k5714x4

I have an 85 Z28 that will hesitate at wot, but will go away by backing off the throttle a little bit. I have rebuilt the carb, changed the tps, replaced all the ignition parts and no luck. It also has a rough idle, almost feels like a miss but goes away above idle.

84TAProject

hows the tension on your a/v flap? It may be opening to fast. Its an easy check, and can cause a car to bog if to loose.

five7kid

iTrader: (14)

Did this appear suddenly, along with the idle miss, perhaps?

There are two things that help prevent a "bog" when first opening up the secondaries: The choke pull-off, and the air valve (AV) tension spring mentioned above. In that order.

If the choke pull-off has failed, it will allow the AV to slam open, causing this "bog" or hesitation. This occurs because the air flow occurs before the fuel can catch up, hence a lean condition. As vacuum falls with increased air flow, the choke pull-off releases. Then, the AV tension takes over for the final regulation. A failed choke pull-off will also cause a lean condition at idle on some cylinders, therefore the miss.

Other than that, make sure your ignition is up to snuff, and timing set correctly (slightly more advance can decrease a bogging tendancy).

k5714x4

Thanks, I adjusted the a/v and the hesitation is gone. I think the idle is better as well. Thanks again

five7kid

iTrader: (14)

You adjusted the AV tension and the idle improved????