Quadrajet hot start question
Thread Starter
Registered User
Joined: Jan 2018
Posts: 100
From: 56425
Quadrajet hot start question
Ok guys, here's my situation.
i have a 72 cutlass with a 455 and stock Q jet. I have a lot of years of Q jet experience, having rebuilt and tuned many of them. I'm a big fan of the carb and enjoy getting them to run great.
I have the hot hot start issue with this unit. Between 10-60 minutes of sitting hot, it won't pop off, I have to give it part throttle and crank it to start it. If it sits Longer than that it starts fine.
ive checked for leaking well plugs and they are good. I let it sit on the bench for days with no leaks. I've tried a phenolic spacer with no improvement. I've rebuilt it, I've lowered the float level, I've tried everything that I know to try and I can't even get this issue to change.
Im starting to wonder if I'm looking in the wrong direction for an answer. Looking for ideas to try to correct this issue.
i have a 72 cutlass with a 455 and stock Q jet. I have a lot of years of Q jet experience, having rebuilt and tuned many of them. I'm a big fan of the carb and enjoy getting them to run great.
I have the hot hot start issue with this unit. Between 10-60 minutes of sitting hot, it won't pop off, I have to give it part throttle and crank it to start it. If it sits Longer than that it starts fine.
ive checked for leaking well plugs and they are good. I let it sit on the bench for days with no leaks. I've tried a phenolic spacer with no improvement. I've rebuilt it, I've lowered the float level, I've tried everything that I know to try and I can't even get this issue to change.
Im starting to wonder if I'm looking in the wrong direction for an answer. Looking for ideas to try to correct this issue.
Registered User
Joined: Nov 2015
Posts: 685
From: So. Ca.
Just for the heck of it, next time you shut down hot, remove the complete air cleaner assembly, then wait for the 10-60 minute window and do a normal restart. I don't know if this will work, but if it does the carb may be fine. The trouble could be vapor buildup, heat in the lines, maybe a fuel pump with a return line would help. Don't know the answer but the ethanol added fuel could be the culprit. Good luck.
Thread Starter
Registered User
Joined: Jan 2018
Posts: 100
From: 56425
My car does have a return fuel line and I've checked to make sure it isn't plugged. I also have tried adjusting the choke to several different settings.
I might try try the idea of removing the air cleaner cover and leave the hood open next time to allow heat to dissipate and see if that changes anything.
I might try try the idea of removing the air cleaner cover and leave the hood open next time to allow heat to dissipate and see if that changes anything.
Registered User
Joined: Feb 2013
Posts: 15,394
From: Phoenix, AZ
That is a good suggestion. It made me remember that when I installed the electric choke on my carb many years ago I had a hard time getting it set to work well at both hot and cold temperatures, so I set it to a compromise position. Could very well be what's up with my car and it's been so long I forgot about those initial problems.
Registered User
Joined: May 2014
Posts: 13
From: Valentine, Ne
I chased a problem like this with a quadrajet for weeks. I checked it several times by putting gas in the bowl and looking for leaks and could never find anything. The problem was I wasn't putting enough gas in the bowl. One day I was pressure checking the needle seat to see what pressure it released at and all of a sudden I had gas everywhere. It turned out I had a pin hole leak in one of the venturi walls that was high enough that it didn't show up till the bowl was full. A lot of gas can come out of a pinhole leak I found out.
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rhodyrocket2
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Jun 6, 2012 02:37 PM
