I'm running Delco R44T plugs @ .45 gap in my street only BB and have for years. Iron heads, HEI ignition. Time to replace plugs and wondering if anyone has a suggestion for any other brand or gap or am I ok with what I'm using ?
Gap is moderately unimportant provided that it isn't in excess of about .045.
Larger gaps were used by GM--in fact all the way to .080 (!!!!) but that was on engines with nothing-to-one compression; a palletload of EGR, lean fuel/air ratios, and overall, NOBODY expected (or received) any horsepower from those engines. They tended to melt distributor caps and they were hard on ignition coils and plug wires.
If you have enough gap to light the mixture--you're probably OK. Too much gap in an engine that has REAL CYLINDER PRESSURE is going to cause misfire. Too little gap is probably not as bad as too much although I don't recommend closing up the gap excessively just to prove a point.
Pretty much anything from .025 to .045 should be acceptable; provided the side electrode has an appropriate length for your choice of gap.
There's probably more power to be gained by trimming the side electrode so it doesn't cover the center electrode; and indexing the side electrode so it's out of the way of the main part of the chamber than playing with the gap itself.
This is an older thread, you may not receive a response, and could
be reviving an old thread. Please consider creating a new thread.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!