holley 390 jets


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By 'GB'ird - 15 Years Ago
Hi

Just bought a Holley 390 for my 292 (with a Mummert 265 cam) as I wasn't happy with the old '57 Holley #1273. Out of the box the 390 comes with primary jet size 51 and I'm thinking this seems a little lean, although I haven't fitted it yet. (The secondary jets are 53). Does anyone have the same or similar set up who could offer some advice on jet size as i'd like to try and get it 'right' if possible before installing it.

Cheers

Richard

Chelmsford UK

By oldcarmark - 15 Years Ago
The .512 jets are what they come with.They are too small.I changed mine to .54 and then .56.You need to go at least .54 to see a difference and they worked great.I went to .56 just to see if there was a difference-not too much but it was not too rich either.i would suggest starting with the .56 as yours is not a stock cam and see how that works.When you take the fuel bowl apart don't overtighten screws when reassembling.No problem on mine but it doesn't take much to damage the threads in the body.The 390 worked great on mine.
By 'GB'ird - 15 Years Ago
Thanks Mark, appreciate the advice.

Cheers

Richard