Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
new to forum. have issues with rebuild on new motor
soe1:
Hello everyone on the forum. I have enjoyed reading the very educational posts on this site as I dig into first attempt at a qjet rebuild and setup. I bought cliffs book and read through it a few times now. I am in the middle of tuning,re-tuning, etc. my setup is as follows. sbc 406. 11.2:1 comp. lunati voodoo cam 60103(227/233 at .05, .489/.505 lift. 110 lobe seperation, but ground 4 degrees advanced). I should have went with a different cam. qjet (17085230)dual capacity pump. single main air bleed setup as follows.I AM AT 5000 FT idle tubes-.039, idle down tubes-.062, upper idle-.07,lower idle bleed-.07,mixture holes-.103, idle bypass-.112, primary jet- .071/ needle 50m. light power piston spring. stock secondaries. float set at 1/4".
any help would be appreciated. soe
Cliff Ruggles:
So what is the problem?
soe1:
Cliff: opps. I forgot to mention my issues. My issues are. my idle air/fuel screws do nothing, which my have to do with the fact that no matter how lean I go with the main jet(71) with a 50m needle, it still seems to be too rich. I have done the rich/lean tests and all point to being too rich. My current jet/needle setup seems like it should be lean for the motor. I am starting to think that I have a fuel leak that causes this rich condition. Well plugs on the primary or secondary side?? The car runs way better than it did when I had 75/50m primary set, but it still loads up, my spark plugs show a somewhat rich burn. any suggestions would be greatly appreciated. soe
77cruiser:
How is the timing set up?
Cliff Ruggles:
First thing to do is to make sure the idle mixture screws are actually seating and have control of the idle fuel. I've seen a number of later Chevy truck carburetors where the threads weren't deep enough to allow the mixture screws to seat when you drill the holes that big.
Also take a look at the transfer slots. Many later truck carburetors have a LOT of idle transfer slot exposed provided quite a big of fuel to the engine at idle speed.
Look for nozzle drip at idle to make sure all the idle fuel is coming from the idle system.....Cliff
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