I was told by Holley that back in the sixties or early 70s that the 390 cfms were used on some 390 fords and 440 mopars as well. I believe I jetted mine up too 57s in front and left the secondary side alone so sounds like you hit the mark as well.

-Gary Burnette-

You might also consider adding a phenolic spacer when you switch carbs.1 inch is sufficient provided you have enough clearance between air cleaner and hood if you are using the original aircleaner which,by the way can be used with the Holley carb.Keeps the carb a little cooler by isolating it from the manifold.

  

Thanks for the feedback guys ,and the jetting info was a bonus ! I'll order up the carb this week.

Pete

Hello Gary! On mine I went from the factory "512" primary jets to 54 and then to 56 which seems to work fine.Never touched the secondary side at all.The 8007 is rated for engines right up to 350 cid by Holley.

  

The 390 cfm will more than take care of the stock 312. that's what I'm running in my 56 sunliner and it doing Great. The only thing I did was jet up the front primaries a few numbers higher and it very responsive.

-Gary Burnette-

I believe the 390(model 8007) comes with a little bolt-on  "stud"adapter so you can clip on a throttle cable as opposed to the rod type linkage original on many 50's Fords.I am happy with my 390.Electric choke and either full or ported vacuum hookup for the distributor advance as well as the aformentioned PCV hookup.If you ask 6 people for their preference on carb manufacturers you will likely get 6 different answers.If you log on to the Holley website you can order a free catalogue with lots of info about their carbs(and other interesting parts)Hope this helps.

  

525 Road Demon jr. is what I run, very good carb.  Looks good too. 

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

YOU ASKED FOR OPINIONS so here is one. I have a 312 with a mild cam and FOM with a 3,31 rear gear in my 55 Tbird. I put a Holley 600 vacuum secondaries on it like 15 years ago and I never regretted it. The carb was model 1850 AAS and came with the Ford style kick down linkage ( You obviously will not need this). I have the 57 Tbird tach drive distributor with a pertronix I igniter in it and run full manifold vacuum to the advance. A four barrel carb will run on the front two primaries 90 % of the time, so what you really have is 300CFM two throat until you floor it. Then ask your self 390 or 465 or 600, what was I thinking? It is a very docile carb and very forgiving. With a T5 and 4.10, why even ask? Pete

So Mark how do you like the 390 ? I have looked at the 465 Holley but the throttle arm has a very small lever that won't work well with the throttle cable that I am planning on using, so it's the 390 or the 600 for me.

Pete

The vacuum port for PCV is built in on the 390 which is what I have on mine.