Wiped a Cam Lobe. Total rebuild??

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Thanatos340

Thanatos340

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Looking for general opinions here. I have a 340 that was completely rebuilt about 14 years ago however the car sat in storage for 12 of those years and the engine probably only has about 500 miles at most.

I got the engine back out towards the end of last year and got it going again. Runs strong sounded great. A couple months after getting it going again and dropping it in my Duster, a Lifter failed and wiped a lobe off the cam.

Pulled the engine, Tore it down. A good bit of sparkle in the oil from the wiped lobe. Now I have torn down to block and rotating assembly. Everything looks good. Trying to decide if I just clean it out, replace oil pump and pick-up and reassemble with the new cam, lifters (Will be installing new heads and intake as well since I have them).. or go ahead and pull the rotating assembly to re-ring and replace all bearings?

What would you do?
 
I would pull the rotating assembly and replace the bearings and rings. Inspect the crank to make sure there are no grooves. Make sure you clean the oil passages thoroughly. You'll be able to sleep at night ;)
 
If you have it out and apart, refresh it. Rings, bearings, etc. Mancini has a good deal on a refresh kit with main & rod bearings, rings, and gaskets.

Cast iron rings:

http://chucker54.stores.yahoo.net/sealedpowerkit.html


Moly rings:

http://chucker54.stores.yahoo.net/sealpowkitb.html



I would also recommend cleaning out your oil passages to make sure there is no debris in there from when the lobe wiped out. At least pull the oil galley plugs and take it to a high pressure do it yourself car wash and blast all of the oil passages. (If you're not soaking wet when you finish, you didn't do it right. LOL!)
 
The metal is everywhere. It needs to come apart, get cleaned out and have fresh bearings and rings installed.

Oil pump and timing chain are two more things I would add.

(Although I have seen friends, back in the day, just replace the cam and lifters, change the oil and go... )
 
Piston skirts usually get stuff mashed into them when a cam lets go.
 
If you want to be sure, you gotta pull the bottom end apart; anything else is rolling the dice; "Do you feel lucky today ?!?". It's 99% likely to be metal bits in most or all the passages, like in the block and yes, inside the crank passages, an maybe even in piston oiling holes. All oil gallery plugs should come out and everthing meticulously scrubbed. That future engine destroying particle could be lurking anywhere.
 
I guess I'm just lucky. Put in a used cam that didn't have the lifters marked. A lobe went flat. I cleaned out the pan, changed the oil and had no problems with that race motor. It was many years ago so I think that ignorance was bliss. I would never do that again
 
compare what new bearings and rings cost as compared to a total rebuild and you should have your answer!
 
crackedback said:
Piston skirts usually get stuff mashed into them when a cam lets go.
Click to expand...

What he said here, I had the same thing happen and when I pulled the rotating assembly I ended up having to polish the pistons to remove the remnants of the cam!
 
If you don't do it right now, you may end up having to do it all over later....


Your choice.
 
Thanks for all the responses. It was what I needed to hear (Not necessarily what I wanted to hear though). It will be a total rebuild.

Also spent the day checking things out the engine on stand and discovered another problem I was unaware of. I was checking the Piston Height since I will be going with new Aluminum closed chamber heads when it goes back together and it seems my Crank was not ground correctly when this engine was rebuilt all those years ago.

Cylinders 1 & 2 - +0.009
Cylinders 3 & 4 - +0.018
Cylinders 5 & 6 - +0.018
Cylinders 7 & 8 - +0.023

When the engine was rebuilt we had a local machine shop turn the crank .010/.020. Not sure how well things were checked when the engine was assembled back then. At least I think it is a crank issue as it is the same for each side of the engine.

If I got to pull the crank and there are issues with it, Looks like I will be shopping for a Stoker Kit. Anyone in the market for a slightly used Kidney, I got one I really need to sell to fund this little screw up.
 
Thanatos340 said:
Thanks for all the responses. It was what I needed to hear (Not necessarily what I wanted to hear though). It will be a total rebuild.

Also spent the day checking things out the engine on stand and discovered another problem I was unaware of. I was checking the Piston Height since I will be going with new Aluminum closed chamber heads when it goes back together and it seems my Crank was not ground correctly when this engine was rebuilt all those years ago.

Cylinders 1 & 2 - +0.009
Cylinders 3 & 4 - +0.018
Cylinders 5 & 6 - +0.018
Cylinders 7 & 8 - +0.023

When the engine was rebuilt we had a local machine shop turn the crank .010/.020. Not sure how well things were checked when the engine was assembled back then. At least I think it is a crank issue as it is the same for each side of the engine.

If I got to pull the crank and there are issues with it, Looks like I will be shopping for a Stoker Kit. Anyone in the market for a slightly used Kidney, I got one I really need to sell to fund this little screw up.
Click to expand...

Since those number slope the same direction all the way along the deck, I'd question how true the deck is before the crank being ground wrong.
 
Complete rebuild. Nuff said.
 
Regardless if you decide to change bearings or not, (which would always be a good thing);
for the folks saying there are now metal particles in the oilpassages, you're also at the same time saying the oilfilter doesn't do it's job at all then. How else would it get there?

I wonder how you all can sleep at night knowing the oilfilter is there just for show...
Or is it? ;)

In any case, at least change the oilpump for a new one, as this is the part that sees the most wear in such cases.
 
He has metallic particles in the engine. The oil has to drain into the oil pan after being SLUNG ALL OVER GOD'S CREATION off the camshaft and reciprocating assembly. Metallic particles are everywhere. What I have to wonder is how you could not know that.
 
crackedback said:
Piston skirts usually get stuff mashed into them when a cam lets go.
Click to expand...

X2, when my old motor wiped a lobe my pistons got metal stuck in the piston skirts...now there're junk. I just started over and rebuilt the whole thing, new oil pump, pistons, bearings, rings, etc.
 
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