Read this thread for back story:

(cliff notes: lifters spun in bore after rockers came loose.. I think...)

http://web.camaross.com/forums/showthread.php?t=438130

Tested compression on #3, nice and healthy.

Compression on #6: 0 psi

Finger test on the plug hole of any cylinder blows your finger off the hole, #6 barely pushes out any air.

Not sure what the diagnosis is going to be, holed piston? Bent valve?

My buddy wants me to start pulling the engine w/ him tomorrow. I might, we'll see.

 

On the original post I had a suspicion there was going to be something else ya was going to find.

 

If it's coming out thru a valve you can crank it with the ign disabled and listen for it in the intake (with the TB open) or tailpipe. If it runs, you can put a vacuum gauge on there and see if a valve is staying open, although if you made a hole in a piston, that will cause a pulse too. I think you might have pounded a valve.

 

Here's a happy piston picture from work. This was on a small engine.

 

Ya rattled that one,once to often.

 

Put a cylinder leakdown tester on it like I said from day one. That way you can pressurize the cylinder, and listen to find out where the air is escaping.

Did you assemble the valvetrain with that bad cam? If the intake lobe is worn, it may not be letting any air in there.

 

Yah I threw two old lifters on it and popped the valvetrain back on. Cam isn't that worn out, it's got plenty of up and down travel as far as valvetrain movement is concerned.

There's so much metal in the oil chasing after this anymore is pointless.

Engine is coming out for teardown.

She will live once again.. in 355 glory.

 

Didn't get one of the rockers too tight did you?? That would bleed the compression off.

 

 

 

Diagnosis:

#6 piston slapped the exhaust valve

Can you guys help me diagnosis this in anyway? I wouldn't have thought a rocker coming loose would have caused the exhaust valve to drop that far. Could it have been caused by an overrev due to my slipping tranny?

I'm confused now...

Anyways.. Eric, got your PM, if I a deal i have going on with a board member doesn't go through for some reason I'll contact ya, thanks!

Bent my #6 exhaust valve too.. DAMNIT.

 

At 6000 rpm, a loose, lifter, pushrod, rocker will pound itself silly - it's all out of control at that point worse than just valve float. Just imagine it bouncing in there at 100 times a second all loosey-goosey and you can kind of get the picture. Say the lobe is coming around and the lifter isn't back down yet - it slams the lifter back up and that shudders thru the valve train and smacks the valve all at the wrong time - valve hits piston, everyone loses but the machine shop and the parts dealer.

Actually, we experiment with it at work and watch it through a strobe light or high speed camera. It's amazing what you see. Sometimes we destroy engines on purpose by running them flat out in a steel box until they explode or let out a death wail and screech to a halt. We only make up to 1000 cc, but it's still more fun than anyone should be allowed to have at work

 

Thanks Kevin, should I replace the two springs on that cylinder?

I'm not sure what happens to the strength of a spring when it goes to coil bind.

 

The machine shop could probably test them out for you and see if they'r OK. Coil bind is bad for them, though cause there's no more give in the usual direction.