Why did my cam walk forward?

[Tatsadasayago]

By the way...

Nice rod carnage

This is what my 401 did at 55 MPH one Easter Sunday...

[Nikkormat]

I'd post pictures of the other rod and pistons associated with said rods... But they look allot like sand. Just made of aluminum and forged steel!

[Nikkormat]

What did that 401 in?

[Tatsadasayago]

Chewed up timing gears got into the oil pump and jammed it causing oil pressure loss. Happened so fast I wasn't aware of a problem until the Cherokee bucked and there was an expensive crunching sound. It was epic!
My girlfriends son's asked me: "Jim, what was that?"
"Dunno Steven, but it sounds expensive."
The Highway Patrol cop that was tailgating me got a grille and windshield full of shrapnel, oil and coolant. He was cool and gave us a ride into town though.

[Nikkormat]

Ha! Now we just need bumper stickers that say... Warning - Excessive risk of shrapnel. Stay back 100ft

[carnuck]

Cam retention plate is the only way to go. Sounds like the front cam bearings were worn or installed wrong. Hydraulic pressure behind the cam will start it forward but improperly ground cam rams it out fast!

[Nikkormat]

Doing new can berings wouldn't a guy need to take out the rear freeze plug? Hmmm... Than wouldn't it seem odd if the new one was the same brand places in exactly the same orientation with exactly the same red and blue paint flecks? That builder and I might have more than just the cam walk to talk about.

Here are bultears causes of cam walk:

8. Cam walk: Cam walk can be attributed to a cocked or poorly place cam plug (large freeze plug that hold the cam from leaving the rear of the block. Also cam walk can be caused by bad lifters, worn cam bearings, cam bearings installed improperly, or a poorly ground cam and in some cases a new cam that gets flattened on startup

9. Cam walk can also be attributed to lack of relief holes in the back of the cam, you see pressure can increase between the end of cam and cam plug, most of these cam must be checked, we have 3 in here with no relief holes...............dang summit

[Nikkormat]

Calling the builder today. What other advice can you offer?

[will e]

I think you were smart to not dig into it. Let him be there when it is taken apart. Make sure you are there too.

[Nikkormat]

He wants me to pull it and bring it down so he can dig into it himself. He's pretty saying much f you on the labor at this point but we'll see what kind of tune he's singing after the shop gets done chewing him out.

He said that it's "awfully peculiar" that this much damage would happen in so little time. Let's hope he does the right thing and fixes his mistake. Wether that was not checking the cam before installation or sinking that freeze plug too deep.

[serehill]

It does sound like the best thing to let him tear it down. I would doubt the freeze plug. The timing chain would have been dead give away. I am surprised the timing chain if its any good at all would walk that far.

Please let us know what it was.

[will e]

Mistakes happen. I hope he is stand up about it.

I had an engine guy rebuild a 3.7 power tech for me. He is really more into the old iron and is know for his abilities on really old and more rare engines. (Like a Packard for example). He didn't know (nor did I at the time) that the 3.7's have propensity for dropping intake valve seats. So he didn't replace them. Sure enough, the darn motor dropped one not more than a couple of months after the rebuild. I pulled the head and he replaced all of the seats, replaced the valve, bought new head bolts and all of the gaskets I would need.

[Nikkormat]

Update: Over on the AMC Forum we've had a break through thought. What if the cam bolt backed out and caused the damage not the cam itself? That would explain that lack of distributor problems and the amount of deflection in the cover! So tomorrow I'm going to pull the distributor and use a boreoscope to check if this is the case.

Has this happned to anyone else? I'm really hoping its just this so I can drop the pan remove the cover and be done with this mess.

[jaber]

You dont have to drop the pan...

[serehill]

Anything is possible.

[Stuka]

You dont have to drop the pan...

He will to pull out any pieces of the cover that went into the sump.

[carnuck]

Won't need a borescope either. Should be able to see with a flashlight.

[SJTD]

Update: Over on the AMC Forum we've had a break through thought. What if the cam bolt backed out and caused the damage not the cam itself? That would explain that lack of distributor problems and the amount of deflection in the cover!

This was sorta proposed early on in this thread, fourth post.

[Cheap Hobby]

Have you got the engine back to the builder yet?

[serehill]

Really don't understand the point the engine builder has made it pretty clear if you mess with it disassemble it you may likely void the warrantee. That's why he said leave the pan on it. this is headed for the next catastrophe. Why don't you ;et the mechanic do his thing he put the cam & the cover together didn't he?? If he's telling you to leave it alone don't dismantle it I wouldn't touch it.
Your epiphany may or may not be true. The cam bolt sounds logical. Are you wanting to find out so bad you would void the warrantee?