Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Poor idle

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Guadzilla:
Cliff, Keith,  Thanks I was afraid of that, so I can't expect a nice even 15 inches of vacuum at idle.  I have the timing as high as it can be without the idle falling off again at around 15.  Would a ram air IV speced quadrajet help. It has the original turbo 400 trans. Carb bogs when trans kicks down.
Thanks for your help.

Cliff Ruggles:
The real RAII and RAIV engines had high compression with very small combustion chambers in the heads.  Even with higher compression the real power curve really doesn't start coming on till past 3000rpm's or so.

Using a RAIV cam in a RAIII or lower compression build with "D" port heads just doesn't work well.  They don't have the good flowing round port heads and most of the combustion chambers, especially on the auto trans cars are quite a bit larger (lower compression) than what was used on a real RAII/RAIV engines.

I've had a good many brought here for custom tuning over the years and never once impressed with them anyplace.  With the auto trans engines you'd pretty much have to drop it off a floor jack at full throttle to do a decent burnout!  They fair a LOT better with a 4 speed application and pretty tall gearing but never on par with a real RAIV anyplace.

As far as tuning you can push the timing up and add idle fuel to get them to idle decent, but it doesn't change the laws of physics here, the real cure is a smaller cam or a lot more compression, higher stall converter (or manual transmission) and at least 3.90 rear gears........FWIW......Cliff

Guadzilla:
Thanks Cliff for your honesty.  I wish it had a 4 spd which goes in easy but it's a numbers car, so putting the right cam in is the logical approach.  So the cam is cuasing the rough vacuum osculation from 7 to 15 inches.  It will do burn outs if it doesn't bog and go 60 to 80 mph in a flash. 3.51 stock auto gears.  Try covering up the bowl vent on one these carbs. I have a 7042262 that I'm going to put on it to see if it acts the same.
Thanks
Tom

Cliff Ruggles:
The distributor could be adding to the issues.  The timing may be fluctuating some at idle speed.

Adding timing and idle fuel will help improve vacuum and idle quality.....

Guadzilla:
Timing light strobe is steady at idle.  Turning my idle mixture screws in and out barely has an effect on idle speed.

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