Q: I have a 1976 Chevy Blazer with a 320 hp small block. It has a 600 cfm carburetor, MSD 6A ignition with an HEI adapter kit, and a heavy duty distributor cap and rotor. I keep melting a hole through the distributor cap, plus the center terminal (spring included) and the arc seal.
I swapped in an ACCEL Super Coil, but I still melted things.
What can I do to fix this? Also, what should the rpm at idle be?
A: There is an easy fix for your cap melting problem. MSD makes a low-resistance distributor bushing, part number MSD-8412. This little part should help keep things well below the meltdown point.
As for your rpm at idle, it should be around 700 or 800 rpm.