New Carter Fuel Pump. Inlet, Outlet

[Leo B]

Hi,
I bought new Carter Fuel Pump. New one has bigger outlet and inlet than original. What are correct Inlet / Oulet Fitting sizes? (both are same size). I measured female 0.441-0.447 ".
Is the correct 1/4 NPT?

Edit: From the very top female is 0.49" So have to be 1/4 NTP.
https://help.summitracing.com/app/answers/detail/a_id/4826/~/what-is-an-npt-fitting%3F

Edited March 15, 2022 by Leo B

[Dwight FitzSimons]

It shouldn't be an NPT (pipe thread).  Fuel shouldn't be run through an NPT fitting (too difficult too seal).

--Dwight

Edited March 15, 2022 by Dwight FitzSimons

[Leo B]

Then... Is it 1/4 NPSF?
https://pitstopusa.com/i-5063641-carter-mechanical-super-fuel-pump-sb-chevy-7-5-8-5-psi.html

Edit: Maybe should be NPTF.
Im quite confused because almost all sells NPT.🤔

Edited March 15, 2022 by Leo B

[Dwight FitzSimons]

The website pitstopusa describes the inlet and outlet of the fuel pump as NPSF (not NPT).  NPT has tapered threads, NPSF has straight threads.

--Dwight

Edited March 17, 2022 by Dwight FitzSimons

[John C]

Hello Leo,  Every mechanical fuel pump I have installed on cars prior to 1975 have always been NTP. It is a taper thread so use a good sealer like Loctite 567 and install it snug and it will be fine. Never use teflon tape on them.   Good luck, John C.

[64studeavanti]

I would have guessed that it was inverted flare. Lo and behold when I looked at some spares in the shop, they appear to be NPT. No seat to seal! OTOH, the fittings that go into the pump are inverted flare.

 

FWIW, I have had success using hylomar as a sealant.

Edited March 16, 2022 by 64studeavanti

[Leo B]

Thank you gentlemen. I see only way to solve this is to use 1/4 > 1/8 NPT Reducer adapter fitting + Loctite or Hylomar.  I have Out T-fitting (cross) and In L-fitting (elbow) from older Carter. All older fittings seems to be tapered and appears that a sealant has been added to them.

[Dwight FitzSimons]

Here is a pic of the original Carter fuel pump off my '64 Commander 259, showing its brass fuel fittings.  I believe your car is an Avanti, so your fittings may be different.  I would suggest going to Studebaker International or Stephen Allen's (or others) for these brass fittings.  These, of course, are SAE (English units); We ain't had metric here in the wild West for very long.

 

--Dwight