I have a few questions about power valves----first what do they do----second how do U know which one to use---and I see that in each size they make a standard flow and a high flow --when do U use a high flow?
they piss me off, i use none of them, i would use a high flow to through it father into a ditch, then i buy a weber or carter or edelbrock. but when i buy the edelbrock one i take the tag off
With our carburetors we use the high flow ones in alcohol carburetors. We also use them in the E-85 and blow-through ones as well but in the standard gas ones.
They help "bridge the gap" between the idle circuit and the main circuit. They open at a certain vacuum level, which is the number stamped on the power valve.... a 65 opens at 6.5 inches of vacuum, etc. and is the factory installed PV in most Holleys. The only time I've had to use a different # than a 65 was when I had a condition where the car felt like it had a dead spot at low-throttle cruising. I used a vacuum gauge to determine that my big duration camshaft was only pulling around 6 or 7 inches at that point and the power valve was opening and closing when it should have been closed. Went to a 45 and cleared it right up. Hope this helps.
gary, if you go to their website their is lots of good info on their carbs! at least yesterday their was when i looked up a "renew kit".
I first learned about these gizzmos in the fords. They called them economizer valves and that explains them very easily. They give the engine a richer fule mixture at wide open throttle. The most important thing to know is the size of the valve such as 6.5. This is the amount of vac*** it takes to keep the valve shut. Anything below that will make the valve open and richen the mixture. When trying to decide which # valve you need for your particular engine combo simply put a vac*** gauge with a long *** hose on it in the vehicle with you. Take the car for a cruise and take a reading of the inches of vac*** your engine makes at cruising speed. Then pick a valve that will operate within this range of vac*** >>>>.
More importanly you need to check the vacuum....in drive....with your foot on the brake at a stop. If the cam is so big that it only pulls 6.5 inches of vacuum while you are performing this test and you have a 7.5 power valve, that valve will open while sitting at a red light and you will load up and run rich. It needs to be at operating temperature to do this also. no matter what you see at driving speed, the above needs to be taken into consideration.
thanks once I get the carb back together I'll try it I had a guy go over the timing and carb and he has things screwed up MY fault for letting someone else mess with my car (I was advised that he was a genius--HA) My carb had a 8.5 which probably was too high a number with my cam,but he put a 3.5 in it and later I discovered he kept the 8.5 I have a 6.5 I'm going to try
If the car has a cam in it just get a 5.0 . It will work perfctly. Power valve accounts for 4 jet sizes and allows the primary cu ircuit (in most cases ) to run 4 sizes lean under higher vacuum conditions. When vac*** drops at wide open throttle the vac*** that holds it closed is gone and the spring pushes it open allowing fuel to flow through the PVCR(power valve channel restiction) It is a good working set up. One can get creative with it to. But first we have to get you up and going with no trouble. if you engine is not cammed use the 6.5. If it is use a 5.0. Sometimes they are not available so a 4.5 may have to be used. That is as low as I ever go. Never let anyone touch you wife your wallet or your carb. Don
The Jalopy Journal
