bent tops of spark plugs

[binzer]

Looking for help, i have a 1995 formula 583 z, the bottom and top end are new rebuilt, which is a dog to pull and start, it takes to people to start it, i have put on 250 km since done and i am having problems, I went for a ride and it was running good after about a 100 km it back fired a couple time and wouldn't start again. The plugs were bent on the top, i put new plugs in it and it wouldn't start, i waited for an hour tried and it started so i just parked it. The next day i went out to start it and it wouldn't start, again i waited a couple hours tried it and it went, i brought to my mechanic and after 25 km it back fired and bent the plugs again. My mechanic is baffled and doesn't know why this is happening. After a couple of weeks i thought i would take it for a ride and again this happened. any ideas of what is causing this to happen. the bottom of the spark plugs gap and colour is good. Thanks

 

[BBP]

Broken motor mounts allowing the motor to raise & hit the hood?

 

[binzer]

The motor mounts are good, it is bending the top of the plugs where the attach to the caps, this would usually only happens if you flip the sled and it ran upside down, i am thinking it is electrical but not sure where to start

 

[nuttyn01]

Is this a double post? I posted on another one that its due to detonation. It hammers the plug and it basically drives the center up through the ceramic on the plug and this will break the ceramic/porcelain on the plug. Take the engine down for inspection.

 

[clamlake600]

Did you time the rotary valve correctly? Solid tip cap or screw on spark plugs? Crankshaft could be out of true, rotary gear could have let loose...ck with a tdc gauge and look for brass shavings in your oil lines that circulate to tank.