What could cause this

[2CrX]

The seating area for the valves was all stock, no headwork done. He said that he hadent pushed it at all that night.

[91civichatch2571]

Did he have stock valve springs? If he had aftermarket valve springs, but stock valves, this is what could've happened. With new stiffer valve springs, when the valve is closing, theres a lot more force from the new spring pulling the valve back to its seat. It pulls it back so hard and so fast that some stock valves cant handle it and the head will break right off of the stem and drop into the cumbustion area.

[1PhatCX]

Originally Posted by 91civichatch2571

Did he have stock valve springs? If he had aftermarket valve springs, but stock valves, this is what could've happened. With new stiffer valve springs, when the valve is closing, theres a lot more force from the new spring pulling the valve back to its seat. It pulls it back so hard and so fast that some stock valves cant handle it and the head will break right off of the stem and drop into the cumbustion area.

i agree with this statement, he might have been running really lean too or it was pre-igniting badly causing everything to melt down first. look at the cat (if he has one) and see if theres any metal in there that got collected because it would get collected in there because of the screen material.
hurry and get pics of everything

[Gohan Ryu]

Originally Posted by 91civichatch2571

Did he have stock valve springs? If he had aftermarket valve springs, but stock valves, this is what could've happened.

Please tell me he wasn't using a stock valve train with 11.5:1 pistons...that's nuts. Guessing from that picture, it wasn't weak valves anyway. It wouldn't cause that much damage - especially to the spark plug.

The lowest octane rating recommended for 11.5:1 pistons I've seen is 95...93 might have worked but you're friend was pushing it...

look at this link and see if any of the pictures look like your friends piston.

http://www.hastingsmfg.com/Service%2...reignition.htm

[2CrX]

No they dont look like it, His was way more fuked up. Almost the entire center of the piston was gone. I will hopefully get pics up soon. Dont have digital camera so i have to get them developed.

[D16z6-T]

i would say clearence problem also