Leaking carb

[ukstu]

Hi all,
I have a fuel leak from my carb. Enough to form a small pool in the top of the manifold. My initial thought is it will just be a poorly fitted gasket, however, you will no doubt know better than me.
move attsched a picture to show where it seems to be leaking from (No’s 1&2, and pooling at no3).
Can I assume this is just a bad gasket or can this be a result of something wrong inside the carb which is forcing fuel past the gasket?
advice and opinions welcomed please.

thanks

 

[Scott Danforth]

the intake will accept either pattern of carb. what you are seeing is the intake under the carb

that is not the source of your leak.

 

[ukstu]

the intake will accept either pattern of carb. what you are seeing is the intake under the carb

that is not the source of your leak.

Hi,
Yes thanks for the reply, the leak is coming from between the gasket between the intake and the carb. I suppose I was wondering if this could just be a bad gasket or whether the is a leak internal in the carb. Is there anyway of testing the carb now I have it off to see if fuel is escaping? Or just a case of replacing the gasket to see if that stops it.

 

[ukstu]

Previously when I’ve stripped and cleaned carbs I’ve had access to an ultrasonic cleaner.
unfortunately this time I do not, what is the best way without one?
I’m thinking a stiff (non ebrasive) brush and some carb cleaner, maybe soak the parts in some carb cleaner?
many advice or opinions?
thanks

 

[Lou C]

On the Quadrajet there are 2 main gaskets, one is between the throttle body and main body the other is between the main body and air horn, but a leak like that is more likely due to a leaking needle valve that is not shutting off the fuel flow when the bowl is full, causing a leak. I'd replace the needle valve and seat for sure. I have done mine by just using carb cleaner (wear goggles) and a good air compressor (not canned air, but a real compressor, a little hot dog compressor will do. You can get good quality marine rebuild kits from Cliff's High Performance Quadrajets....
make sure to change the accelerator pump as well, they can cause leaks as well, because some do not hold up well to modern gas with ethanol.

 

[ukstu]

On the Quadrajet there are 2 main gaskets, one is between the throttle body and main body the other is between the main body and air horn, but a leak like that is more likely due to a leaking needle valve that is not shutting off the fuel flow when the bowl is full, causing a leak. I'd replace the needle valve and seat for sure. I have done mine by just using carb cleaner (wear goggles) and a good air compressor (not canned air, but a real compressor, a little hot dog compressor will do. You can get good quality marine rebuild kits from Cliff's High Performance Quadrajets....
make sure to change the accelerator pump as well, they can cause leaks as well, because some do not hold up well to modern gas with ethanol.
View attachment 339356

Thanks Lou C for the reply, great info there. I’ve got a decent rebuild kit from a trusted local supplier so will set to it tomorrow. Useful to highlight the possible areas that may have caused the problem.
I had wondered if this may have been caused by the ethanol..

 

[Lou C]

I've had mine leak 2x over the years, I get about 6 years between rebuilds. The better kits like Cliff's might get you more time. If you've never taken apart a Q-jet there are a few tricks, namely with the accel linkage, & the choke linkage. You also have to be careful with the metering rods. However the gaskets used don't stick to the housings like on Holleys....There are some good vids on those 3 points on You Tube.....

Quadrajet Marine Rebuild Kit – Cliffs High Performance Quadrajets
Here's what I'd use....
another good source of parts.....
Carburetor Parts & Kits for Carter, Ford Motorcraft, Holley & Rochester Carburetors (quadrajetparts.com)

It's amazing they have not been built in 30 years yet you can get nearly any part if you have a good core. Properly build they are excellent carbs.

 

[ukstu]

Just an update, in case it helps someone else out in the future.
rebuilt the carb using the service kit, replaced all parts as required.
The seal on the accelerator pump was pretty slack...
Re fitted today and fired up nicely. Ram for a good while and no more leaks!
funnily enough, it had been 6 years since I last did it.
thanks all for the input.

 

[Lou C]

Yep I’m replacing my accel pump with an improved version from Cliffs High Performance Quadrajets this week. I know the one that’s in there has been a long time and just started seeping a bit last season.