carbs, and you must use the valve springs to match the cam.
Q. My car does not currently have a interior. Race seat only. Does that force me into a special class? Am I missing something here or do I just have to read between the lines?
A: In general, both Corsa and SCCA rules work as follows: If it isn't listed as being legal, then it's not, so if there's nothing about changing the seats, then you can't.
So technically, yes, you'd go straight to Prepared. If you add a second seat, some carpet, that would be close enough to a Stinger interior for E/SP. See below for a more general answer.
Q. The car has four 8" wheels and two 10" wheels. There seems to be a difference between SCCA and CORSA on the use of wheels?
A: Yes, there is, I'd need to re-read the Corsa rules to tell you exactly what, in general a built to the limit SCCA E/SP car goes to Corsa Street Mod, and C/P goes to Competition. Because of the points system in Corsa's Improved Stock, a partially modified E/SP car will be legal, as the individual mods are allowed. I would mention that it's probably better to worry about SCCA rules, rather than Corsa rules, as there are more SCCA events than Corsa events, and just about all the serious folks there will also have built to SCCA rules.
Let me mention something, tho. Don't get too hung up in being 100% legal when you get to that first event, or what class you're running in. Just about every non-stock car being run the first time has *something* that is technically illegal. Unless you've got a really pro driver, and you've done a really good job sorting the car, you're going to be, ahem, a bit off the pace, so no one's going to really worry about it. Just be sure that when you're starting to run in the first couple spots that the car is legal. If you're really concerned, run the car in a 'Fun' class, or run it in Modified. Main concern (to me, anyway) is stuff like not breaking, staying on course, developing the car, learning to drive, etc.
I ran a pretty good season two years ago, went to a whole bunch of events. There was a guy there with a nicely set up Stock class 95 horse Monza coupe. It took me the entire season to get my SP class 140 Corsa to run as fast as his car.