Holley Fuel Pressure Regulator


TL;DR: Another easy fix

The other day the car broke down in our alley, preventing us from attending the Distinguished Gentleman's Drive. Deleting the fuel pressure regulator seems to do the trick, but I'm not sure the Facet cube fuel pump really remains within the allowed pressure range for the Weber carburetors.

Today I opened the Holley regulator to check what happened to it. It's clear that the diaphragm has seen better days, now rather rigid with a skewed resting position.

The casting reads 34R 6657B, and the Internet told me it's compatible to the current 12-804 for which diaphragm repair kits are readily available. An interesting option would be to use one that is fully compatible with ethanol (E85). That would make it absolutely safe for modern fuel that has between 5% and 15% ethanol in it.

A good source for a standard kit would be gooze.com, in the Netherlands (14€ for the parts, 6€ for shipping).

Before committing to that repair, I ordered a 1 bar/15 PSI "filled" fuel pressure gauge, that I will install in-line just before the inlet of the Webers. It will tell me how much the low pressure Facet pump is really pushing, and if I need to get the regulator back in the circuit. In any case, I would need the gauge to adjust the regulator after service.

October 17-18th:

The gauge was too tall to fit beside the Webers, I will have to locate it lower (upstream).
Nevertheless, it already allowed to determine that the pump pushes 6 PSI, which is 2 to 3 times too much. Time to place the order for the Holley repair kit!

I gave the Holley some TLC: fully dismantled, removed and brushed out all the teflon. All the parts were then cleaned in an ultrasonic bath followed by a proper dry in the dehydrator. The exterior was protected with WD40, properly rubbed in. Interestingly, the casting of the bell shows that it was made in Japan.

October 22nd :

With the repair kit not in stock and no clear date in sight, I had the order cancelled by e-mail to get a complete new regulator instead. I will transfer its innards and screws to the vintage Japan-made casing.

More to come soon...



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