spark plug issue

[lane912]

so i have a engine that i did not build but is new and was built buy a reputable person but it is having a issue with the spark plugs. the piston is touching the spark plug just enough to squish the gap on the three and the four, the one and the two don't have this problem. i am using Bosch super+, is there a spacer that would gain me the couple thousandths i need or is there a different plug that doesn't protrude as much like the platinum 4. i am also thinking that this is due to carbon build up as there were numerous exhaust leaks that i have found and taken care of.

[lane912]

oh, this is in a 1600 with mc pistons..... and the compression is all within 5%

[Tom Oxner]

Could you just double the washers under those plugs. Most of the hot rod shops sell these washers to index spark plugs. Good luck.

Tom

[maybe368]

How long ago was the engine rebuilt? I am not an expert on Porsche engines, but I believe 1 of the tests on assembly is to check these clearences with clay and to appropriately shim the cylinder barrels. When did this problem pesent itself? After running the car? You could always buy a set of new plugs and use the spacer/washers off those ane save the plugs for later use...Mark

[djdsc]

Folks often use an extended tip plug in these cars like the NGK BP6HS. I believe that the "P" stands for the extended tip. Try the NGK B6HS, it is the same heat range but not extended tip.