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1954 Chris Craft MBL fuel pump inlet/outlet threads. Are they 1/8" pipe thread?

joe calcagno

New member
I am working on my 1954 Riviera Runabout with the original MBL engine. The fuel pump I found has 1/8" female pipe threads on the inlet and outlet. The fuel system has 1/2" copper tubing to carry the fuel from the tank to the carburetor. Could it be correct for the pump to have 1/8" threaded fittings? It seems to me that they should be alt least 3/8" openings. Could anyone help me with advice on what size inlet and outlet openings the original fuel pump should have?
Joe Calcagno
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Ayuh,.... 3/8" is pretty standard for fuel Lines, 'n 1/4", or 3/8" pipe is pretty standard for fitting threads, usedin boat fuel systems...

If the fuel pump has 1/8" threads, ya oughta be able to find fittings that are 1/8" pipe, to 3/8" barb fittings...
 
I'd be surprised if these were 1/8" TPT, more likely to be 1/4".
Take both 1/8" and 1/4" with you, and see which fits.

Dear Rick,
Thank you for your reply. I guess what I really meant to ask was if the fuel pump I bought, from a reputable Chris Craft boat parts supplier could be the wrong one since it has 1/8" female inlet and outlet openings. Since the fuel line is 3/8" OD, it would seem to me that the fuel pump should have 3/8' pipe threaded openings. I can certainly bush it down to 1/8" with fittings, but is it the correct fuel pump, or has there been an error.
Sincerely, Joe Calcagno
[email protected]
 
Dear Rick,
Thank you for your reply. I guess what I really meant to ask was if the fuel pump I bought, from a reputable Chris Craft boat parts supplier could be the wrong one since it has 1/8" female inlet and outlet openings.

Since the fuel line is 3/8" OD, it would seem to me that the fuel pump should have 3/8' pipe threaded openings. I can certainly bush it down to 1/8" with fittings, but is it the correct fuel pump, or has there been an error.
Sincerely, Joe Calcagno
[email protected]
Earlier you mentioned 1/2" fuel line, and I see that you now mention 3/8" fuel line.

With all of these fitting sizes, we need to know that ID, OD and TPT size do not necessarily correlate to one another.
Examples: the ID of a typical 1/8" TPT fitting may only be .220" ID, whereas 1/4" is roughly .280-.340" ID, and 3/8" is roughly .400" ID.

Asking a 1/2", or even a 3/8", flared tubing fitting to be secured via 1/8" TPT fitting, may be too much in terms of vibration, torque, etc.
And we have not yet addressed the potential restriction of the 1/8" TPT fitting ID.

I'd be looking further into the fuel pump p/n and make darn sure there is not a mistake here.
 
The fuel pumps have 1/8"NPT fittings. The lines had Uni-Flare fittings. They are now obsolete. Someone probably changed the lines and fittings.
 
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