Chris O'

Is the air door supposed to open when the secondary butterflies are open? If I blip the throttle (in neutral) they won't open and fuel squirts on top of the flap. The vacuum operated diaphram holds the flaps shut the whole time.

Or does it only open when under load? The highers the revs, does vacuum go up or down?

Thanks

Ganey

No, do this:

TEST Sec. Operation
You should be able to see the air valve at least starting to open by: Engine HOT, air filter lid off, pull back hard on throttle for a moment.
Note: Sec. will not open w/ engine cold unless sec. lockout on pass. side has been bent out of the way.

A) Secondary air valve is held closed by vacuum when the engine is running at idle. If not, check vacuum hose on right (pass. side) front of carb.

B) Check that you have the right clearance on the rod that holds the sec. air valve closed w/ engine running, the clearance should be about .015-.020 or about the size of a pin.
This alone will fix many, you can try a little looser than this. This setting gets off slowly over time & adj. can unleash enough HP to make your car run like a Corvette.

There is also an air valve spring adjustment.

You may want to try TEST before & after adjustment if needed.

:cheers:


[Modified by Ganey, 8:09 PM 8/5/2001]

Jvette73

The secondary plate will only open under heavy engine load that creates low vacuum condition. Racing the engine in neutral will not usually create enough of a load to open the sec. The best way to check if there working is to wire the sec. shut. Then test drive the car. If there is a drop in performance with them wired shut, consider that they were working prior.

Chris O'

Thanks. Test was done hot with choke off. Will check the clearance. Had experienced a drop in power with hesitation at shift points (auto) at high revs.

May be crap fuel. I will have it dyno tuned when new cam goes in soon(?) with the new exhaust/headers. :D

clem zahrobsky

there is a stop on the sec air valve linkage that hits the carb body. put a small dab of grease on this spot,take a fast ride and check to see if the grease has a mark in it. :chevy