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I’m an amateur, but I’ve rebuilt several carbs. Simple stuff. The one item which makes this job tremendously more easy is to build yourself a small carb stand out of 2”x4”. The holes you see are where I screw the carb into the wood.
11.5” x 7.5” if a Q-Jet
Last edited by Vintage Chief; August 22nd, 2020 at 08:12 AM.
I’m an amateur, but I’ve rebuilt several carbs. Simple stuff. The one item which makes this job tremendously more easy is to build yourself a small carb stand out of 2”x4”. The holes you see are where I screw the carb into the wood.
11.5” x 7.5” if a Q-Jet
Yeah I usually use my drain pan and some Oldiies
Last edited by JOHNNYOLDS442; August 22nd, 2020 at 08:22 AM.
Left to right
7029251 7040253 7027157
69 ,70, 67 All three different chokes but can I take the 67 top and put it on the 70 because the secondary plate screws are stripped on the 70?
Your fuel pump could be a very good place to inspect. My '68 leaked fuel out the top of the accelerator pump. I never checked the fuel pump because I thought it either worked or didn't work and it was working. Finally checked it and found out it was sending nearly 10 pounds of pressure to the carburetor...way too high for a quadrajet. I understand a quadrajet is supposed to run about 5-6 pounds and the absolute max is around 7.5 pounds. I changed to a new fuel pump and, after over seven years of misery and rebuilding the carburetor 3 times, the new fuel pump made all the difference in the world! Car has run great (with no fuel leakage) since the fuel pump change-out.
Your fuel pump could be a very good place to inspect. My '68 leaked fuel out the top of the accelerator pump. I never checked the fuel pump because I thought it either worked or didn't work and it was working. Finally checked it and found out it was sending nearly 10 pounds of pressure to the carburetor...way too high for a quadrajet. I understand a quadrajet is supposed to run about 5-6 pounds and the absolute max is around 7.5 pounds. I changed to a new fuel pump and, after over seven years of misery and rebuilding the carburetor 3 times, the new fuel pump made all the difference in the world! Car has run great (with no fuel leakage) since the fuel pump change-out.
Randy C.
thanks Randy how do I check fuel pressure
or do I just get a new one?
maybe when this guy did the motor he bought a high pressure fuel pump it looks stock put you cannot tell pressure by looking at it.
I have a mechanic friend who had the equipment to check the fuel pressure with an in-line pressure gauge between the pump and the carburetor. I forgot to add that fuel was leaking out of the top of the accelerator pump at idle. The fuel pump I had was a replacement stock-type unit and it worked well for awhile but, somewhere along the line, it went bad. I don't know if the return line got clogged and it resulted in delivering more pressure to the pump-to-carb line or what. But after I found out the pressure that was being delivered to the carburetor, I bought another replacement fuel pump and installed it myself. The car has run great since then.
I'd find someone that can check the fuel pressure for you first before buying a new pump, just to be sure you aren't wasting money on a new pump. As well, I do have an extra fuel pump I can send to you if you are headed in that direction.
I have a mechanic friend who had the equipment to check the fuel pressure with an in-line pressure gauge between the pump and the carburetor. I forgot to add that fuel was leaking out of the top of the accelerator pump at idle. The fuel pump I had was a replacement stock-type unit and it worked well for awhile but, somewhere along the line, it went bad. I don't know if the return line got clogged and it resulted in delivering more pressure to the pump-to-carb line or what. But after I found out the pressure that was being delivered to the carburetor, I bought another replacement fuel pump and installed it myself. The car has run great since then.
I'd find someone that can check the fuel pressure for you first before buying a new pump, just to be sure you aren't wasting money on a new pump. As well, I do have an extra fuel pump I can send to you if you are headed in that direction.
Randy C.
I ordered a new Carter fuel pump should be here in a day or so.
when i take the fuel line off after a test run the pressure seems very high as it squirts big time, you may have somthing thing there. i will report back. Thanks!
I ordered a new Carter fuel pump should be here in a day or so.
when i take the fuel line off after a test run the pressure seems very high as it squirts big time, you may have something thing there. i will report back. Thanks!
Replace Rochester pump assembly. Get a good one to replace. Also check the wall. Today's fuel with ethanol eats up the old ones. Or just old.
The Q-jet is a great carburetor and in my opinion the best to maintain good drivability. I suggest you get a copy of the Cliff Ruggles book on Q-jets or the Doug Roe book, Rochester Carburetors. Unleaded gas is supposedly harder on the throttle shaft bearing surfaces and they are known to wear out on older carburetors anyway causing idle issues; thus the repair kits that are readily available. The top plate or air horn may be warped excessively from repeated rebuilds and need straitening.
Lithium Grease the Airhorn Gasket - if you change jet/rods often
I find that a light coat of lithium grease on both sides of the air horn gasket makes it last a few jet changes without the gasket sticking to the main body or air horn.
Polish your Power Piston
I also lightly polish the outside of the power piston and the inside of the cylinder it slides in to make sure it moves up and down as easily as possible. The idea is to remove all resistance except vacuum and the spring it works against.
These are little things. I wouldn’t tear into a good qjet just do to them, but if you have it apart, they each take about 5 minutes.
August 22nd, 2020, 07:25 AM
