Plugs and Gaps

Maverick · Post by **Maverick** » Mon Dec 07, 2009 4:18 pm

Some of you might find this thread in the Maverick Forum interesting. http://mmb.maverick.to/showthread.php?t=62386

Fred32v · Post by **Fred32v** » Mon Dec 07, 2009 11:16 pm

Plugs are pre-gapped and you only just check to make sure they were not damaged in transit. However, Hutter Automotive has GMJohnny gapping his plugs tighter than the stock recommendation on his Vette and his Supercharged Regal. I don't know the exact numbers, but I thing the Regal GS went from something like .060 to .045 and GM really liked the results. I not sure exactly why, maybe GMJohnny could expand on this.

markss327 · Post by **markss327** » Tue Dec 08, 2009 7:55 am

It's my understanding, the more cylinder psi, (via hi compression, boost, or lots of ignition advance) the closer the gap should be.

Maverick · Post by **Maverick** » Tue Dec 08, 2009 3:31 pm

I liked this comment by the expert

Large plug gaps came into vogue with car makers in the late 70's and early 80's. The thinking is that the larger flame kernal would help get better emissions. Most automakers now use .030 to .040 gaps today. Even the LS series engines went to .040 after initally calling for a .060 gap. Large gaps tend to "blow out" the spark under high compression and boost. In any high perfoamnce engine, you should run the biggest gap you can that does not cause mis fires under load. From personal experience with ford performance engines, boosted engines run best around .025-.030 and high compression engines run best around .030 to .035