Carb Questions.
Thread Starter
Racer
Joined: Jul 2004
Posts: 400
Likes: 1
From: California
Carb Questions.
how hard is it to take a Quadra-junk off? and how hard is it to run a custom rubber fuel hose to the pump? im gonna have my carb rebuilt soon so i can stop sucking in extra vacuum i DONT need 
Is it possible that extra vacuum could cause a lean condition to make my vette run hot? because i put a new 4-core radiator in and even on a cool day it still wants to try to hit 220.
Is it possible that extra vacuum could cause a lean condition to make my vette run hot? because i put a new 4-core radiator in and even on a cool day it still wants to try to hit 220.
Intermediate
Joined: Jan 2005
Posts: 35
Likes: 0
From: Las Vegas Nevada
Here is some good info that might come in handy..
http://www.geocities.com/gtopercy/Pi...rajetTech.html
http://www.geocities.com/gtopercy/Pi...rajetTech.html
Burning Brakes
Joined: Apr 2003
Posts: 844
Likes: 0
From: Central KY
I don't know that the carb is contributing to your run-hot issue. I would check the timing first. Too advanced or retarded can casue hot running. If you know that the radiator is good - and with a new 4-core you obviously do, then you might have some blockage in the engine block preventing coolant flow... Some other easy things to check: be sure the radiator cap is the proper pressure rating and that it works. Check/replace the thermostat as well.
All this said, you don't want vacuum leaks! Easy enough to isolate and remedy those. For the fuel line, I would recommend you use a metal line with a short section of rubber hose from the fuel supply line at the frame to where it connects to the fuel pump.
All this said, you don't want vacuum leaks! Easy enough to isolate and remedy those. For the fuel line, I would recommend you use a metal line with a short section of rubber hose from the fuel supply line at the frame to where it connects to the fuel pump.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
EVIL -
The carb comes off with 4 bolts - nothing to it.
I would suggest you not run a rubber fuel line from the pump. Rubber lines on the pressure side of a fuel system is a bad idea, and you're asking for trouble. Ever seen a Vette burn...? There's a very good reason why GM installed steel lines. Use a steel line. They're readily available, or you can fabricate your own. Use steel.
You won't solve vacuum leaks by rebuilding the carb: the carb itself will not leak vacuum unless the entire throttle plate is actually loose.
Vacuum leaks won't cause the engine to run hot. The leaks would have to be so severe in order to cause a significant change in air/fuel mixture that the car would not idle or run. Most overheat problems are caused by an incorrect ignition timing curve and setup. Verify that your vacuum advance control unit is functional, hooked up, and in correct condition, and make sure your total timing is set up for 36 degrees and that your centrifugal advance is working. This is the biggest contributor to overheat problems.
The carb comes off with 4 bolts - nothing to it.
I would suggest you not run a rubber fuel line from the pump. Rubber lines on the pressure side of a fuel system is a bad idea, and you're asking for trouble. Ever seen a Vette burn...? There's a very good reason why GM installed steel lines. Use a steel line. They're readily available, or you can fabricate your own. Use steel.
You won't solve vacuum leaks by rebuilding the carb: the carb itself will not leak vacuum unless the entire throttle plate is actually loose.
Vacuum leaks won't cause the engine to run hot. The leaks would have to be so severe in order to cause a significant change in air/fuel mixture that the car would not idle or run. Most overheat problems are caused by an incorrect ignition timing curve and setup. Verify that your vacuum advance control unit is functional, hooked up, and in correct condition, and make sure your total timing is set up for 36 degrees and that your centrifugal advance is working. This is the biggest contributor to overheat problems.
Le Mans Master
Joined: Mar 2002
Posts: 7,456
Likes: 2
From: Coming home from Luckenbach Texas
All the Corvette vendors sell the steel line that runs from the pump to the carb. And it ain't particularly expensive.
Have you pulled your spark plugs to inspect for lean condition? Are you familiar with what the various colorations of the electrodes signify?
Have you pulled your spark plugs to inspect for lean condition? Are you familiar with what the various colorations of the electrodes signify?
Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
with Lars. Also no reason to replace the Quadrajet on a mostly stock motor. Great carb that can deliver both performance and mileage if tuned right. Problems usually result from people trying to apply Holley tuning tips to a Q-Jet.
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Race Director
Joined: Oct 2002
Posts: 12,065
Likes: 2
From: Smalltownville Michigan
Cruise-In 5, 6 & 10 Veteran
St. Jude Donor '09
Originally Posted by SteveG75
with Lars. Also no reason to replace the Quadrajet on a mostly stock motor. Great carb that can deliver both performance and mileage if tuned right. Problems usually result from people trying to apply Holley tuning tips to a Q-Jet.
Qjets are really a good reliable unit!
Thread Starter
Racer
Joined: Jul 2004
Posts: 400
Likes: 1
From: California
Thanks for all the input guys! 
i really appreciate it, and thanks for the advice Lars on the Steel line, i woulda had a medium rare corvette right about now if i hadnt read your words of wisdom. 
how would i go about checking my vacuum advance unit? is it better to just replace it because it looks really worn out but looks are deceving*sp* or would it be better to take it to a corvette shop and just have then dial it in properly? Any and All suggestions and advice are welcome.
i really appreciate it, and thanks for the advice Lars on the Steel line, i woulda had a medium rare corvette right about now if i hadnt read your words of wisdom. how would i go about checking my vacuum advance unit? is it better to just replace it because it looks really worn out but looks are deceving*sp* or would it be better to take it to a corvette shop and just have then dial it in properly? Any and All suggestions and advice are welcome.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by EVIL_GRIM
how would i go about checking my vacuum advance unit? is it better to just replace it because it looks really worn out but looks are deceving*sp* .