Thread: 390 valve clearance

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Help!!! I am trying to figure out what kind of valve clearance I can get away with using stock style pistons and stock deck height with the old iron heads I have for my 1966 390 Ford motor. I need substantial lift as I will be campaigning this motor in a 65 Falcon bracket racing car. I am looking at cams in the .520 to .540 lift range, but don't know how to figure out if I'm going to be slapping my pistons with valves. I don't really want to order a cam if it won't work-soooo- I am trying to make peak torque between 4500 and 5500 rpm--any help greatly appreciated!

While lift does make a difference, it doesn't affect valve to piston clearance as much as duration and lobe separation. You need to measure the clearance to know for sure.

The lift I am looking for is substantial compared to stock cam lift, and I am trying to not have to order the cam until I am sure it won't cause clearance problems. The cam is not returnable once installed, so I am looking for a ? mathematical way to come up with a safe lift range in my essentially stock block and heads. I can get the cam and measure clearance with it installed, but may be wasting my money. That's the catch. I don't know if someone has a way to estimate or to know for certain what kind of lift I can sneak past the pistons in this setup.

Do you have the Steve Christ book "how to rebuild BB ford engines"? It specs all the stock cam lifts and all are under .500 with .499 being the largest and for the 427. What year 390 and which heads do you have? I'll give you the specs if you like. G.

I don't have that book. I figured on going well past a stock cam in terms of lift and duration to get peak power between 4 and 5000
rpm. The engine is a 1966 and it came factory with a two barrel. As far as the heads go, I haven't found any numbers to i.d. them. I do know the engine was bone stock when I got it though. Don't know if there is any difference in two and four barrel fe heads. Btw, will a set of 360 heads work as a drop in for my 390 if I can get them???

The 360 heads will work on the 390. In some cases they are the same heads on different engines ie: 360-390-428. The casting numbers are in the center part of the head by the exaust ports and spark plugs. They will be C8AE-B or A, D2TE-AA, D3TE-B,C,E,F These are some of the numbers for a 360/390/428 heads. The cc's vary a little from 67.1- 71-1. Also I'd change the springs to match the cam with more lift. A little more $$$$ now will save you much later. The stock springs are crap anyway. JMO, G.

Thanks for the location on the #'s. Mine appear to be the d2's. Found out today that up to .600 lift (with matching springs) can be used in the original heads. Machine shop is suggesting I go with rocker shaft studs instead of the bolts. I would really like to find an older intake to use to help keep the "old" feel to the car, but haven't had much luck locating one that will flow good enough. Again, thanks for the advice-in a couple of weeks it will be "Off to the Races!!!"

I like the sidewinder intakes myself. Still to this day an excellent runner and can be found for around $350 in good shape. On ebay I've seen them go for $500 good used and $800 nos.Swap meets are good for old stuff. Sometimes you hit it right and score a deal. The PI is good and seems to be the standard. If you don't mind the weight a old iron CJ manifold is good to. Same as the PI except CJ's iron and PI aluminum. Some of the vintage Edelbrocks are cool or the newer RPM or Victor. I run an old tripower setup on my "63" 406.myself. G.

The weight won't be a problem- I've still got 650 pounds to get me to the 2650 weight mark. I would like to take a close look at one of the old cj manifolds. Think that would be pretty slick.

Oh- just remembered- a friend of mine has e decent set of heads that appear to be 390 heads but the casting #'s are c6me-a. I looked on the Fairlane sir but didn't see them listed. Any ideas?

I see C6AE-A for 390 heads which is the std 352/390/428 head. Sorry no C6ME-A is listed. All I see for C6ME-A are 390/428 block numbers. Let me poke around in some of my older books and see. Check out www.dscmotorsport.com for intakes. He has some old iron CJ's for sale. Dennis has great parts and service. Prices good also. G.

I've got c6aeu for a block and c6me-a for heads.(the odd set).
Might have those #'s bassackwards though. That DSC site is great! Thanks a ton...

Yep the AU # is for your heads. 68 Merc 390 4v/high compression 2v. Measure your cly bore to verify as the C6ME-A casting number is used on the 325/360/390 and 428 blocks. 4.00 is 352,4.05 is 390and 360 and 4.13 is 428. These are std bore sizes so take overbore into account. This way there is no question what block you have. G.

The block went to the shop friday to be cleaned, bored, cam bearings installed, freeze plugs and a few other goodies to perk her up and hold it together. They measured it and it is a 390. If the rods chack out o.k. I think I'm gonna have some 10:1 slugs waiting on them when they get home. Forged flat tops w/ valve reliefs. I'm considering a 100 horse nitrous plate kit but want to wait and see what the motor will do by itself first. Again, Thanks for the help FFR-it has been much appreciated!