Fuel Filter THread

[kmam]

I am having some problems (again) which seem to be caused by crud getting into the carbie from the fuel line. I intend replacing the metal cased filter that screws into the carbie with a connection for a rubber fuel line and then running a common in line filter. I need to fit a male thread to tag to connect the fuel line and can either fit it in place of the existing filter or fit it directly to the carbie. I am not sure what thread the carbie and filter are so I can find a suitable part. Can someone please tell me and also if either of them is tapered?

[Mark]

The thread is straight in the hole for carburetor inlet, I think it is 1/8"--27 NPT so OJT might be required with a nipple.My terminology might need to be corrected

[rickf]

The threads in the carburetor are straight thread and NOT tapered pipe thread. This is why there was a special fitting on the carb originally that had straight threads and a flat brass nut with a nylon sealing washer on the carburetor side and female 1/8" pipe thread on the other side for the filter to thread into. What happens is a lot of people just thread the filter directly into the carb since the thread count is the same and it will thread in, the problem is that the filter is tapered pipe thread and now it is enlarging the hole in the inlet of the carburetor. I have seen many times where this splits the top of the carburetor, especially on the old Holley carbs. Once the filter is screwed into the carb body and if it is screwed in tightly then the original fitting is probably no longer going to work. If you keep trying to put new filters in there eventually the carb will break or it will start leaking at that point. You can get a male hose barb fitting that has 1/8" pipe thread and put it in the carb but do not use teflon tape as that will lubricate it and probably cause it to tighten to tight and break the carb. What I did on mine,I still have the original fitting and filter, is I took the original filter and drilled out the insides of it so it is straight through and then reinstalled it. This way it still looks original and I added the inline filter in the inlet line. If you are running an A2 be sure to put your inline filter somewhere away from the exhaust manifold, Most people mount them right before the carb which is right on top of the exhaust manifold and then they wonder why they have vapor lock. While I prefer to have the filter after the pump on an A2 everywhere after the pump is near a heat source. At the pump outlet you have the lower radiator hose and higher up you are right in the hot air from the radiator and then you have the exhaust manifold. If you prefer to have it after the pump then close to the lower radiator hose is the best option.

[kmam]

Great info, thanks to both posters. I like your suggestions Rick and will go down that path...