Lost a Motor last night.

Originally Posted by MCCUTCHEON4

Jeff, I have tried to attach a picture of the motor here.

Wow, that's a valve clearance issue. I would ask what the exhaust valve to piston clearance was when assembled. The "New" pistons definiatly need to be flycut or a smaller cam "Exhaust Lift" needs to be installed.
If the P/V clearance was greater than .100 then your the springs pressures need to be increased, but since you said thier around 200+ seat pressure then I don't think that is an issue.
This is just me, but I think your exhaust lift is to large for the configuration you have.

A shot in the dark could also be the P/V clearance is to tight and the cam is advanced or retarded to far.

I would take it back and have a discussion with the builder.

Greg,
Some one just sent me this.... Guess it proves as you know Murphy's Law is alive and well.. We should have our 408C back together next week.

Jeff

Well any updates? Is Bliss rebuilding it or what?

Pete

Originally Posted by 351bolt

Well any updates? Is Bliss rebuilding it or what?

Pete

Taking our time. Still at the machine shop, got to sleeve number 8. We're taking the opportunity to put in some more ponies. New roller and some CNC heads, matched intake. Calculator says ¾ second improvement, should be low 10’s maybe tap a 9. Building a class legal NHRA super street on 10” tires. No laughing gas for us…….

Originally Posted by 351bolt

Well any updates? Is Bliss rebuilding it or what?

Pete

Hey Pete,
Brooke and I took it out to Dave's on Saturday, Dave is going to try to figure why it broke and we wil go from there. We did run the car over to get a cage installed today, so there is some forward progress.



I am going through one of those purging times..... I have around eight rigs I'm going to off. I will keep the hulk truck, 3-Harleys and this Mustang project. Its time to suck up to Wife for a while.


Did you get the four popper figured out?

Gregg

Just a thought. If the cam pin sheered and the cam started lagging behind, it would make sence why multiple exaust valves hit.
Good luck
Rick

I actually hope we find an explanation like a broken cam pin or similar problem
that will explain the failure. If we had been runnig the motor for a season or two I would not feel so bad about the motor blowing up, but two failures in only five passes is not acceptable.

I have wondered if we wound it to tight, but really doubt it. I had a 7000 rpm
chip in the MSD, and the only time it hit that was while doing a burn out.
My son was shifting at 6800 rpms.

Ya I got the 4 cyl figured out. Bad head, burned valve, cracks. Just got the rebuilt yesterday, hopefully get it running this weekend.

Who built your cage? Custom or kit?

Pete

Did anyone not notice in the one picture that the number two piston was turned in the bore?

Telltale sign of bottom end failure--rod or crank.

If it was the crank, the back part is still spinning, front part is "out of time" and valves hit the pistons. Or, like the last one I did, it broke in 3 places. I pulled a head at the track, thought it might be easy fix (maybe a valve). I saw one piston turned in the bore. I stopped there. Then I noticed that two pistons on one side were at top dead center (or close). Two pistons at TDC or near TDC on the same bank--that means problems.

Man, I hate to see engine failures like that! IF there is anything good that comes out of busting parts, you learn what not to do next time. You're lucky....some of us have broken stuff and oiled our own tires, at the very least gotten out of shape and some of us have not been THAT lucky.

Good luck and please keep us updated.

Originally Posted by mavman

Did anyone not notice in the one picture that the number two piston was turned in the bore?

Telltale sign of bottom end failure--rod or crank.

.

We all must be BLIND...!!! Good catch.... I think we were all looking at the exhaust valve impacts and not looking at the piston orientation.

But, what happned first the valve hitting the piston causing the rod / crank to break, or the other way around?

Hard to tell in the photo if there are any valve impacts on Piston number one. It is too dark, but it looks clean. If there is....then:

If the crank was broken first, then the vavle impacts would only be after the crank break, and not on both sides of it... Is this correct? The front part of the crank that is not broke should still be in tune with the timing of the valves.... and not show any valve impacts....right? Unless the chain broke because of the crank break....

Maybe the OP can clear this up for us... Did the OP notice the twisted piston?