You can get Holley Power Valves at most
good parts houses...
8.5 sounds aboot right to me...btw they are rated in inches of mercury(vacuum), not psi.
The rating is for when the valve opens, and allows more fuel to flow. An 8.5 rating means the valve will open at approx. 8.5 inches of vacuum. The valves are stamped on the metal part with the number. Most higher HP engines have cams that don't allow a lot of vacuum, so therefore they would use a lower number valve. If you have a cam with a lot of "lope" to it, and a lower numbered valve, the valve will just sit there and dump fuel all the time. IN that case, we would always just remove the power valve, plug the hole, and jet the carb up a few notches...not exactly a good set-up for a street car, but it works well on drag cars, or boats!
Hope that makes a little sense.
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Joel Adams
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