Chevrolet: Ram Jet 350, gm crate engine, spark plug wires

Question
Jim.

I recently purchased a ram jet 350 GM crate engine for a project I have been working on.

The engine works great except for the following.

The headers turn red to white hot at idle? So much so that it is burning all my spark plug wires even with insulation on the headers and on the wires. I have other small block chevy's with headers and this is not a problem.

What could be causing this problem.

Engine temp is normal.

Regards.

Answer
Brian,
      The thing I would look at first is what type of system you are running post header. Everyone always talks about backpressure, but what that really is is a by-product of EGP, or exhaust gas pulse. This is a condition in which the exhaust gas cools slightly as it exits the system, which in effect actually pulls the next pulse behind it. Too big of a pipe, and the exhaust cools too quickly and doesn't pull right, too small a pipe and it backs up heat into the headers. Especially for a high performance motor, the system post header needs to breathe freely, with the right size pipe and a relatively free flow muffler. A 77 Chevy pickup I built a motor for a while back - I started out with 1 1/2" pipe, and the headers melted a couple spark plug wires. I went to a 2" pipe and a set of flowmasters, and never had the problem again. It is kind of tough for me to really know without knowing what the project is or the post header system, but if the headers are heating up like that, and the coolant temp is normal, it sounds like a restrictive/restricted exhaust system.