carburetor PROBLEM HELP! on 77 CORVETTE!
12-13-2006, 10:38 AM
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Most people on this board do not use carbs, but some more info would help. Is it a qjet or holley? mechanical or vacuum secondaries? I would suggest first cheching the linkage for binding. after that look at the diaphram if it is vacuum secondaries.
12-13-2006, 07:57 PM
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qjet i think is what i got. and the vacuum or mechianel i dont know but everything else is vacuum on the car the front lights. So i would go with a vacuum. And im located in CA San Lorenzo 94580.
12-14-2006, 10:55 AM
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how do you know the secondaries are not working? if you crack the throttle with the car running while looking at the carb they most likely will not open unless you rev it for a long time. the flaps that you see with the air cleaner off is the air valve, the actual butterflies are below them. the car has to be fully warmed up for them to work, on a 77 i think the choke is electric if the choke coil is bad it will not pull the choke off far enough to unlock the lower butterflies. or the diaphram could be bad or stickey linkage as mentioned before.
mitch
mitch
12-14-2006, 02:09 PM
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Well i had my uncle in the car and i was watching the carb the secondarys wouldnt open at all untill my uncles friends opened in manuely. I can see the butterflys because i looked down into the carb. Ill
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12-14-2006, 03:18 PM
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Quadra Junk I have had 3 vettes with quadra-jet 4bbl carbs. In the 70's, they were nick named the quadra-bog. 
They are just terrible. In my opinion they are not worth rebuilding. Most of them never worked properly even when new. They are a pain to adjust. 
Yours may not even have a set of air idle screws just under the front bottom of the carb. I believe Holly makes a direct bolt on replacement for the q-jet. It's the one with small primary butterflies in front, and very large rear butterflies. It would be worth your time and money and frustration to buy the replacement. 
Also, check with Edelbrock, they may have a unit for direct bolt on replacement. If your intention is to keep the car box stock, you should find someone qualified to rebuild the carb. I am pretty good with the old units, but I have never successfully rebuilt one. They are complicated, and finicky. All of the other responses I read are correct. Check the choke, check your vacuum lines, check the vacuum dashpot on the side of the carb itself. Those usually go bad because they were made form rubber and just become brittle with age. Now that I have said all of that, how is it running? You should be able to feel a gradual increase in power as the secondaries open. If the car is fully warmed up, and they are operating properly the top butterflies will crack open slightly when the throttle is fully opened. You should be able to see them open with the air breather off, and you cracking the throttle using the linkage. Also, do yourself a favor and stay away from any replacement with mechanical secondaries. They are gas guzzlers, and will have a high propensity to bog when you stand on the throttle. They also make your plug life very short, due to fuel fouling. Hope this gets you pointed the right way. Mike Fesi
They are just terrible. In my opinion they are not worth rebuilding. Most of them never worked properly even when new. They are a pain to adjust. Yours may not even have a set of air idle screws just under the front bottom of the carb. I believe Holly makes a direct bolt on replacement for the q-jet. It's the one with small primary butterflies in front, and very large rear butterflies. It would be worth your time and money and frustration to buy the replacement. Also, check with Edelbrock, they may have a unit for direct bolt on replacement. If your intention is to keep the car box stock, you should find someone qualified to rebuild the carb. I am pretty good with the old units, but I have never successfully rebuilt one. They are complicated, and finicky. All of the other responses I read are correct. Check the choke, check your vacuum lines, check the vacuum dashpot on the side of the carb itself. Those usually go bad because they were made form rubber and just become brittle with age. Now that I have said all of that, how is it running? You should be able to feel a gradual increase in power as the secondaries open. If the car is fully warmed up, and they are operating properly the top butterflies will crack open slightly when the throttle is fully opened. You should be able to see them open with the air breather off, and you cracking the throttle using the linkage. Also, do yourself a favor and stay away from any replacement with mechanical secondaries. They are gas guzzlers, and will have a high propensity to bog when you stand on the throttle. They also make your plug life very short, due to fuel fouling. Hope this gets you pointed the right way. Mike Fesi 
12-15-2006, 05:34 PM
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NO the new smog law stats that cars from 1976 and under dont need smog everything else does... And the vette will be my daily driver but i want power too so yea u get it well thanks illl talk over wit my uncle on maybe upgrading to a newer and better carb!Any ideas on carb please well free to inform me!
670, 77, adjust, arent, carb, carburator, carburetor, corvette, mechanicallinkage, opening, operate, rebuild, secondaries, simi, stock
