auto_cran

I just picked up an 84 Corvette (auto/Z51). Good running car - I'm impressed with the L83. This is the 3rd C4 I've owned (others being an '88 and an '89)

So can someone tell me (or tell me where to go) to learn how the Air Induction System works? I'm talking about the 2 solenoid operated flaps on the sides of the air-cleaner housing.

Mainly when do they open/close? And with the car off should they be open or closed?

Searches revealed most owners just leave them open. But I never found a good explanation on how and when the operate.

thanks in advance!

Chris

84 4+3

Basically drivers side flap is controlled by the thermac. There is a temperature sensitive valve in the intake that once it is sufficiently warm, the driver side flap opens. When it is cold, air is pulled from the heater pipe that runs to the exhaust manifold as this is still a wet flow system and the warm air helps keep the fuel in suspension while the intake manifold is cold. The passenger side flap is closed unless there isn't sufficient vacuum to hold it shut. For example when you floor it. This allows for extra air flow at high rpms. When the engine is off they should both be open. That is about all I know. It's kind of like a choke I suppose. Basically it maintains an idealized intake charge temperature. (Kind of...)

Hot Rod Roy

Glad to hear the good news about your new '84! Welcome to the very exclusive "One Year Only" '84 owners club! It took me a while to figure out that air cleaner arrangement, too! Here's a link (see post #6):

https://www.corvetteforum.com/forums...post1595999417



Looks like 84 4+3 is a faster typist than I am! The flaps are definitely not like a choke, though. There's plenty of air available. You certainly wouldn't want to "choke" a good running warm engine!

(Now I've got it! He's on East Coast Time!)

84 4+3

Nah I'm just a wizard or something traveling through space and time.

And the choke thing wasn't serious. It kind of acts like one when you first start it but not really. The correct word was preheater. I'm a little tired.

Tom400CFI

These guys nailed it on how the "THERMAC" system operates. You may want to have a look at THIS THREAD, too.

Hot Rod Roy

The proto '83 'vette's had that extra hole in the top of the radiator intake plenum, but they eliminated it for the final configuration '84 because they had problems with sucking rainwater and road splash into the hood ducts. That may not be a problem for a "fair weather" car, but GM decided that opening was a bad idea.

The '83 in the Corvette Museum has that opening.

auto_cran

Thanks everyone for clearing this up! I now have a good understanding on it's purpose and how it operates.

thanks again!

Chris