L78CHEVELLE
Senior Member
Here are some things I have found out about power valves and jets for the Holley 94 carburetor series 91-99 Ford used in 1940. The standard power valves Ford used with the 94 carburetor was 7.5. The standard jet size is 51. I will not go into all the details about these two pieces just to save time. One of my original 1940 cars was smooth but no acceleration. I took the carburetor off to check its condition and found the power valve to be a size 5.5 and the jet size to be 51. I ran a vacuum check on my car and it has 20 inches of vacuum. Holley says to divide the vacuum reading I get by 2 and that is the power valve size I need. I discovered the largest power valve you can put in a 94 carburetor is 8.5, unless you want to make modification to the carburetor body in the area the power valve plunger functions. I installed an 8.5 power valve with a nylon gasket made for a Holley 94 carburetor and reinstalled the carburetor. This change I made to the power valve size brought this car alive. Acceleration is much improved with the only negative being less fuel mileage. I have even taken the carburetor off again and installed a set of 53 jets, which made the car run even better. If you would like more acceleration from your Holley 94 carburetor try the vacuum test and check your power valve and jet size. Maybe what I have learned will help you get more performance out of your car. Just for the record, I did the spark plug test after I installed the 53 jets and my plugs are just a slight tan color. More power and less miles per gallon is OK by me.
