What fuel pump is on the engine? Quadrajets don't like more than about 3psi of fuel pressure, from what I've read.
Quadrajet intake gasket is wet, erratic high idle.
- Thread starter MrSony
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15/32 as per the manual that came with the kit. I get all my stuff from quadrajetparts.com, never had a problem. I've checked the air horn and the main body, top and bottom, and the throttle plate for warpage with a machinist's straight edge, and it is not warped. I put the air horn on the main body, sans screws, and there was no rocking movement at all. It sat flush. It was really cruddy on the inside, it sat for a few years is my understanding, but I didn't see or notice any hairline cracks or anything. I filled the bowl with gas and let the main body sit overnight on a piece of paper with ink on it, and the paper was dry as a bone and the ink was not smudged one bit. But it's still leaking somewhere. I did use an oddly thick base gasket, but when I used the thin one that one was wet as well.
It's just a stock, or stock replacement fuel pump. The engine I'm testing it on came with a qjet from the factory and currentlly runs just fine with it. But when I swap mine on it sounds like crap. Is it because my qjet is for a 350, and I'm testing it on a 305? It's the only working SBC I can get my hands on for testing purposes.
Basically there are only 2 q jets - 800 - 750 . even on the v6. There are just configured different for each app. Concept is all the same. If they are tuned right they will run on anything. So the carb should work on both a 350 and 305. BTW Chevy only used 750s. Even on BBC.
What are the needles and jets numbers? Did the ends get broken off? If one carb runs and the other "sound like crap" some thing is wrong wit the carb. you don't need another test engine. Can you look in the carb while it is running and see fuel dripping? If so likely needle and or float.
Check the needle and seat for crude in it, maybe clean the carb again. An emissions 350 carb will run fine on a 305, just slightly rich on a stock 305.
Maybe mismatching parts? There is a Qjet expert named Lars on the Corvette forums who has a few threads on bizarre problems he has fixed for other members. One case was a Qjet that had mismatched airhorn to main body. Basically Qjet either have air bleeds in either the airhorn or main body, but they cannot have both which is why the airhorn needs to be matched with the airhorn. Other than cracks, castings can also develop porosity which is very hard to detect. Was the Qjet ever remanufactured? Many times they do weird stuff to Qjets that are not easy to detect. Never use brass floats in a Qjet, they just do not work right.
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No leaking at all, until it is put on the engine. I did not epoxy the plugs, I just replaced them. I bought some of that marine tex... whatever epoxy and slathered it on the new secondary plugs and primary plugs. I'll test it later today (monday) and see if that made a difference. I also got a thicker air horn gasket in it.
As far as I know, the carb was 100% original, or at least retained all it's original parts, except the choke pull off. It works, and the guy doesn't care about originality so I left it on there. I ran out of epoxy before my testing opportunity came (it's my brothers SBC in his truck, he needed to use to to help move today, other than that it just sits being as he is only 15) and I suspect the plugs were dribbling causing the issues. I got some epoxy last night and coated the plugs. Later today (monday) I have another testing oportunity with the truck and I'll see if it's any better. The carb didn't look beat up or abused at all really, just an old carb that sat for a few years and had some crud in it. I've done worse with better success, for the guys sake I hope this one is saveable in my hands. I mean it runs and idles fine, just can't get it to not idle any lower than 1400. And stupid sbcs... you can't get to anything on the carb on these engines. I miss my buick. everything was out in the open.
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