Q-jet questions
Thread Starter
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Q-jet questions
On a Q-jet, what would cause the fuel in the bowl to leak down into the intake while the car is parked? Can this problem be solved with a standard rebuild? Are there other issues outside of the general rebulid I should check for? This carb is on another chevy that I own. Not the vette.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Q-jet questions (Jvette73)
There are some plugs on the bottom of the bowl that tend to leak. You can peen the edges and then put a good epoxy. JB weld .. but not the quick type works good. This is a common problem with Q-jets.
Thread Starter
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Q-jet questions (silvervetteman)
Thanks silvervetteman, Ill check those plugs out. It leaks down pretty quick. Im sure its not good to have all that raw gas leakin down. Maybe even getting into the oil pan and thinning the oil. :eek:
Safety Car
Joined: Mar 2000
Posts: 4,077
Likes: 27
From: Northeast South Dakota
Re: Q-jet questions (Jvette73)
Sounds like the fuel well plugs to me. I used to have a pic of them to post, but must have deleted it. Hopefully somebody will post the pic again. It seems to me that Ki M Le posted the pics once a while back.
Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Q-jet questions (Jvette73)
You can check out the fuel well plugs pretty easily: Pull the carb off and fill the bowl with fuel (through the vent tube). If the plugs are leaking, they're visible from the bottom of the carb, and you can see the fuel dripping from them.
If fuel is dripping from the two (or one of the two) primary wells, coating them with epoxy or JB weld is not a very good way to go: this type of repair will not last very long before it starts leaking again. I've been drilling the plugs out and tapping the plugged holes for a #10-32 thread. I then take an allen-head countersunk screw, coat it with epoxy, and screw this into the tapped holes. This will positively and permanently seal the primary wells.
If fuel is dripping from the two (or one of the two) primary wells, coating them with epoxy or JB weld is not a very good way to go: this type of repair will not last very long before it starts leaking again. I've been drilling the plugs out and tapping the plugged holes for a #10-32 thread. I then take an allen-head countersunk screw, coat it with epoxy, and screw this into the tapped holes. This will positively and permanently seal the primary wells.
Thread Starter
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Q-jet questions (Jvette73)
Thanks for the info lars, I thought I had heard of this fix before on here. When I do get around to it, it will be nice to have it fixed permanently. What brand and what type epoxy is good.
Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Q-jet questions (Jvette73)
Jvette -
If you heard of this fix here before, it was probably one of my earlier postings... This technique was developed by Ken Crocie of H-O Racing Specialties (Hawthorne, CA), and I was one of his dealers. Since they went out of business, I have duplicated their technique, which is the best, and only permanent, well-plugging technique I have ever seen.
The countersunk screws are the "plugging medium", and the epoxy only acts as a final sealant with this technique. You can buy any of the Devcon brand epoxies at a hardware store, but avoid the quick-drying "5-minute" epoxies as they tend to get brittle. Just a light coat of epoxy on the screw threads before you screw the plugs in, and it will seal up tighter than a....... eh..... I can't use that term here - it's a family forum... but you get the idea.
If you heard of this fix here before, it was probably one of my earlier postings... This technique was developed by Ken Crocie of H-O Racing Specialties (Hawthorne, CA), and I was one of his dealers. Since they went out of business, I have duplicated their technique, which is the best, and only permanent, well-plugging technique I have ever seen.
The countersunk screws are the "plugging medium", and the epoxy only acts as a final sealant with this technique. You can buy any of the Devcon brand epoxies at a hardware store, but avoid the quick-drying "5-minute" epoxies as they tend to get brittle. Just a light coat of epoxy on the screw threads before you screw the plugs in, and it will seal up tighter than a....... eh..... I can't use that term here - it's a family forum... but you get the idea.
Thread Starter
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Q-jet questions (lars)
Thanks again lars. I know I can trust Q-jet advice from you. Youre a great help to me and all the other members. On to the carb issue. I removed the carb and took the top off. The larger two of the 4 air bleeder tubes,(i think thats what thier called), were dislodged from the airhorn and were laying down in the resivoir. Whats the trick to getting these things to stay in place?
Also I filled the bowl with gas to check for leaking plugs in the bottom and found no leak there. The carb is very dirty and wet on the outside though. It looks as though gas could have been seeping out the gasket in between the throttle body and baseplate. The plenum area inside the intake is as spotless as it was new. Im gonna soak all the parts in a bucket overnight. I wanna get this thing spotless clean. What type of cleaner should I put in the bucket? Will mineral spirits work?
I havnt touched the idle mixture screws and never have as long as I have owned it. Would it be best just to leave those alone?
Also I filled the bowl with gas to check for leaking plugs in the bottom and found no leak there. The carb is very dirty and wet on the outside though. It looks as though gas could have been seeping out the gasket in between the throttle body and baseplate. The plenum area inside the intake is as spotless as it was new. Im gonna soak all the parts in a bucket overnight. I wanna get this thing spotless clean. What type of cleaner should I put in the bucket? Will mineral spirits work?
I havnt touched the idle mixture screws and never have as long as I have owned it. Would it be best just to leave those alone?
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