Topic: spark plugs hitting pistons

[zollcat]

Has anyone had trouble with spark plugs hitting pistons?  I have a 836 with copper base gasket and my head has been surfaced giving me more compression (bought the engine this way) However after assembly and trial starts I found that the grounds on the plugs were smashed into the electrodes and scratches on the top of the pistons where they hit the spark plugs. Are there any suggestions for fixing this issue.  I thought of cutting off the grounds and making side fire plugs but I cannot get the gaps accurately the same. I could use thicker gaskets but then loose compression.  Any other Ideas out there.  thanks for your help ~Casey

[mlinder]

Shorter plugs?

[754]

Extra or made up washers will do the trick.
 I had a set that hit, had a big bore that was made outa 350 pistons, someone back in the day came out with a new "Great ZOT Super-Duper" plug design that was supposed to be the best thing... Hit the piston on every one...

[Terry in Australia]

Yeah mate, like Frank suggests, get someone to machine you up some soft alloy or copper (for sealing quality) spacers to go under your spark plugs, between the plug and the head. 3-4mm should be fine. Cheers, Terry.

[BLUE71TURBO]

What spark plugs are ya using ?   

[lordmoonpie]

Same issue on my bomber - it's close up the spark gap. Solution was to use another plug's crush washer so each of mine had two washers, all sorted.

[MRieck]

 I use Kawasaki part # 11009-1376   Copper "gasket" 12.4 X 17X 1.5

[bucky katt]

Extra or made up washers will do the trick.
 I had a set that hit, had a big bore that was made outa 350 pistons, someone back in the day came out with a new "Great ZOT Super-Duper" plug design that was supposed to be the best thing... Hit the piston on every one...

that 350 twin pistons?

[754]

A lot of early big bore kits were made of 350- 350 +1mm pistons, if they didn't cut down the crowns, you ended up with pretty high compression ratio... & very little plug to piston clearance...