Hey guys I'm new to this forum, and this summer I want to do a rebuild on my 78 400. I want a driver I can go down the interstate with but I'm also looking for more bottom end torque for being back in the hills and towing. I've been told I can replace stock rotating assembly and just use improved heads and an aftermarket cam and get better power out of it. Does anyone have any suggestions on what heads to go with, or what specs I should look for (i.e. cc chamber)? I live at 6200 ft and run an Edlebrock 4bbl. The truck is a heavy half with a NP435 transmission and a 9" with an aftermarket 'limited slip' rear end I bought from speedway. Thanks!

 

The main thing you need to do is get the compression up.

 

What would be the best size combustion chamber to do that without getting to where I will have detonation issues?

 

So..... I'm in the middle of doing this now, so I can tell you what I've found. For what you're talking about you will want to get ahold of Tim Meyer and pick up a set of his pistons at the very minimum. If doing a rebuild he sells a kit, which gives you a break on the piston cost. He's currently out of the .010, .020, .030 oversize but has .040 and .050 on the shelf. If you go to his website you can download the form and tell him what you want, he will put together a package for you and send it back. These will raise your compression ratio into a desirable level without becoming a ping monster. For what your goals are, I don't think you need different heads. You can do a little work to them like grind the thermactor hump out, bowl blending and cleaning up the castings and they are pretty decent heads. From what I have learned you don't want to port match because that will lower your torque, which is not what you want. Do the oil mods he suggests, go to a roller cam, it's a little pricier but I think worth it considering I just saved you from buying different heads. This should get you into the 350hp / 475 torque range which is pretty solid.

 

Why do you want yo replace your stock rotating assembly? Replace it with what?