1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

[Carlos Z.]

Hello everyone, I am relatively new to the Vette ownership world, therefore new to NCRS. About four months ago I was able to purchase the car I had dreamed of since I was a child, a C3 Stingray (1974 CORVETTE 454 Manual Trans), which I absolutely love and enjoy.

Last week after a relatively short drive I noticed a really strong gas smell in my garage. I removed the carburetor filter housing and found gas on every corner of the top of the engine. The amount of gas was such that I was really fortunate it didn't set the car on fire.

After long days researching and attempting to figure out the location of the leak, I noticed an aluminum plug (next to the fuel filter housing) that is covered with what appears to be black epoxy, and happens to be pealing off. Looks like that's where gas found its way out.

Again, being new to this I am unaware about my options and would very much appreciate some help. Is the plug repairable? Alternatively, would the carburetor need to be unassembled and shipped to be restored? If so, would anyone happen to know of a reputable person/place to use?

I looked online and found one that matches the exact numbers, going for $1,350. The car has been very well cared for, and it's mostly original, so I would hope I can keep it as such, understanding all the disadvantages of a Q-Jet..

Thanks again for the assistance, I really need it.

Carlos

[Jimmy P.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

Hi Carlos,
I had this issue with my Qjet on my 73 a few years back in the same location you are describing. However, my leak wasn’t as bad as yours seems to be. I did try the epoxy repair route and tried J-B Weld as many others have recommended and had success with, but that repair didn’t last very long and it started leaking again. Instead of trying the vast array of other epoxies I just had my mechanic drill out the plug (pretty sure it’s lead) and then he tapped(threaded) it and inserted a screw in plug with locktite on the threads.That was back in 2015 and hasn’t leaked yet! I know it’s probably not an NCRS acceptable repair but it worked for me. I wouldn’t buy another carb if I were you, keep your original just have it rebuilt/repaired.
Here are a few photos…one showing a restored carb with the epoxy fix…one from my car showing the leak and one showing the repair using the threaded plug. I’m sure you’ll get other responses here as well!
Hope this helps!

[Joe L.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

Hello everyone, I am relatively new to the Vette ownership world, therefore new to NCRS. About four months ago I was able to purchase the car I had dreamed of since I was a child, a C3 Stingray (1974 CORVETTE 454 Manual Trans), which I absolutely love and enjoy.

Last week after a relatively short drive I noticed a really strong gas smell in my garage. I removed the carburetor filter housing and found gas on every corner of the top of the engine. The amount of gas was such that I was really fortunate it didn't set the car on fire.

After long days researching and attempting to figure out the location of the leak, I noticed an aluminum plug (next to the fuel filter housing) that is covered with what appears to be black epoxy, and happens to be pealing off. Looks like that's where gas found its way out.

Again, being new to this I am unaware about my options and would very much appreciate some help. Is the plug repairable? Alternatively, would the carburetor need to be unassembled and shipped to be restored? If so, would anyone happen to know of a reputable person/place to use?

I looked online and found one that matches the exact numbers, going for $1,350. The car has been very well cared for, and it's mostly original, so I would hope I can keep it as such, understanding all the disadvantages of a Q-Jet..

Thanks again for the assistance, I really need it.

Carlos

Carlos------

Fuel leakage due to a failed soft plug at the front of the inlet chamber is a common problem with Q-Jets. This can be repaired using epoxy but it cannot be repaired by simply applying epoxy over the failed plug. To do it properly, the plug has to be removed, the orifice cleaned and roughened, and the orifice filled with epoxy.

It can also be repaired by installing a threaded pipe plug as Jimmy has described. However, there is a risk to this. The carburetor float bowl (the carburetor component part with the soft plugs) is made of zinc diecast material. This material is quite soft and non-ductile. So, boring and tapping can be problematic and can result in a ruined float bowl.

[Ed D.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

Carlos,
Being that the Carb is new to you and you dont have any history with it. I would send it to Custom Rebuilt Carbs in NJ and have him rebuild and fix anything that it needs. I am sure Phil can fix that leak as well. Lots of NCRS guys use him. Custom Rebuilt Carburetors

www.customrebuiltcarbs.com
Ed

[Chris H.]

https://www.corvetteforum.com/forums/c3-tech-performance/4703199-rebuilding-joserpaq-s-1980-q-jet.html

[Jeffrey S.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

Carlos,
Contact Lars Grimsrud at v8fastcars@msn.com. he has done work for me and I think he is the best out there. He post regularly on Corvette Forum.
Jeff

[Bob I.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

Carlos,
Contact Lars Grimsrud at v8fastcars@msn.com. he has done work for me and I think he is the best out there. He post regularly on Corvette Forum.
Jeff

[Joe L.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

There are other soft plugs on a Q-Jet that can leak. However, these leak into the intake manifold and cause engine running problems or severe flooding. I know of no way other than epoxy to repair these although there may exist such a way now.

The photos below are of an NOS GM #7036558 float bowl assembly [not for sale]. This assembly is applicable to 1969 Corvette and passenger car with 300/350 and manual transmission (like my car). Note the two small and 2 larger soft plugs on the bottom of the float bowl.


DSCN4144.jpgDSCN4145.jpgDSCN4146.jpg

[Carlos Z.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

All, THANK YOU infinitely for the prompt and helpful replies. I'm relieved that these aren't uncommon issues as there seem to be multiple alternatives to get my baby back on the road. I will evaluate the best long term solution as I plan to keep the Vette until God decides to take me Very much appreciated.

[Owen L.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

This can be repaired using epoxy but it cannot be repaired by simply applying epoxy over the failed plug. To do it properly, the plug has to be removed, the orifice cleaned and roughened, and the orifice filled with epoxy.

It can also be repaired by installing a threaded pipe plug as Jimmy has described. However, there is a risk to this. The carburetor float bowl (the carburetor component part with the soft plugs) is made of zinc diecast material. This material is quite soft and non-ductile. So, boring and tapping can be problematic and can result in a ruined float bowl.

As a stained glass artist, I'm thinking it could be properly repaired with 50/50 lead solder as well. After cleaning and removing a bit of the surface of the existing plug with a burr, adding flux, and dripping in melted solder, the plug should be well-sealed to the die-cast zinc.

Sound feasible or foolish?

[Joe L.]

Re: 1974 454 Q-Jet 7044221-DX | Need Help With Fuel Leak!!

As a stained glass artist, I'm thinking it could be properly repaired with 50/50 lead solder as well. After cleaning and removing a bit of the surface of the existing plug with a burr, adding flux, and dripping in melted solder, the plug should be well-sealed to the die-cast zinc.

Sound feasible or foolish?

Owen------


That might work. I've also thought about the use of the low temperature rod available from Muggyweld but I've never tried it for the application. I know that it does work on zinc diecast, though (as well as most other metals).