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Topic Review (Newest First)
09-13-2012 06:32 AM
cdminter59
Quadrajet carb rebuild

Here is a company you can send your carburetor to have rebuilt. Check them out. SMI Carburetor Other Services Rebuilding & Modifying Rochester Quadrajet Stage 1 Quadrajet Modifications SMI- Sean Murphy Induction
09-12-2012 11:51 PM
Choctaw Bob
Quote:
Originally Posted by gsoleski View Post
So if I take it apart what would I be looking for? Just cleaning the needle/seat or replacing that? Also the float? i'm guessing a brass one would be best
I'll put my two cents in. I've rebuilt maybe a thousand or so of these in my shop back in the 70's when they were very common.

First the, the photo shows the choke straight up when it's warm so that can't be the problem. These things were notorious for having internal leaks at the base of the well where the jets and rods reside. This well has 2 lead plugs in the bottom that leak in more than half of all the quadrajets I've ever seen. Lots of the rebuilders don't have any way of checking this. They just replace the carb if they leak. Some kits come with a chunk of rubber that fits between the rod and jet well bottom and the carb base.
I would first, try to get the seller to exchange the carb. If that fails, remove the screws in the bottom of the carb and carefully seperate the body and the base while leaving the carb linkage in place so you won't have to figure how it goes if you take it apart. install a rubber plug available at the auto parts store in the open space in the center of the carb and bolt the carb back together and try it. If it doesn't work, you'll have to take it apart and learn about a very complicated carb. One more tip: take it apart on a bench after first draining the bowls by turning it upside down. Then on a work bench covered by a soft towel to prevent the check balls from bouncing across the floor, take it apart.
09-12-2012 10:10 PM
RWENUTS You're jumping ahead too far!! Try the tests first.
You gotta determine the problem first and if all else fails we'll get into your carb.
09-12-2012 10:00 PM
gsoleski So if I take it apart what would I be looking for? Just cleaning the needle/seat or replacing that? Also the float? i'm guessing a brass one would be best
09-12-2012 09:49 PM
RWENUTS Yup! You might see a little fuel dripping inside. If you don't see some have someone shut the motor off for you while you look inside. If a little mist of vapour appears then you know it's flooding a bit.
Try the hose squeeze or tapping by the inlet too.
The needle/seat is what controls the amount of fuel going into the carb bowl. It sometimes doesn't take much of a piece of junk to keep the fuel from getting past the needle.
Look on that last link I gave you. You'll see the needle/seat in a pic in there.
09-12-2012 09:24 PM
gsoleski
Quote:
Originally Posted by RWENUTS View Post
You might need to pull it apart to check the float and needle/seat.
First try the look see in while running (use a small flashlight to see better). If you see fuel then tap near the inlet with the end of a big screwdriver. Sometimes that will dislodge any junk in the needle/seat.
Or while running pinch off your fuel hose with some pliers, hold it about 10 seconds then let it go. That might flush it out.
Ken's QuadraJet
Thanks i'll give this a try first. Am I looking for fuel pooling in he carb or something? I'm a little nervous about taking it apart, I couldn't even tell you what the needle and seat are for. And what could be stuck in there that could sneak past the filter? Just stuff in the gas?
09-12-2012 04:26 PM
RWENUTS Here's a pic of a choke pull off with the spring lg1969 is talking about. Your carb doesn't have this style.
Just an FYI for you.
Choke Pull-Off fits 1973 Chevy - Rochester Quadrajet Carburetor Parts
09-12-2012 04:16 PM
RWENUTS A hot fuel pump won't be a problem.
Originally you said you saw a wisp of vapour coming out by the choke plate. That indicates a high float due to something stuck in the needle/seat or possibly too much fuel pressure. After you warm up the motor leave it running and look into the carb below the choke plate. You might see a little raw fuel in there. And you might hear a slight crackle inside too. It doesn't take much flow to cause it to flood.
You might need to pull it apart to check the float and needle/seat.
First try the look see in while running (use a small flashlight to see better). If you see fuel then tap near the inlet with the end of a big screwdriver. Sometimes that will dislodge any junk in the needle/seat.
Or while running pinch off your fuel hose with some pliers, hold it about 10 seconds then let it go. That might flush it out.
Here's a link to a quad rebuild with pics. The carb there is similiar to yours except for the other pull off pot on the front.
Ken's QuadraJet
09-12-2012 03:52 PM
lg1969 The Qjet in the photo does not have the spring behind choke pull off diaphram housing, Other Q jet does have it.
Like I wrote before not all Qjet use the spring.
09-12-2012 03:12 PM
gsoleski I'm not seeing any spring that could be removed. Here are some pictures of what the carb looks like half an hour after shut off, carb and throttle are untouched. Just to see if anything is not where it should be/I don't see something obvious. Could a hot fuel pump be a problem?




09-12-2012 07:14 AM
lg1969 Hey, no big deal
09-11-2012 10:20 PM
RWENUTS Thanks!
I don't know why it would do that. I'll ponder it a bit.
Only reason I was in clarify mode was I was concerned we might confuse the OP too much.
My apoligies to the OP for jackin' his thread and apoligies to you lg for the rant.
09-11-2012 09:40 PM
lg1969 That's it! The one that sits right behind the choke pull off.
09-11-2012 09:26 PM
RWENUTS OK
You got a pic of what you're talking about.
All I can think of is the choke pull off spring.
09-11-2012 08:24 PM
lg1969 Sorry for the confusion, It's not the bi-metal I'm writing about. A while back I bought a new Q jet for a 350 69 Caprice. The minute I shut the car off and try to start it later, it would shudder and smoke at tail pipe and smell of gas. It started fine when it was cold. It had that little coil spring . I grab a needle nose and removed it. My old Q jet did not have that spring so the choke would stay open when the motor was hot. It would start up right away. A friend cross the street had the same thing his Chevy 2 barrel dual jet, and could not start it once it was hot. He also removed the spring when I told him. After that it started with no problem.
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