... put a guage in line to check the pressure.
If you have a modern replacement mechanical fuel pump for Y-block or FE engine, those pumps have an output pressure of 5 - 7 psi which is more that what you want, so you would need a regulator to keep the pressure below 4 psi. I don't recommend any regulators available from the chain auto parts store
s.Airtex offers a 6-volt electric fuel pump with 2.5 - 4 psi output pressure part #E8902, but you'd need to remove your mechanical pump and install a block-off plate and use the electric pump full time. You can but the whole kit, part # E8902K from Vintage Auto Garage so you don't need to get fuel filter & fittings separately.
Kultulz, the guage is just to check that the pressure is correct with the engine running, not too low or too high so you know its the correct spec for the carb, and the pump spec is correct.
When you shut the engine off the pressure usually drops
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Maybe read TECH on a DEAD-HEAD and BYPASS REGULATOR.
At the time when I was looking for something different from what I had been using, I did look at Summit and Jegs, but they offered the same types I had already tried, but that was ten years ago. I even had an expensive adjustable Holley regulator with integral pressure guage but it blew up too. It didn't last any longer than the cheapies I got from the chain auto parts stores.How about if I ordered a Offenhauser reg. or any other reg. from the manufacturer. would that be junk also. How about Jegs, Summit. They must get the "good" parts!
... ended up designing a complete fuel bypass system back to the gas tank, by using an orifice in the carb supply line to direct excess pressure to a tee in the line ahead of the orifice. From there, I hung a whole nother fuel line back to the gas tank.
Miraculously, it has worked without any trouble the past ten years.