Clams Canino

Small block.
My tech dood recommended AC Delco R45TS gapped at .035.

Any dissenting opinions??

-W

Clams Canino

The more I read here... seems I ought to increase gap to .040.

Again any good opinions here?

-W

70Speedray

I am working off of memory, but I believe the early HEI engines had the plugs gapped at .060", then GM backed the specs off to .045" for later HEI years.

Essentially you want the largest gap that an ignition system will fire consistently. The .045" gap will give you a higher energy spark than the .035" gap. (A larger gap requires more potential to build up before it sparks, creating a more concentrated, more powerful spark when it does finally jump the gap.) So, I would suggest .045" as a starting point.

Shark Racer

I've always gapped at 0.045" with my 78HEI, and that's what's recommended.

drwet

If I remember correctly those huge plug gaps (.060 and even .080) were used back when mixtures were lean and compression was low. .045 should be about right.

Clams Canino

Ya.. I went about .045 Runs well. THANKS!
Timing thread to come.

-W