fuel leak at carb, help!

ibjoe · Jul 26, 2001

I replaced the 2bbl carb on my '73 with a recycled Quadrajet. Works great except there is a leak where the line meets the inlet. The original steel line (flared end) went into a brass 90* fitting into the carb. With slight bending the line fits into the Q-Jet fuel inlet fitting (that big 1" piece). But there is a slight leak, line to fitting, no matter how tight I make it. I tried 2 different inlet fittings, they both leak.

I guess the original steel line was happy with the brass fitting, and is not quite right with the (steel?) Q-Jet inlet fittings. Mechanically they look the same. Why does it leak? Are both the (used) inlet fittings bad? Is there a way to recondition the steel flared line (my countersink bit maybe?). Does the Q-Jet inlet not work with steel lines, should there be brass or copper (the line didn't leak with the 2bbl brass fitting). Is there any type of gasket I could use?

Worse case, I could use a brass barb fitting, cut the steel line, and run a piece of rubber fuel line, but I'd rather have the steel line go straight in.

Ideas anyone?? Thanks!

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-ibjoe
now: '73 LT; '79 Z28
then: '67 coupe; '88 IROC; '95 Z28

RickD · Jul 26, 2001

I suspect the problem is steel on steel. On my Holley, I needed a large, thin washer to seal the inlet. This was where the large ( 1"?) fitting screwed into the carb body. Any speed shop has them. Perhaps this is what the Q-jet needs.

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Rick Dorion
69 RS Conv,355,M20,4.10's

Winch · Jul 26, 2001

I was getting this too. I wrapped several layers of plumber's teflon tape on the fitting and tightened it good. Problem went away.

Dobek · Jul 26, 2001

Careful with the teflon tape - I agree it works - but as you thread together - the teflon tape splinters and runs into the carb - depending upon where it ends up, it could cause a blockage.

Happened to me - I had fuel pouring out of my idle vent.

Steve

Stewie · Jul 26, 2001

Are you sure it is the fitting that is leaking. I recently had a leak at the rear inlet to my Holley 4053 DZ I had to replace the float bowl. The housing was stripped. With all the bending of the line I still have a "sweat leak" I tried the teflon and I now have to order a new fuel line. The fitting has rounded off a little and I don't think it is square to the inlet on the flare at the end of the line. I can't get it to seal.
I think the bending of the line has something to do with the leak in your case.

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Only 69 Z/28s
Garnet Red 30,000 mi
Glacier Blue
Rally Green new in 69

ibjoe · Jul 27, 2001

Hey, I got it fixed, status report:
RickD, you were right, problem was steel on steel. The old steel line just would not conform with the old steel fitting. I called around a bit. Speed shop only had "repair" units, for if the carb was stripped out. Suggested a carb shop, that was a dead end, the guy was clueless. So I called a chevy dealer, the parts man knew the part, found a # for it, but said no it is longer made. He suggested a place, Speedometer Electric, turns out they also do carbs. The fellow there got me a new fitting. Brass, not steel. It looks a bit different, but functionally identical. I popped that puppy on, followed his suggestion to put some grease on the threads and flare (to prevent galling). Only problem was the new unit was a bit deeper, the fuel filter needed to be about 1/8" longer. I made up a gasket to space it out OK, no biggie. Tightened it up "reasonably" tight, not super tight, just what felt should be right. Fired it up, not a drop of leakage. Yay!

I didn't want to use teflon tape, as the flare is supposed to seal on the fitting, if fuel gets to the threads then something is wrong.

I'm so happy, the new quadrajet (which I spent 3 days rebuilding) runs perfectly!

Thanks everyone for your ideas and support!

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-ibjoe
now: '73 LT; '79 Z28
then: '67 coupe; '88 IROC; '95 Z28

fuel leak at carb, help!

ibjoe

RickD

Winch

Dobek

Stewie

ibjoe

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