Here's what I did with my last 390: Stock 68 390 from a Merc Monterey (10.5 to 1 comp ratio) Stock C8AE-H heads, 428 PI intake (the RPM will do as well) Holley 3310 750 cfm carb, cam was a Crane 272* Energizer, stock valve springs (they didn't need to be changed with 58,000 miles on them) FPA headers (only brand that fit the big Merc) This motor needed 93 octane fuel with the stock cam, 89 with the Energizer. Only had a hint of lope at idle when cold, pulled from idle to 5500 rpms. 14 sec 1/4's in the 4200 lb Merc with a 3.70 geared rear. I ran a similar 390 in a 70 F100 back in the 80's but with a slightly different cam which is no longer available, but it had a 290=something duration and .523 lift. This one would run on 87 octane fuel with 10 to 1 compression. Basically a GT390 cammed up a bit with a 428PI intake and 750 Holley. As I recall it ran 15 sec 1/4's with a 3.50 rear in the F100. Would pull anything you hooked to the bumper.

 

Thanks for the specs Baddad. Did your '70 run okay on 87? And isn't the 428 PI an aluminum intake

 

Remember a large percent of your power comes from the top end, just keep in mind that 75% of your intake runners are actually in the intake on an FE motor. As far as gasket matching just something I learned is that most of your gaskets are for FE motors in general, so a good chance they are going to be larger than your 390 head on the intake side. I didn't take anything out of the floor of the intake but just cleaned them up with 60 grit rolls. I did smooth out the exhaust and bowls. I also put hardened valve seats in, gas today isn't kind to the old seats. Like I said, you'll get everyone's opinion and thoughts...... That's the great thing about this site.. Everyone is an expert... lol! I don't know when your going to start your build but I'll be more than happy to share what I have done to mine including part numbers and such. Not claiming to be the "expert" but I can give you TESTED facts on a RUNNING engine. I'm not going to the strip so can't help you with expected ET's. Good luck with your build!!

 

Yea, the 70 was fine with 87. The PI intake is aluminum. The RPM is it's equal. Power will come on from idle to whenever the cam is done, despite what the advertising says (1500 to 6500) There's no loss of bottomend vs the Performer 390, only a little more "oomph" on the topend. The 68 Merc's motor was basically identical to the GT390 I had in the 70, the cam was the only difference. I never tried it, but the Merc's 390 may have run on 87 too, if I had backed off the timing some. It was fine with 89 with 12* initial timing in the stock distributor (fitted with a Pertronix)

 

I will be building this (hopefully) at the end of July. I'm kind of having to save up money (odd jobs and such) until one of the places I applied to will hire me on for the summer (1 of the 23). I want a clear plan so I can start accumulating the different pieces (if I see an intake or something pop up on craigslist). The only reason I was curious about E.T.s was for an estimated horsepower rating.

 

I know how it goes saving for the big build... The cam I used is a Lunati Voodoo #62003. RPM range says 1600-5600 but she'll probably pull a tad more before she floats the valves. Sounds like you have a pretty good plan so far, I went ahead and upgraded to all MSD ignition to be safe. Keep us posted as you build, we all like to see projects come together.