[M Zeigler]

I need some suggestions, replaced the stock quadrajet 4bbl that needs a significant rebuild, (can't adjust idle air mixture)
installed the new carb, idle was extremely high, checked the timing, set it at 8* BTDC, idle was set right around 600 - 700 RPM, as soon as the truck is put into gear, idle drops , engine labors, not enough vacuum for the power brakes, runs great on the road.
No issues like this before.

Thanks, Mike

 

[David Ray]

There are umpteen versions of carb pads and bases for those setups, very easy to get the wrong casket package, wrong gasket stack.

Got a propane torch? If so, use it UNLIT, UNLIT, MAKE SURE IT IS UNLIT, flow UNLIT propane around the base of the carb. Idle gets better, carb to manifold leaks, possibly wrong gasket stack

And, Initial timing is 8 degrees, what is the idle degrees of timing) combination of initial and vacuum advance added degrees) ???? .

 

[Leadhead]

Definitely vacuum leak. You sure you don't have an open port somewhere on the carb?

 

[oldcutlass]

What distributor are you using? Initial timing settings are determined by the amount of mechanical advance built into a distributor.

 

[Leadhead]

Was the idle dropping that low when you put it in gear before you replaced the carb?

 

[Tom Mobley]

so you pulled off the perfect carb for it and installed some universal POS and now it runs bad? imagine that. What did you use to adapt the the edle-faucet to the Q-jet manifold? problem is likely there.

Can you still get the Q back?

 

[Malibu70]

Initial timing set with vacuum advance disconnected? Is the distributor vacuum advance can attached to the carburetor manifold port on the front right, or the ported line on the front upper left?
Low vacuum at idle will allow the PCV valve to open and present a large vacuum leak when the engine can't compensate at idle rpm.
Where is the power brake vacuum line attached, at the rear of the carburetor, or from the top of the intake manifold at the factory fitting?

 

[David Ray]

OK, square bore carb to Q-Jet manifold, needs two gaskets and Edelbroke 2732 adapter plate to seal off the carb to the inlet manifold.

Please outline initial timing, vacuum advance added idle degrees, total degrees (initial and mechanical curves added together).