So I flipped the carb over and saw there is a screw inside the base that I guess acts as a stop for the secondary pump. It also opens the secondary blades (and not the primary ones)...

I noticed that the secondary blades were adjusted 1/16" below the transition slot, while the primary blades were adjusted so the very bottom of the transition slot was exposed. Only about 1/32"-1/16" of the primary slot was exposed...

So with the smallest screwdriver I had, I turned in that secondary screw so "slightly more then just the bottom end of the transition slot" was exposed. With the idle speed screw, I adjusted the primary blades so about the same amount of the primary transition slot was exposed below the blade...

I put the carb back on, and now it will not idle any less than 1200 rpms even with the idle speed screw all the way out. Turning the IAB screws in only raises the idle speed, but on the bright side, I'm getting close to 18"-20" of vacuum! lol

So my questions are am I on the right track with the secondary screw? Should I take the carb back off and reduce the amount of transition slot below the secondary blades? Should I leave it and concentrate on other possible things like timing (though I went from 10 back to 6 with no real effect) or turning the IAB screws out from 1 1/2 turns instead of in?

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Take the carb off again and reset all the barrels evenly but with less of the transition slot showing. try 1/64" or less. Temperarily disconnect all vacuum lines
and plug. (to eliminate potential leaks).
always reset the mixture screws for best vacuum. The idea is to have the motor idle on all 4 barrels evenly. Check your initial
timing. Check to see if advance weights are stuck in the distributer. Light advance springs, (curve kit) -will produce an unstable idle. You either have a very mild cam (strong vacuum)or you have an air leak somewhere. Do you have fast bleed down lifters (Magnum, Hi-Tech, Roads etc)
These will have a higher vacuum signal than a normal lifter. {Just checking the posibilitys.}

[This message has been edited by F-BIRD'88 (edited October 27, 2001).]

 

Check for damaged throttle blade(bent).
If you drilled the throttle blades now
that would make the idle speed faster.
Plug the egr passage in the plenum (under the carb). How does the exhaust smell with the barrels even. Even with it idleing too fast.

[This message has been edited by F-BIRD'88 (edited October 27, 2001).]

 

So I removed the carb about 6 times and ended up finally turning that damn screw which opens the secondary blades back to just about where it was in the beginning Maybe slightly more open then it was originally, but it doesn't expose any of the transition slot where it is... The idle speed screw doesn't really do anything (almost all the way out basically) now either. I imagine that would not happen if I turn the secondary blades ALL the way back to where I started with.

The only bonus I can see from this whole deal is that I can say I've turned every ****** screw, jet, and power valve on this damn thing and it still runs slightly rich. I'm going to check a few plugs again to confirm it is running rich, then I'm blaming the A/F gauge!

HEI is fine, plug wires all changed once... or twice, no vacuum leaks and about 14"-15" @ idle, no blades drilled, EGR blocked off, Rhodes lifters (I think)... I pretty sure it didn't run this rich with the Q-jet.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Which carb adapter plate ya got?
There has to be a vacuum leak you've overlooked. The motor is getting air from
somewhere else besides the carb. Something is being overlooked. Try another carb. Try your carb on another motor.
Don't throw your's against the wall yet.
Can you borrow one to try? This will eliminate the carb as a posibility.
Pefer another square flange carb (holley,
carter).

[This message has been edited by F-BIRD'88 (edited October 29, 2001).]

 

Did you read my post on the other thread about installing the secondary throttle stop screw from the topside? You could have adjusted it on the car,, with it running.