65 fuel filter leak

[tim colleran]

i just changed the in-line fuel filter on my 327 engine. Both sides are leaking a bit of fuel at the connecting junctions. Any thing I need to know about how to put these together?

[Joe L.]

Re: 65 fuel filter leak

Tim-----

The GF-90 fuel filter used for most 65 applications used what GM called "Dry Seal" fittings. In more standard parlance these are known as "national pipe thread" or NPT. More modern filters, beginning in 1968, used a compression fitting, but these early filters did not. So, you have to be sure that the threads are are absolutely clean and sufficiently tight. If that doesn't do it, then you may have to use a pipe thread sealer like Teflon tape.

[john38706]

Re: 65 fuel filter leak

tim, did you also replace the lines? if so the repro lines tent to leak. seems the flare quality isn't very good. i have used several repro gf-90 filters with no problems. just make sure there tight.

[Mike M.]

Re: 65 fuel filter leak

sparingly apply teflon paste and tighten fittings then wipe away excess teflon paste with old paint brush or Q-tip and judges won't detect teflon paste like they do with teflon tape. mike

[Ken Robb]

Re: 65 fuel filter leak

I have a set of "crow's foot" wrenches that are a real help in getting these fittings tight. They fit around the fitting so you don't round it off in getting it real tight. Like Mike says, I use teflon pipe dope on everything threaded.

[john38706]

Re: 65 fuel filter leak

teflon tape will not work. the flare on the pipe is what makes the seal not the threads. like i said they need to be tight.

[John H.]

Re: 65 fuel filter leak

NPT (pipe thread) fittings don't have flares; they seal by thread interference, and Teflon paste on the threads reduces thread friction and galling, requiring less torque to get a mechanical seal.

[Clem Z.]

Re: 65 fuel filter leak

the use of teflon tape or pipe dope also helps in flare fittings not to help seal but to reduce the friction in the treads so you can apply more pressure to the flare faces. fuel line fitting into holley float bowl adapters are one place i have done this with great success.