Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Hard start hot

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442:
I have a hard start hot/flooding 1969 442, orig carb 7029253. I got cliffs well plug repair kit, the 10-32 plugs and sealant, marine tex. Did the primaries, secondaries are always dry, but put some marine tex over them anyways.
Job went well. Still does it and I've had the carb off lots of times, set float low (on purpose), new needle and seat, new float. 0
I let it sit for a while hot, pull the carb off, it looks like the pass side primary well plug is wet (actually looks like it's coming from just above the well plug and the pocket area, if that's possible).
I have blasted the well plug with compressed air and soap, I can't get any bubbles- going from either direction. Any tips?
Thanks, Chuck

Cliff Ruggles:
 Remove the main casting and put it on the work bench or elevate so you can see the bottom plugs.

Leave the needle/seat in the carb and fill it with fuel.

Keep checking the bottom of the carb and see if any fuel leaks from either side in the front.   I've seen a few castings develop leaks internally allowing fuel from the main fuel bowl into the passage leading down to the idle mixture screws.

It's pretty rare but to date I've had 3 carbs in here now that failed that test and we had to replace them.

Another issue that causes difficult hot restarts and a flooded condition is leaking UNDER the fuel inlet seat at the gasket or gasket surface.  After shut down even the smallest leak can allow the fuel bowl to continue to fill if there is still pressure in the line up from the pump.  A tiny leak at the needle will basically do the same thing.

Very small leaks may not show up when running the engine as the fuel is consumed at a faster rate than the leak. 

I get carbs in here ALL THE TIME with these sort of issues.  I test them by filling the fuel bowl with a soap/water mix and pressurizing the inlet at the filter housing.  I leave the float and hinge pin in place and hold the pin down firmly.  Any small leak shows up as a stream of bubbles........Cliff

442:
Any reason you can think of for fuel to be coming out of this hole? thanks

Cliff Ruggles:
If fuel is coming out of that hole it's making it's way from the main fuel bowl to the passage that leads from the DCR to the baseplate, which is NOT GOOD!

This indicates that the casting is compromised between the fuel bowl and the idle fuel passages in the main casting.

That's what I was talking about in my first response......Cliff

442:
Well dang, numbers matching carb.
Is it possible that there's an incorrect gasket or air horn (that hole goes all the way up to the air horn as you know.
I ask because when I first got the car, it also had a nasty off idle bog, replaced accel pump/rebuild.. all that.
Then I noticed I had no adjuster for APT (in the base plate under the power piston). So I assumed the rebuilder before me put a later baseplate on. Found an older baseplate with the apt, adjusted and now no more bog/hesitation. Actually runs like a swiss watch with the exception of this hot hard/flood start.
If they weren't paying enough attention to the correct base plate, what makes me think the air horn and gasket are correct?

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