Thread:

Carnage Pics

So I went down to the machine shop today. They got the heads off and as expected #8 piston is done. Cylinder didn't look too bad aside from a couple of minor dings that can probably be machined out.

The #8 exhaust valve broke while the motor was running. As to why it broke we don't yet know. He hadn't yet gotten the rotating assembly out yet so hopefully I'll hear from him tomorrow and have more answers.

The one thing we do know is that for some reason cylinders 1, 3 and 5 have marks on them that suggest the intake valve face contacting the tops of the pistons slightly...as if to stamp their imprint through the carbon layer on the top of the piston. I bought the heads off of eBay so I'm assuming they didn't come off of the same motor and one of them may very well have been milled at some point in its life. Another possibility that someone else mentioned is that the timing gear crank key may have sheared and started this whole mess.

Anyway...here are the pics.

Damaged #8 piston with exhaust valve head sitting on top of it




If you look at the color of the top of the piston you can see that the fuel mixture looks damn near perfect, and the carb is bone stock.

So then the cam didnt break like you had said? It looks like a hydrolic flat tappit cam? I/We have heard the motor on the rev limiter a few time while blasting turns. Valve float with dome pistons? could also explain the eyebrows in the other holes. Hope you can get it done during the winter and be ready for spring runs.. Sorry about the carnage and good luck. Keep us posted onteh rebuild and upgrades cause we know you cant leave well enough alone...

Originally Posted by Hullshot

So then the cam didnt break like you had said? It looks like a hydrolic flat tappit cam? I/We have heard the motor on the rev limiter a few time while blasting turns. Valve float with dome pistons? could also explain the eyebrows in the other holes. Hope you can get it done during the winter and be ready for spring runs.. Sorry about the carnage and good luck. Keep us posted onteh rebuild and upgrades cause we know you cant leave well enough alone...

Yes the cam did break. We just didn't know why until now. Our theory on why the cam broke is that the #8 exhaust valve broke, which caused the spring to relax against the rocker, which jammed the lifter into the cam and bound it up, causing it to break. As to why the exhaust valve broke...by looking at things I couldn't figure out why it had. Could've been a bad valve from the start.

Another possibility is that the crank key on the timing gear may have sheared, but he didn't have the timing cover off yet when I went down there to look at things.

In regards to the "eyebrows" on the 1, 3 and 5 pistons...I got these heads off of eBay and don't know if they were ever on the same motor or not. We're thinking that at some point the head was milled down for whatever reason. He's gonna CC the heads to find out. If that's the case we'll have to go with different pistons...which would suck because then I'd be left with 7 perfectly good pistons that I can't really do much with. Or...not

If everything goes as planned I'm hoping to have her back on the water by then end of Febuary. As far as upgrades, I'm just wanting to restore the motor back to the way it ran before it blew, but we all know how that goes.

Originally Posted by Jetaholic

Yes the cam did break. We just didn't know why until now. Our theory on why the cam broke is that the #8 exhaust valve broke, which caused the spring to relax against the rocker, which jammed the lifter into the cam and bound it up, causing it to break. As to why the exhaust valve broke...by looking at things I couldn't figure out why it had. Could've been a bad valve from the start.

Another possibility is that the crank key on the timing gear may have sheared, but he didn't have the timing cover off yet when I went down there to look at things.

In regards to the "eyebrows" on the 1, 3 and 5 pistons...I got these heads off of eBay and don't know if they were ever on the same motor or not. We're thinking that at some point the head was milled down for whatever reason. He's gonna CC the heads to find out. If that's the case we'll have to go with different pistons...which would suck because then I'd be left with 7 perfectly good pistons that I can't really do much with. Or...not

If everything goes as planned I'm hoping to have her back on the water by then end of Febuary. As far as upgrades, I'm just wanting to restore the motor back to the way it ran before it blew, but we all know how that goes.

Typo, right? You meant November didn't you

Originally Posted by Budweiser

Typo, right? You meant November didn't you

No ***** the best part of the boating season for the DLB has just begun son.

thats what im sayin...isnt CP performance close to you whats the cost to rebuild as apposed to just buying a new motor swap everything over and roll out...

We most certainly are right around the corner! We chatted the other day about the motor and what could have caused the carnage, have to wait till the motor is completely apart and most likely will have more answers then. On the rebuild, we can get anything you need so you wouldn't have to pay shipping, just let us know what ya need and if we can help.
Brian

Originally Posted by CP Performance

We most certainly are right around the corner! We chatted the other day about the motor and what could have caused the carnage, have to wait till the motor is completely apart and most likely will have more answers then. On the rebuild, we can get anything you need so you wouldn't have to pay shipping, just let us know what ya need and if we can help.
Brian

Will do Brian. I'll definitely keep you posted seeing as how it seems like I'm in your store like every other day.

Originally Posted by Jetaholic

Will do Brian. I'll definitely keep you posted seeing as how it seems like I'm in your store like every other day.

So you will be ready for NOV 22 then nice!!!!

Originally Posted by DAVEO

So you will be ready for NOV 22 then nice!!!!

Don't I wish. Unfortunately my money schedule is governing this build and as of yet I have no idea what we're looking at in regards to total cost to rebuild.

Originally Posted by Jetaholic

Don't I wish. Unfortunately my money schedule is governing this build and as of yet I have no idea what we're looking at in regards to total cost to rebuild.

So what your saying is your makin' it Nov. 22nd.

is that a cheby mota or a furd mota?

Sometimes when you back off and the intake goes in a more vacuum mode, parts tend to migrate to other parts of the engine, when it's still running.
Plus, with an intake valve out, you have pressure from the compression stroke (Yeah, I said stroke ) pumping part numbers to other parts of the intake.
Hope to see you back on the water soon

Originally Posted by 707DOG

is that a cheby mota or a furd mota?

Tony, have you not noticed my sig line pic? Of course it's a chebby.

Phil, Sit N' Spin won't be makin' it but one way or another I will be.