Rob94hawk

I have semi-hemi heads on my 4.7L truck and I cut the electrode back and gapped them to the side to unshroud the spark from the fuel mixture. It seems that I lost some mpg by doing this. The gap is the same so I can't see how mpg would change. I would think fuel mileage would increase. Any insight on this? Thanx, Rob

Zero_to_69

Exposing the spark to the chamber is the best thing you can do,
however I don't know that modifying a plug is the best method.

I have seen plugs out of blown alcohol motors that are fabricated
as you describe.

As for the drop in fuel economy, the only thing I can think of is the
surface area of the electrodes has been reduced and may be
causing a misfire because of excessive heat on the nose of the
spark plug.

Just a guess, but I'd think you compromised an important aspect
of the plug by cutting back the electrode?

Damon

Been there, done that! Side-gapping the plugs probably didn't help or hurt very much. However, the plugs "go away" VERY VERY quickly when used on a street-driven engine. I'm talking only a few hundred miles and they already begin to degreade. Not usre exactly why but I've always found it to be true.

lt1form

Sorry, stupid question : could someone explain "side gapping"??