390 Holley
03-01-07, 09:01 PM
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390 Holley
I spent the better part of an hour in the archives, and with dial-up, it's really not that fun... SO. I've got a 390 Holley sitting on a RB ported intake. Stockport 12A with 2.5" headers. I didn't give much thought to carb tuning since I knew I had vacuum leaks and it wasn't running right last year. Now that most of that is cleared up, I want to get it tuned for the summer! Can anyone direct me to a good starting point for jet sizes for my setup? I've got a Holly book on tuning on order from Summit, but if anyone can give me a starting point on jet sizing, that'd be great! I'm thinking of having it dyno-tuned just for my sanity of having it not lean-out and blow up on me soon... Thanks!
03-02-07, 03:47 PM
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On a stockport with a 390 Holley, I would probably start out with a 50 or 52 on the primarys. If you are running it with the power valve, you can start out a little smaller on the jets. Its better to start out too rich, then be too lean. If you e-mail Racing Beats tech support, they are usually pretty close with thier recommendations. But remember, whatever you do, keep checking the plugs during your tuning. If the plugs start turning white, your getting too lean.
03-02-07, 05:25 PM
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Racing beat never helped me much they took forever and never gave a straight up answer. im running a 465cfm 4150 carb with a streetport 12a and intake exhaust the works. Sam (bad83) and I went through every inch of my carb. well right now i havea 50cc accel pump (thanks Sam) and a metering plate where i can change out the secondary jets. I have #52 jets in the primarys and #66 in the secondarys. I also took the long yellow spring and cut the top off so its the same length as the short but it does not have the tight wound top of the spring. i think right now mine is running good Knock on wood. the plugs are great and its not loosing power or sputtering. I would start with #50s in the primarys and like same said keep a watch on the plugs WHITE IS BAD. LOL Good luck and any ?s pm me
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