Fuel pump threads (and regulator too)

[68 Sport Satellite]

What is the consensus on a leak free fitting type for both a Carter mechanical fuel pump as well as an Aeromotive fuel pressure regulator? The websites call out NPT threads and that is what I used after at first using straight threads (not AN) which leaked like crazy. The NPT threads are tapered and seal very well with a little pipe dope.

The reason I'm asking now is because I've seen more than one thread where some are calling out the use of an O-ring with the straight threads to prevent fuel leaks. Why not just use NPT threads as specified for the parts?

 

[68 Sport Satellite]

Bump

 

[Shorthorse]

There's a difference in these fittings. Aeromotive makes many different regulators. The regulator bodies are machined differently and specify by model whether the fittings needed are NTP or AN- O ring. Use what they say. You can damage the threads by forcing an NTP fitting into an AN o-ring thread. If you use an AN o-ring in an NTP thread it will not seal because the body is not cut to accept and seal the o-ring.

 

[coloradodave]

X2...