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I've been having a tough time getting fuel filter to seal up on carburetor and hoping for some advise.
As can be seen in pic, part of the issue could be the metal fuel line being off a little bit and the filter bending slightly when all tightened up. In the past, I've had some luck with the Fram G3596 seating up when torquing the heck out of it (filter on far right that has a profound lip between threads and body). I've simply been unable to get the other 2 filters in pic to seal up (Wix and Microguard). Anybody have luck applying Permatex 85420 "Fuel Resistant Gasket Dressing" to fuel filter to carb threads; maybe letting it cure over night and then install line?
Thank you in advance and any ideas would be greatly appreciated,
The carb & fuel filters should be NPT (pipe thread) and you only tighten it enough to not leak.
Thing is in the past someone has tighten the filters to much so the pipe part no longer works.
I think if it was me I would find a fitting that screws into the carb and you can put the fuel line into it.
Then I would add a "in line" filter between the fuel pump and carb.
The line should be 5/16" and the makers of the screw in filters also make in line filters that come with 2 short rubber hoses & clamps.
Cut the line, de-bur it and install the filter.
When you hook the filter up bend the line so it dose not pull on the fitting in the carb.
Have you tried bending the line so it dose not pull on the screw in filters?
I would still do the fitting and inline filter so you dont have to mess with the carb threads again.
Dave ----
Thank you for the insight, I was actually thinking of doing something like this. I have not yet tried bending the metal line as currently it is sealing on flange to fuel pump and flange to fuel filter well.
Looks like there are some barbed male fittings that will screw into the carb and allow a rubber line to be installed. The only leak, is the small threaded portion between filter and carb.
You've got tapered pipe threads where the filter screws into the carb housing. The taper makes the two pieces wedge tighter together the further the filter is threaded in.
Make sure the female threads are good and clean. If blocked with debris, the filter won't go in far enough for proper wedge action. If there's any question about the condition of the female threads, clean them up LIGHTLY with an 1/8" NPT tap. Don't cut more than a 1/2 turn or so, as the taper will expand the diameter.
My truck's 351W has the same filter arrangement and I've had to clean up the threads as described. I've also used a smidge of Teflon thread compound on the joint. Apply to the male side, leaving the first two threads bare. Do NOT use Teflon tape, as slivers will end up in the carb. Paste is fine, though.
Keep in mind if the condition of the female threads is the root cause, you'll still have the same leak if you switch to a barbed fitting and remote filter. The female threads have to be in good condition to seal properly, no matter what is installed.
Looks like there are some barbed male fittings that will screw into the carb and allow a rubber line to be installed. The only leak, is the small threaded portion between filter and carb.
That Dorman fitting is the wrong arrangement to thread into the carb. That piece has straight threads that provide clamping action only, to force the machined end against a matching female seat. The threads themselves provide zero sealing action, only clamping force for the end to seal.
If you go with a barbed fitting, you will need 1/8" tapered NPT threads to match the carb bowl. This is a common part, available at any hardware store.
Thank you both, as I'm starting to understand this better!
It makes sense to me that the the misalignment from the rigid fuel line is making things much worse. Once the fuel filter bends enough, off the axis of the carb body's hole when the fuel line is torqued to filter, it will return to a fixed position (and prevent any further tightening from filter to carb body). This now explains why once the fuel filter is installed, and gets a good bend in it, it will never seal back up again if removed/reinstalled. Sounds like I'm gonna need to 1st realign and/or replace the fuel line and then consider cleaning the female threads with a 1/8 27 NPT tap.
If you are going to use any type of sealer on the threads, shy away from thread tape and go back to the original idea of permatex. Thread tape can work fine, but it's risky. It''s very easy for a piece of it to break off the threads during installation and it goes up and gets caught in the needle and seat of the float. Then you can suddenly have flooding problems.
I got tired of the stock filter setup and bought a brass fitting that looks just like that from the parts store. It threaded into my carb and I've been using it for 3-4 years now with an inline fuel filter. Got another one on the fuel pump.
Either my fitting has the right pipe threads, or it somehow seals enough to not matter. Never leaks. Lol. I think it was from an oreilly's.
I wanted to show my gratitude for all the info on this, it has helped me resolve the fuel leak; something about gas streaming down the exhaust manifold made me feel a little uneasy.
I did order a 1/8 - 27 NPT tap and some brass fittings to fix next time it leaks, once and for all. Though, for the time being, I did let Permatex cure for a few days and it's holding the stock filter screwed in for now; I was able to bend the fuel line so it is not applying lateral pressure on the filter.
I'm thinking the tap will renew the threads and will simply require a longer fitting to seal up (the brass fittings I ordered can screw in much deeper than the stock filter).
I truly appreciate the wisdom in this forum and have learned a thing or 2 from this experience.
