Piston Hitting Spark Plug

[Sam_Q]

thats interesting, although in the case of a 4agze it would be part of the top ring land/crown because the crown isnt raised in the center only the edges of the piston is. However this is only on the big port... so Jason is this a bigport or a smallport? detonation damage in theory could knock out a peice of the ring land and get jammed in the lowest part of the piston which is the center afterall

[drc_ke20]

check the thread depth where the spark plug is screws on and compare with 2,3 or 4 cylinders it could be badly scored?

[Sam_Q]

it would have to go down like whole depth of the combustion chamber and the dish of the piston, so I think we can rule the head and the spark plug out of things unless almost all the thread is gone in the head to the point of having a big enough hole for not only the widest part of the plug to fit down but also the socket driving it, but even in this crazy scenerio a spacer wouldnt of worked as it has.

 

I have to say this is quite the brain teaser.

Edited April 19, 2009 by Sam_Q

[Sam_Q]

I don't want to be the bearer of bad news but I will take my guesses at it being internal engine failure or a foreign body. I can't see it being the later as it would not get past the supercharger? but hey I could of overlooked something simple which will make me look quite the fool.

[Jason]

Ill get pictures this afternoon, I wouldn't put engine failure that far away it is the first motor Ive built :jamie:

By looking at the piston through the spark plug hole there is no damged to the surface, ive checked for any foreign bodys. Hopefully within the next two weeks i can get it back on an engine stand and see wtf is wrong.

 

Detonation damage would be a relief but I somehow doubt it with how rich I'm running it at the moment.

[towe001]

I'd place a long screw driver or something down both number one and number four spark plug holes while the pistons are just before TDC and spin the motor over and see what happens.... By rights both pistons should go down at the same time, if No.1 lags behind there's something loose down stairs or if there's very little downwards movement its a piston problem....

 

But as Sam said

show us a pic of the plug

With the other good ones

But normally you'd hear noises coming from the motor if somethings loose, so it could even be a high carbon build-up since your running a rich motor

[Teddy]

Thats a very good point, he is running it so rich that the air fuel ratios are almost the other way around :P

 

lol

[Sam_Q]

I was thinking along the lines of something had come unstuck and now is lodged into the center of the piston, hence no sound. Its a long shot though

[Jason]

Bo rowing medicine_mans (thanks justin :P ) engine crane so ill soon find out whats going on.

Edited April 21, 2009 by Jason

[Jason]

TEDDY POSTING HERE ;)

 

Results are as follows.

 

lol.

 

:)

[KE30_KE35_KE55]

TEDDY POSTING HERE ;)

 

Results are as follows.

 

lol.

 

:)

 

I'm amazed that got past the valves, are the valves OK?

[Jason]

she needs a new head on closer inspection.

 

ted

[tact_ref]

fantastic thread. pity about the damage though.

[towe001]

Holly crap, i guess it wasn't carbon build-up thats for sure

 

 

 

Unless it also comes in a gold colouring

[Jason]

Valves are fine valve seats on the other hand.... the exhaust one look scuffed. Will take valves out and have a closer look tomorrow. Hopeing a pollish clean up will show i don't need a new head, I carnt afford one at the moment.

 

If any one was wondering what it was, it is a rubber seated washer for the valve covers, managed to get sucked up in there when i was testing with the manifold wide open :)

 

 

Weird thing is I never saw it when i was poking around through the spark plug hole.

Edited April 25, 2009 by Jason