Given that Pony Carbs is no more, I do not know who to turn to for carb questions. Can anyone comment on the appropriate size power valve for Holley 4150 (9510-D list 3796) for '67 390 Automatic mustang applications? When originally rebuilt by Pony Carbs, a 5.5 power valve was installed. I am now going through the carb due to my stupidity of allowing fuel to sit in the carb too long. The power valve which cam with the Holley "renew" kit is a 6.5. I do not know how sensitive this application might be to the power valve size. As I understand it, the larger size valve will open sooner (i.e. under higher manifold vacuum). What I don't know is whether or not Pony Carb installed the 5.5 valve because they knew that was the correct size or if any valve in the 5-8 size range will work just fine.
Help?
