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Old 04-13-2012, 01:05 PM
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quadra-jet idle issues

My quadra-jet on my 75 L48 vette was having problems idling so I took it to my guy to work on it found that 1 of the metering rod tip was broken he replaced it. I put it back on the car now it won't idle and smells really rich I had turned up the idle before I took it to be fixed and it would idle then now it won't idle at all. The carb and motor are both stock with headers and dual exhaust. The carb was rebuilt 2 years ago and ran good until this spring.

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Old 04-21-2012, 07:09 PM
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Maybe you missed a vacuum hose? just a thought.
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Old 04-21-2012, 07:23 PM
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Quote:
Originally Posted by bbrazkey
My quadra-jet on my 75 L48 vette was having problems idling so I took it to my guy to work on it found that 1 of the metering rod tip was broken he replaced it. I put it back on the car now it won't idle and smells really rich I had turned up the idle before I took it to be fixed and it would idle then now it won't idle at all. The carb and motor are both stock with headers and dual exhaust. The carb was rebuilt 2 years ago and ran good until this spring.
Check to be sure the vacuum advance hose was put back like it was before, and not on a different vacuum port. If, for example, you were using manifold (full time) vacuum before, and after the carb was R&R'd the vacuum hose was put on a ported vacuum port (no vacuum at idle), that would cause the idle speed to drop way down and could make it run poorly until it was off idle.

Was the piece of metering rod that broke off (that's a new one on me!!!) ever recovered? The passages are relatively small in areas, having the piece of metering rod in the jet or elsewhere could cause problems- but it wouldn't make it run rich. Was it a primary or secondary rod that was broken, and do you know how it got that way?

Of course, there's a chance the repair caused the problem like if a gasket tore (were the old gaskets reused?) or if it was assembled wrong- like if the power piston is stuck in the "up" (full rich) position, or if the wrong length primary metering rod was used (there were two different lengths).

Another possibility is the float level was accidentally changed to be too high, or if teflon tape had been used before, the threads from the tape might have fouled the needle and seat.

In any event, the carb will need to come back apart if the vacuum lines or something similar isn't the cause. I would caution you against driving it like this- if it's running pig-rich, the excess fuel will wash the lubrication from the cylinder walls and that's death to the ring seal.
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Old 04-21-2012, 07:33 PM
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My bad, skipped right over the rich part.
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