HELP!!! New rebuild won't crank anymore

[Challenger]

I had the retainers come off on my motorcycle and we got it running but it ran terrible. The retainers still held the valve but at TDC the cam was pushing on the top of the valve spring cap.

 

What is the second ring on the surface of the piston?

[zeiss150]

Thats a major problem!!!!! I know the engine only turned over for about 5 to 10 seconds but with that valve smacking into the piston you need to make sure that there was no damage to the rod and bareings. Also that valve snaping might have damaged the valve guide and just because you don't have enough to worry about make sure none of the other pistons made contact with the other valves.

 

If I remember correctly the #1 piston is up at the same time as the #6 piston

 

don't feel bad, i rebuild a KZ100 police motorcycle and I kept bending valves cause I didn't know what that "pop" sound was when I turned the cam with the head laying on a metal bench. I ben't 2 valves before I figured out what it was :stupid:

 

Tear it all apart and rebuild it from the ground up... that way when you crank it again there is no doubt that its perfect!!!

 

Good luck!

Matt-

 

 

Mopar, I think that ring is there to "squeeze" the combustion into the chamber, I think but I could be wrong.

[Challenger]

I meant circle not ring. In the picture there is a circle on the top of the piston. Im not sure what you meant when you said-

"I think that ring is there to "squeeze" the combustion into the chamber."

[OlderThanMe]

Mike, sorry to hear about all of the trouble.

Pull-a-part still has that 80 280zx and they also have a 71 240...if you want one of those...Their price is like $120 for a 6 cylinder engine...

[2003z]

I meant circle not ring. In the picture there is a circle on the top of the piston. Im not sure what you meant when you said-

"I think that ring is there to "squeeze" the combustion into the chamber."

They are Nissan Motorsports Euro "Flat Top" pistons. The ring is a slight dome to raise compression. Funny thing is, they were actually about $3-4 less per piston than US Flat tops.

 

I've got a new piston and intake valve on order (Nissan has 4 left in the US), but there are no exhaust valves available.

 

As for a complete rebuild of the head, I don't think it probably needs it, but I'm taking it to Eddie Radatz at Radatz Motorsports and letting him check the whole thing over and fix it. I'll fix the bottom end.