mpresme333

Hey fellas i have a 670 hooley tbi, i have no instruction manuals for it but i was wondering if there is a way to adjust the fuel pressure on it, the pressure regulator just has a brass button on the top there is no srew or anything, i am not even sure that it can be adjusted, before i buy a billet jet regulator form summit i want to make sure i am not wasting my money! ya know! Thanks!

HaulnA$$

Yes it can be adjusted. Just drill a small hole in the brass button and pry it out. There is an allen screw in the regulator to adjust it. I did this to mine. Works great.

mpresme333

ohh okay i will try that thanks also do you no what the max psi rating is for the holley tbi stock regulator?thanks again

HaulnA$$

I have not been able to find out the max pressure that the Holley FPR will handle but I do know that it can handle much more than your stock fuel pump can put out. You will be lucky to get more than 20# of pressure from the stock fuel pump, less if it is old and tired. I would venture to say that the Holley FPR could probably handle at least 50# of pressure if not more. It has a pretty heavy duty spring in it but I don't think injectors could handle more than 40# or so I've heard.

r90camarors

The holley regulator is rated from 9-22psi. I've gotten 25 psi outta it w/ my walbro 255 fp. You can change the spring out to achieve higher pressures.

JPrevost

The highest pressure I was able ot get out of it with the stock spring and no vac ref was 18psi, anything after that (even with the walbro 255lph pump) was just the spring bottoming out. The spring was replaced and I now have 28psi .

HaulnA$$

My 670 TBI is the old Holley commander Analog type (had to have it machined to accept an IAC Motor) with the old style 85# injectors. Holley also came out with the GM OEM replacement models (such as the 502-6 for pickups which I put on my sons car) and new style injectors . When I compared my TBI to the one on my sons car, they were quite different. Not only were the injectors different (his had the newer style injectors , and they were only rated at 65#), but my TBI FPR had to be modified to be adjustable and had a much stiffer spring in it while the newer one had an OEM style throttle linkage on it. I was not able to get as much pressure out of the newer one as I did the older one. This might explain some of the differences that people have seen and why some people have a harder time tuning these TbI's. Maybe not. Just thinking out loud. Anybody else see this? I'm curious.