Hey guys does any one know if it is possible for a plug to hit the piston and still run OK. And what the proper plug is for a 93 evo

 

Champion RN12YC (404), 38 to 42 gap and no it should not hit

 

If they're the right ones, the plugs will never hit the piston. Not in a million years.

 

Just curious, what makes you say this? Did you hear a noise, or is the ground bent?

 

Have a knock. When search engine with stethascope it seams yo come right from plugs. Its an 93 flh with modified heads and an ss 89 stroker. Just not sure if it has the right plugs. NGK chart says plug that is in it is for an 80 ci.

 

I don't know if the stock plugs fit in an 89, did you pull the plugs and inspect them?

 

Try going one step colder with the plugs. Between the stroker and "modified heads" you probaly have a little more compression than stock and need a slightly colder plug. Hope this helps.

P.S. you might also be picking up some valve noise(valve closing).

John

 

Stethoscope or not, locating a noise is damn near impossible. Could be coming from an exhaust pipe, pushrod, maybe MY pushrods...anywhere.

 

True to noise location but it is the loudest right at the plug. Been all over engine and that seems to be.the.spot. as to inspection yes I did. They look fine but I was told the piston can hit and not damage them it will just make noise. Just seeing what other info I can get. Has NGK bpr5es-11 in it now

 

For test purposes only, put a washer or spacer on the plug so it does not sit so deep in the head and run it again. See if noise stays or goes away. YD