Fuel Filter/Line Fitting Sizes, update Carburetor?

[dp320]

On the glass bowl fuel filter there is an elbow.  One end threads into the filter base, the other attaches to the gas line.  Does anyone here know the size call-outs for the threads?

 

I took my filter down to NAPA and amazingly they had a gasket that fit for $5.  The counter guy tried to find an elbow but he claimed the thread size was some oddball British spec.

 

The previous owner to me cross threaded the line side fitting so mine's shot.  The gas line is old and rusty but at least it still threads to the tank good enough.  I hate to go to a parts store because most of them all they know is what's on their terminal.  I want to replace the gas line too, seems to be maybe 1/4"? 

 

 

[Stoffregen Motorsports]

I have one I can look at for you. Tomorrow.

[dp320]

Thanks!  I checked the thread pitch on the end that screws into the filter--it seems to be 27 tpi?????  The other end is 18 tpi, not sure if it's an SAE standard or not though.

[Stoffregen Motorsports]

1/8-27 is NPT

1/8-28 is BSP

 

Ihaven't checked yet, but I doubt it is NPT. You could always re-tap it.

[dp320]

Yep, now I think it's British 28 tpi on the filter side. 

[Stoffregen Motorsports]

I looked at my filter assembly and it does not have the fitting you're looking for, just the pressed in nipple onthe other side.

 

If you can't find a fitting, just run a 1/8-27 NPT tap in there so you can use a fitting you can find. I would actually even go a step further and use a 1/8 NPT to -4 AN 90 degree nipple and modify the hard line by cutting off the old nut and slipping on a -4 tube nut and sleeve, then re-flare it and it's all modern. If you're worried about having AN looking plumbing in your engine bay, you can fbuy the fittings in many different colors and materials like plated steel for a OEM appearance, or silver anodized aluminum, etc.

 

 

 

 

[dp320]

I'll also have to decide what to do about the gas line to the carburetor.  That seems to be 5/16"-20.

 

Here's a photo:

 

 

Currently there is a short piece of tubing connected that was probably just cut. Next to it I'm holding a tubing that seems to be the correct fit all the way to an elbow (BSPT again) that threads into the fuel pump.  it's one of three I have all different.  The carburetor end with the ball is a bit narrower and is different material.  A previous owner cut the BSPT (tapered) side of the elbow.

 

 

The line from the gas tank to the filter is 20 tpi, Male OD of .435 (.4375), Female ID of .384 (.390).

The line from the fuel pump to the carb is 20 tpi, Male OD of .490 (.500), Female ID of .439 (.453).

(Chart numbers in parentheses.)  My caliper measurements could easily be off.

 

Like you said I could get fittings that convert.  Since I found a place online that has the British stuff I think it will be easier to get them.

 

 

The tapered side of the two elbows are both a good match at 28 tpi, major OD .390 (.383).