We have a small leak in the carb of our 454 engined Regal. Where the fuel pipe goes into the carb is a brass fitting which itself screws into another fitting. The leak is where the tube goes into the first fitting. The fuel feed tube is new, installed two years ago. I know the tube has a flared end. The nut seems tight. Question, should I put some sealant around the threads of the brass fitting? Or does that brass fitting need no sealant of any kind? Of course, when I take it apart, I may find a crack in the flared fitting, but the question still remains about the sealant around the brass fitting.
Thanks
Jim

Boy Jim, I may be way off on this and should wait for others to chime in... but I think that's somewhat of a serious problem with these carbs. A leak like that is nothing to 'patch up' with some sealant. It needs to be addressed properly before you end up with one of those 'skeletonized' RV's we see the photos of sitting on the side of the road with the fire trucks helplessly pouring water on a smoldering mess.

Kirk

Jim, may be crossthreaded.. Brass carb fittings do not require any sealeant.. take them off and buy new fittings at a Napa store. gas leaks are a BAD thing. it can ruin your day. new fittings are cheap insurance . Brian

The inlet tube is a flare fitting, shouldn't need sealer. On mine, the inlet filter housing screws into the carb body and has a nylon gasket.

The filter housing threads are very easy to cross thread and strip, be careful!

As has been mentioned, leaks at this location should NOT be addressed with "alternative" solutions. The threads ARE NOT the source of sealing; the flare junction is.

First, replace the filter accessible after the flare fitting is removed. Then inspect the flare at the line for defects. If, after reconnecting, there is still a leak, a light film of very high quality sealer (I use Permatex Aviation Form-A-Gasket Sealant Liquid, P.N 765-1210, available at NAPA) on the tube flare is acceptable.

A light coating of grease on the fitting threads will make it easier to make the connection. NOTE!: A backup wrench on the filter hex is necessary.

If your leak is where the flare nut enters the inlet fitting/filter housing, it is possible that one of the previous mechanics used an open end wrench (or worse) instead of a flare nut wrench and distorted the nut, preventing uniform pressure on the flare.

Those poor things often take a beating.

Sometimes the line nut can be squeezed to its original shape and a good seal can result. Careful work with a countersink can sometimes restore the seating surface of the flare to concentricity.

If it can't be saved, the entire line can be replaced, but that is no fun. The end can be cut off at a straight section and a new end cut from a universal fuel line can be spliced in with a compression splice. A fuel hose can work, but only for dire emergencies. That location is too hot for a hose over any time.

It is also possible that the seat inside the filter housing is damaged, and the housing would need replacing. Be sure to use a new gasket if you do that.

There are two different types and sizes of fuel filter housings, so be sure to get the right one and gasket.

I'm afraid I have to take responsibility for using an open end wrench .(presume this means embarrassment). I don't want to take it apart until I don't have to move it. Spray foam guy is coming tomorrow to spray the roof of the garage so will have to move Barth then. When he is finished, I'll put Barth back inside and take things apart. No telling how long this has been leaking. We may have been very fortunate that a fire has not started. Where do you get a 'flare nut wrench'?
Jim

Flare nut wrench sets are available at any home improvement, auto parts, hardware stores and Harbor Freight.

When my son-in-law built his 69 Camaro, he replaced the solid line to the carb with A/N fittings and rubber hoses with heat shields. His carb is a Holly and he's not sure if there are A/N fittings available for a quadrajet. Even if there are, some comments please?

A properly cared-for stock set up is fine. One of it's virtues is that it gets less heat by being in front of the engine. This helps avoid vapor lock.

AN looks trick and is handier if you break the connection often.

BTW, a low-quality Chinese flare nut wrench is likely to do almost as much damage as an open end or Crescent wrench.

Jim, can you take a picture of your fitting set up. The factory set up should be steel lines with inverted flare going into the fuel filter housing. Brass fitting and flare nuts sounds like its been modified.

My filter housing is steel.

AN fittings are standard, but it's fitting to fitting, and the tubing is not part of the fitting. Typically, an AN fitting is swaged onto the tubing.

NAPA has the correct shielded hoses.

Finished the spray foam job on the garage and put Old Blue back in. I had loosened the fitting around the fuel pipe and then re-tightened it but that did not help. Took everything apart. The fuel deliver pipe and flare does not appear to have any cracks in it. I examined with a magnifying glass. The fitting that the pipe goes into does not seem to have been abused. Although I did notice that it was not very tight where it screws into the carb. The nut on the fuel pipe that compresses the flare also seemed ok. I did see some small deposits that almost looked like sand when I took everything apart. So I guess I'll clean everything up, maybe lightly sand the flare on the pipe, and put everything back together. Any suggestions?
Jim

quote:

Originally posted by Jim and Tere:
So I guess I'll clean everything up, maybe lightly sand the flare on the pipe, and put everything back together. Any suggestions?
Jim

A little Prussian blue might tell you what is making contact and what is not.

Lapping the interface with valve lapping compound might make better sealing surfaces.

There are thin, soft aluminum cupped washers that fit on the nose of an AN fitting to stop a stubborn leak. I have never tried one on a Qjet, but they work fine on airplanes.