Sad day in automotive history

[Greg_L]

Well 12.20 isn't that impressive and it's certainly not fast enough to reveal the limitations of IRS on a dragstrip. Quite a few 60's era muscle cars could have ticked off 12's if they had any tires that were worth a darn. Instead they ran 14's on skinny bias play junk.

I knew a few 9 second late model vette guys and they ran those times in spite of their IRS. They certainly aren't hitting the tires hard. It's a relatively mild launch and then GO! Pretty funny really. They're like those index racers in the NHRA. Take off, slow down, then go! Still, 9 seconds is fast. They'd get better ETs though with a better rear end.

But anyway, it's apples and oranges. I do like Corvairs. They're a cool piece of automotive history.

[zarfnober]

Well 12.20 isn't that impressive and it's certainly not fast enough to reveal the limitations of IRS on a dragstrip. Quite a few 60's era muscle cars could have ticked off 12's if they had any tires that were worth a darn. Instead they ran 14's on skinny bias play junk.

Road tests on a 70-1/2 Z28 got nothing better than low 15's. My brother ran 12.75 on slicks, traction bars and open headers, otherwise stock. He was more than surprised! And he beat my oldest brother in a grudge match on that particular run, race car was in the 10's. My older brothers girlfriend was rooting for the winner! That was back at Oswego Dragway, I think the first NHRA sanctioned strip, it's a tree farm now.

Rocco

[Greg_L]

Yup, that was the beauty of those cars. I took very little to make them go much faster. My GTO ran 12.80's stock with just slicks and a better ignition, carb, and intake. It then went through a myriad of engines and trannies with the best setup running a 10.78 @ 129. Then I spun a rod bearing street racing and it's been sitting in the garage ever since.

[zarfnober]

So, Gas Tires and lots of Oil? Never spun a bearing, but have bent connecting rods and wrist pins in a Vair, even spun a crank gear once(25 ton press fit too). Everyone else gets the normal, for a Corvair anyway, dropped valve seat or holed piston, or broken differential. Not me. Boost is fun, and addicting.

Rocco

[Greg_L]

So, Gas Tires and lots of Oil? Never spun a bearing, but have bent connecting rods and wrist pins in a Vair, even spun a crank gear once(25 ton press fit too). Everyone else gets the normal, for a Corvair anyway, dropped valve seat or holed piston, or broken differential. Not me. Boost is fun, and addicting.

Rocco

Pontiacs are notorious for bad connecting rods. They're almost like a built-in rev limiter that gives you one warning and then it's kaput. 6500-7000 rpm is really pushing it for stock Poncho rods even in a well built engine. I can't even tell you how many junkyard crawls I've done looking for 455's, and then upon finding one having my excitement tempered by a connecting rod sticking through the side of the block. Sucks. The serious Pontiac engine builder uses aftermarket steel rods or better yet, aftermarket big block Chevy rods. A BBC and Pontiac connecting rod has the same width at the journal end. BBC rods are cheap, plentiful, and come in many different lengths. The only drawback is you must offset grind the Pontiac crank journals down to BBC size, and use custom pistons. Neither process is a big deal if you're building a serious performance Pontiac engine, but it's not stuff for the weekend street warrior.

Pontiacs are the best non-Chevy GM engines though. Much better than Buick or Olds.

[zarfnober]

The Vairs big problems are: HP heads drop valve seats and they need a fair amount of work to flow good, due to the exhaust port/stack location. We remove the stock port/stack and bore out at an angle to get them to flow on the ex side. Intake requires milling away cast-in manifold, carefully porting and welding on individual runners for triple Webers. Valve seats need to be "hi-press fit" with a deeper and wider seat, some guys use copper/berylium. Mill heads for higher compression, which ends up requiring shorter push rods OR, get custom made pistons, which is fortunately easy to do now. Rods are 99.99% of the time not a problem, and most Vairs will never see enough power to bend them. Unless of course you have something go wrong under boost. Crankshafts are perfectly happy up to 6,500 for as long as you want to spin it, beyond that a stock one needs a FluidDamper for extended road racing. A few guys have made billet/counter balanced cranks, expensive. Cooling system is not the best, but works, need an externally mounted oil cooler for road racing. Some guys use a vertical fan similar to Porsche, but believe it or not, the stock belt sytem only throws belts when wrong belt is used, pulleys seriously out of alignment or belt is just installed too tight. Too tight is the most common reason, they actually gotta be a little loose. Camshaft gears need to be set screwed, crank gears need to be pinned.

No one ever made an aftermarket head for the Vair, which really sucks. A great majority of the stuff we use has to be custom made, again, easier to do nowadays, just expensive.

We also use 94mm VW pistons and cylinders to get 190 cu in, only takes money and machine work!

Other than the above, they're a piece of cake, count your blessings!

Rocco

[Greg_L]

Cool, didn't know that stuff about Corvair engines. I think it's very interesting how each engine from back in the day had it's own set of nuances and tricks to make them better. Even in the same auto division - Chevy, Pontiac, Buick, etc, each had their own line-ups of engines. About the only thing that interchanges on a Chevy, Pontiac, Olds, etc engine is the distributor rotor. Everything else is unique. Now that things are corporate, everything is one-size-fits-all. I hate that. There's no personality with cars anymore.

Head porting and valve seat work is pretty common to any "race" engine though. Heads as-cast are very rarely worth a darn - especially vintage stock junk. Valve angles are cut for longevity and simplicity and nothing else. Unfortunately corporate engine designers didn't understand air flow back in the day. It took racers like Grumpy Jenkins and Smokey Yunick to really popularize head porting and air flow. In retrospect it seems too easy. You need to burn fuel to make power, you need air to burn fuel, more air means burning more fuel which means more power! Simple! Engineers still to this day don't have it figured out. I've done heads for years. They still leave a lot of meat on the bone. Actually the nazis had it figured out long before that. Their Messerschmitt planes used nitrous oxide to make more power and outrun the allies. That's obviously not head porting, but they understood that more air means more fuel and that means more power. The allies tried to keep up by adding more blades to their propellers. Doh!

[zarfnober]

Late models used Chevelle front brakes on the rear(due to rear weight bias), and rear brakes on the front. A handful of other parts were shared with other Chevys, but not much.

Stock Vair engines when not "repaired" by some moron, rarely have any major problems, they just didn't make enough power to break. As for the valve seats, this was Chevys 2nd(the first was a copper engine) air cooled engine, and they are the one thing that they are notorious for dropping. Usually caused by overheating. Mostly on the high perf heads.

One of these days I'll get some work done on mine!

Rocco