What changes to make, for a driver?

[78SilvAnniv]

You're going about this the right way...

Safety, Reliability then Cosmetics.

We have been driving the 78 daily and year-round for most of the 13 years we've had her. (down-time for repairs and one Northern winter) Many "smiles per mile", and worth every $ spent!
I find her to be safe and very reliable. The key is Preventive Maintenance!
Fix it before you HAVE to. :bang

I'd be concerned with stopping, steering, suspension issues and seatbelt function first. This will make the vehicle driveable, safe and reliable, then other areas can be worked on.
Of course, this would only apply if you wish to drive while you restore.
Heidi

 

[Wamp]

wow

I am 100% positive that these are the stock exhaust heads that I am looking at and there is no koles for the air intake tubes. It had to have been a late 74 add on. my car is a dec 93 manufacture date. I have seen the air hook-up in manuels before just assumed that was a 75 thing along with killing the dual exhaust. If you look at the AIR hook-ups, they woulda been the first thing to go if they were on my car, talk about back pressure. a compressor hooked up to the heads for smog, yeah right...


wamp
74

 

[smurfvet]

Chevy used AIR systems on Corvettes from 1968. They were taken off "in the olden days" because lots of folks didn't understand them. I was one of them with a new Chevy van in 1972. Rik's corvette parts has a nice picture of the entire system on their website.

You probably have some older exhaust manifolds installed. This can be verified by finding the casting numbers on each, and researching what Chevy they went on. They are not the originals for the car, though. Use the NCRS pocket guide which has all these casting numbers and id tags listed for the car.

My exhaust manifolds have 4 - 1/4" pipe thread tappings in the manifolds close to the head connection point. These were normally plugged after the injection nozzles and manifolds were removed. There should also be a small (1/8" or so) hose coming off the original 4MV Q-jet on the front left of the carb that is plugged. This went to the pump control valve.

If your car had the AIR equipment removed and the manifolds changed, this plugged vacuum port on the original carb will be the only sign that the system existed. That is, if the original 4MV carb is still there

The AIR pump does not create backpressure, anyways nowhere as much as a restrictive exhaust can. A piston engine is a heck of a positive displacement pump! The pump injected a small amount of air into the exhaust manifold to burn whatever gasoline that made it through the cylinder after supposedly "complete" combustion occured inside the engine.

The AIR pump DID create a load on the engine though. This is what most folks at that time saw as unacceptable, the "drag" created by this pump.

So, off they came.

Anybody have a complete setup in their parts bin???

 

[GerryLP]

AIR Parts

Smurfvette and Wamp,

My 1981 Vette has most of the equipment (minus the re-circulating AIR tube from the catalitic converter-to-air pump). I have always concerned myself with maintaining the ability to register my vehicle in Smog-Nazi states (as Rare81 would say ). Living close of 18 years in California would do that to the most horsepower-hungry Vette-ego owner out there.

Removing all that stuff would probably give me a mil of a second improvement in quater-mile times, but I rather be able to maintain my vehicle practical when dealing with the EPA-born issue. That is why I purchased $$ :cry (and gave up new seat covers and foam) Edelbrok Performer Aluminum heads P/N0690 to compliment my new engine. These are legal in 50 states, and boast 2.02" intake valves, 64cc Chambers, and allow my "original" smog-related equipment to be installed back onto the car.

I got to tell you though, that the Vette restoration blues are common, and it is comforting to know that most of us are in the same boat (re-investing large amounts of $$$$ chaaacchinngg or mulla into these old cars)

 

[smurfvet]

Your system has the cat. the 74's were the last year w/o the cat (yay). You inject the air into the cat to assist combustion- same idea, different location. Hey Wamp, maybe that's the exhaust manifolds you have.

Good comment about the SmogNazis. That's the truth. New York has two levels of emissions testing- Below Yonkers, and the rest of the state. I drive the smurfvet down to Long Island, it won't pass the safety and emissions test. Can't register the car. I drive it outside Westchester County (1 hour horth of NYC) it's suddenly legal. Go figure. Same state, different rules.

Bucks is an issue, but we're all in the same boat. I found cross references to a number of parts that Chevy used on other cars. There's a lot to be said for interchangeability! It's funny how a old Corvette part costs 2 to 3X as much as the SAME part from a Chevy Nova. Except for major items (heads, intakes, exhaust, etc.) they even have the same id numbers. What if we were rebuilding some German thing??? OUCH