QUICKFUEL FUEL PRESSURE REGULATOR - Q30-803 vacuum port thread size

[tonycap]

I have QUICKFUEL FUEL PRESSURE REGULATOR - Q30-803 that I want to use and the specifications say that the size is 1/8" NPT port for manifold reference, but
it looks way smaller than 1/8" NPT. The hole diamter is about 4mm.
Does anybody know the thread size as I would like to plug it off.

[edwardb]

Holley (Quick Fuel) website lists it as 1/8" NPT. I'd tend to believe that. Have you tried threading in a 1/8" NPT fitting? Given the design of NPT threads, it may/may not thread in very far. NPT's require thread sealant. But you probably know that.

[Jim1855]

Looks like that's a regulator for a carb. IT's a low pressure unit.
Do you need Manifold Pressure reference? Running a blower? I always run a regulator with a carb, never used manifold pressure.
1/8 NPT for Vacuum is fine and it is a small hole. This isn't for fuel.
Jim

[tonycap]

Yes it's a fuel pressure regulator that I plan to install on my Cobra as I am using a Quickfuel SS-650 carburettor.
When I purchased the regulator it came with no plug in the hole and when I looked at the instructions it said that it was a 1/8" NPT port for manifold reference.
I have a 1/8" NPT plug but it is too big so trying to see if anyone else has used one of these regulators and hopefully let me know what size it is.
Attached is picture of a 1/8" NPT plug sitting near the port on the regulator.
The instructions say the inputs and output of the regulator are 3/8" NPT and they are correct.
I really don't know why a company like Holley does not include a plug with the regulator.