Thread: I, too, must rebuild my 390, but have ???

Tweet

"I have no idea what cam to use. I don't know if the Edelbrock cam (.460/.480) is too small or the Comp/Crane cams are too big. How do I decide this?"

In my opinion, the most important aspect of choosing a cam is matching it to your static compression ratio. If you have a low c.r. and choose a cam with a late intake valve closing, you won't build enough cylinder pressure to pull the hat off your head. On the other hand, if you have a high c.r. and choose a cam with an early intake valve closing, you'll build excessive cylinder pressure and you'll never get it to run on pump gas (severe detonation). Go here and read up on cams. I started writing it a while back and although it's not finished, there is some good info:
http://streetmachinesoftablerock.com...topic.php?t=78

As far as pistons, unless you're really gonna beat on the motor, cast pistons will work. If you want to step up a little, use hypereutectics. Forged pistons are overkill for the street and due to the clearances you have to run to make them work, they're very noisy on cold start-up and much more expensive than cast or hyper pistons.

To figure your compression ratio, see this paper that I wrote:
http://streetmachinesoftablerock.com...opic.php?t=124

By the way, your heads were originally produced for a 1963 406 High Performance motor. The chambers will vary between 64 and 67 cc's.