HEI Plug Gaps ?

[oldcanuck]

Guys,

HEI conversion done and running very well..... just one question since I am getting conflicting plug gap information.

Being the stock plug gap spec is .028 to .032 for points, I have always been under the impression to add about .005 when converting to HEI...... so I gapped my new plugs at .035 during the install. A local dirt track engine builder told me that I should run them up to .040 even .045 for more spark and the Hi Po will be much happier.

What say the Fourm experience here ?

As always.... thanks for your advise.

BG

[shelbydoug]

It doesn't matter. Try the .045, then read the plugs. That gap was for emissions reasons and it in theory runs the exhaust cleaner. It could also burn a hole in the piston. I tried it once. Don't need it.
Run .035.

[The Going Thing]

.035 is the standard plug gap. I utilized the Pertonix II. I run a .040 gap. Burns nicely.

[oldcanuck]

If I run .040 or .045 will I see just a little more engine temp on the gauge ?

I doubt I would go .045, but seriously thinking about .040.

Thanks all.

[shelbydoug]

There should be no noticeable changes. The hotter spark is just for more complete fuel burning. You will need to have the facilities of NASA to detect or measure it.

When you are making 14 gazillion vehicles a year, the total difference is measureable.

You may show more deposits on the electrodes depending on what's in your fuel?

[The Going Thing]

Many of the GM HEI equipped vehicles used .040 to .045.  I agree. Try the smaller than the larger initially. Stay with what runs the best.