I think I need 4.5" PV's from what I read about setting up duals. Problem is I thought I ordered some but now can't figure out which are what....
I'm curious. How did you arrive at 4.5 PV for a 2-2 application? I'm planning on a 2 carb setup on my 59ab truck engine.
Something I read somewhere in the past. Subject to verification. Makes some sense if vacuum is split between two carbs.....
I read the same thing and set my buddy's 94s up that way for his flathead. We haven't fired it up yet. I bought 3.5s and 4.5s and was careful to bag and tag them correctly. I'm thinking of buying a Moroso (or similar) power valve tester. Might be able to check the value with a hand pump and a good vacuum gauge.
"Charlie ny", the resident expert on Holley 94's (a**** other things) on the "Ford Barn" recommended to me to plug the power valves on the two 94's I have on the Offenhauser "Super" dual. I got the plugs from him. This setup is going on a freshly rebuilt 258 ci 8BA with a MAX-1 and the other usual speed stuff. I have the engine running, but don't have it in the car yet. I've worked with Charlie before, and that (and his stellar reputation) are enough for me. At the least, it's another alternative to consider.
Don't be intimidated by a pair of carbs, 2 - 2bbls = a 4bbl. They'll both draw idle air, each one will pull 1/2 of what a single 2bbl will pull. Remember, the engine needs 'X' pounds of air & 'X' pounds of fuel to idle, it has no idea how many carburetors there are to supply it and the vacuum the engine makes is what it makes, it doesn't know how many carburetors there are either. This is the black & white engineering side on combustion engineering and in the real world things will be a little different but if you grasp the concept it'll give you some confidence messing with them. I can do the math for it if you like, it gets involved, but its physics and beyond question.
***uming a flathead ? Usually 3.5 to 4.5 pv when two .94’s used. ( usually 7.5 with single carb ) As said, vacuum split as a ball park figure, - needs to be verified with a vacuum gauge under driving conditions. Some on here don’t recommend plugging the power valves, - that may depend on the specifics of the application - modern fuel ??? But Charlie ny is the known expert. why not plug the pv in a single carb application ? - why come up with the theory of splitting the pv for 2 carb ? Usually only secondary carbs are plugged on multi-carb set ups. link here to lots of information….. https://www.jalopyjournal.com/forum/threads/links-to-holley-94-technical-info.286574/ https://www.jalopyjournal.com/forum/threads/dual-94-carbs-on-a-flatty-setup-questions.36751/ read post 5 and 11 on this thread……. https://www.jalopyjournal.com/forum/threads/school-me-on-power-valves.205781/ sometimes the number is easy to see and sometimes difficult to work out. The pv without the raised lip is the correct one to use, with a decent washer. Some people machine off the raised lip to make it seat better. I check them by letting them sit overnight in place with fuel in the bowl. hopefully the above is helpful, - not confusing……
Are they different from 2100/4100 PV's ? If not, these guys have a bunch of flavors: https://quadrajetparts.com/2100-2150-power-valves-c-410_413_437.html The big end looks the same. I don't have a 94 PV to compare. Mike From Mac's "This power valve fits early Ford & Holley 94/AA 2bbl carbs correctly, along with the early 1957 up to 1963 Autolite 2 and 4bbl carburetor models 2100 & 4100. "
I like the 94s, I think once all set you're done-done for good too. Power valves are some of the most urban legend car parts in all of hot rod/Holley history. My opinion of course. In the golden age of motoring power valves were referred to as "economizers" and perhaps thinking that way can get us where we need to be. The only time I ever deleted em was a full race BBC with a Dominator. I cared only about WFO, din't need no stinkin driveability
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