QUOTE(SLITS @ Mar 29 2011, 07:57 PM)
Don't know much about the HEI and why one runs a relay to power it. If it needs 12V, then a direct connect I would say. The black wire is already fused with an 8 amp fuse at the fuse block.
If it's to run a fuel pump, then that's a different story. If the FP draws a lot of amps, a relay to activate it allows for a larger gauge wire to be used directly from the battery to power it.
Oh, I threw away the HEI and used a point style dizzy on my 8s. For multi-spark, they were only good to 3 or 4K before they wimped out.
I wired one of my sixes through the /4 relay board, matching wire function of a 4 cylinder engine harness to a six cylinder engine harness. Understanding the function of each wire made it reasonably easy.
One six I'm working on, they cut the wires where you did. They are spliced, again, but follow function (but the original builder didn't hook up all that is necessary).
Anyway, a VOM is your friend. Use it and study wiring diagrams. It'll keep you off the street.
Oh, the other fuse on the relay board is 25 amp and used for the fuel pump circuit.
Thanks for the reply. I think you're right about the relay... might be overkill.
If I looked at the fuse block part of the diagram correctly, the black wire connects at the block at the point just before power passes through the fuse (on its way to power things like the windshield wipers and cig lighter), therefore, I don't think the black wire is fused. On the pre-fuse end of the block, there are 2 wires connected, one from the ignition switch, which I believe energizes the fuse and circuit, and the black wire that goes to the relay board and energizes the above mentioned relays etc...
If the relay way is overkill, then maybe running the black wire directly to the BATT terminal on the HEI is better. If I go this route, I believe a fuse must be placed between the fuse block and the HEI. Any idea on what amperage fuse and gauge wire would suffice?