Stall/Idle dip in drive gear

[IHeartGroceries]

I'm a younger fellow, pretty new to carbs. I've a 1972 C-10 with a TH350, 350ci under the hood.
The truck has gotten to where it wants to stall out ONLY in drive gears, when at a complete stop or sitting idle. In park or neutral it runs alright. Not great, but not dipping in idle. I'm thinking a vac leak, but I want some educated guesses on where to look first.
Thanks!


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[buz48]

HI Whats your RPM read before you put it in gear should be around 7 to 800 rpm.. What brand of carb do you have?

[IHeartGroceries]

Originally Posted by buz48

HI Whats your RPM read before you put it in gear should be around 7 to 800 rpm.. What brand of carb do you have?

I do not have a tachometer on the truck. It is all original, Quadrajet Rochester, which I seriously doubt has ever been rebuilt. My trained ear would guess 1,000-1,100 RPM at idle in park or neutral. I had to raise it a tad at the idle air screw to keep her running in gears. Once in gear she's probably cling around 300-400 with periodic dips near stall. When I say she's all original, I'm mean down to the shocks. 113,000 original miles on drive train and chassis. Thanks for the reply.
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[cleszkie]

Is your timing set correctly? Base timing shoud be around 10 to 12 degrees of advance. Too much or too little advance can cause what you are experiencing. Smooth idle in neutral, but not enough power to idle smoothly in gear. Just my $0.02.

[PanelDeland]

I agree with the above.You probably need to put a timing light and maybe a tach/dwell meter on it to check idle speeds and timing.Once you know thats right,then you can check for a intake leak.You may find the leak with a check of the vac lines or you can try spraying the gasket areas of the intake with carb cleaner to see if the idle changes.The area where it does probably has a bad gasket.