'72 GMC I6 to V8, motor won't stay running, wiring issue?

[glock35ipsc]

Originally Posted by grancuda

A week ago the motor was in a different truck, running great and now all I have done is pulled the intake, cleaned up the motor and put it in mine and put the Performer RPM on and I put it back together and now it is doing this. Anyone have any ideas?

You just found the things you need to rule out then. If it ran good in the other truck, and now won't run in your, look at what changed. Are you using the distributor that was on the motor, or a different one? I don't recall if you said you ran a new wire to the HEI, one that is a solid 12v from a switched source?

If you can get it to run at a constant RPM, like adjusting the idle screw to keep it there, go around the intake gasket with a can of ether or carb cleaner or something to see if the idle changes. That would help to pinpoint a vacuum leak from the intake. Is the intake new or used? What gaskets did you use?

Double check the distributor also to be sure it's not a tooth out.

If all you changed was the intake, carb, and distributor.... you have ruled out the carb it sounds like. Rule out the distributor (either a mechanical/electrical problem, or one tooth off), then check the manifold.