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General Tech Engine Rebuild: Failed at Cam Break-in

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KVH

KVH

Obi Wan
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Back in 2005 I rebuilt my engine. I was "green," and failed to run a break-in procedure for the camshaft. Here are two pics of the damage 15,000 miles later. Do I trash the cam? Advice on break-in? I think I was told not too long ago to run the engine for 30 minutes at 2700 RPMs with cam lube slathered on the shaft and tappets. That simple?

Ouch Cam 1.JPG
Ouch Cam 3.JPG
 
OUCH! Yeah, afraid so. Funny that until fairly recently I'd never heard of breaking in or bedding a cam. But apparently that's standard operating procedure. (But then I'm not or ever was a professional mechanic...)

Anyway, cam lube and 2000 rpm for twenty minutes is the recipe I've been told. And to follow, use oil containing zinc for continued protection.

You might be able to have the cam reground; check with a reputable machine shop, or contact someone like Crower: https://www.crower.com/media/pdf/regrinds.pdf

Mickey
 
Mickey Richaud said:
OUCH! Yeah, afraid so. Funny that until fairly recently I'd never heard of breaking in or bedding a cam. But apparently that's standard operating procedure. (But then I'm not or ever was a professional mechanic...)

Anyway, cam lube and 2000 rpm for twenty minutes is the recipe I've been told. And to follow, use oil containing zinc for continued protection.

You might be able to have the cam reground; check with a reputable machine shop, or contact someone like Crower: https://www.crower.com/media/pdf/regrinds.pdf

Mickey
Click to expand...
Good info...APT and Delta regrind as well, but APT hardens their cams after the process. Make sure you get a cam and lifters with a similar hardness so one won't eat the other and I like to use the thick APT cam break in lube. Follow Mickeys advice on break in procedure and if you want to go the extra mile you can buy a high zinc oil made for that purpose.
Rut
 
Remember new cam needs new lifters.
 
Always trial fit the lifters to the block before the cam is installed so you can verify that they slide easily in their bores with only a light machine oil .
 
I'll likely buy a new cam from Moss or BPNW unless one of you feels strongly about another source. I don't want a performance can.
 
Whatever Cam you buy make sure it's properly hardened! Same thing with the lifters.
Rut
 
I am no pro either, I would get a different cam may be yours is bent or twisted or whatever. But again could that damage be from a valve adjustment or bent push rod or some there. I would go stock and try and find one from an old tr motor that I knew, but getting a new one from China might be ok they are starting to produces useable stuff these days sometimes.
steve
 
Rut said:
Whatever Cam you buy make sure it's properly hardened! Same thing with the lifters.
Rut
Click to expand...
Second that. You might also try one of the camshaft specialists who rebuild old cams. I think the best of them at least have hardening capabilities.
Tom
 
I used to build engines with 600+ pounds of open valve force. Those had to be meticulously broken in, or you would flatten the cam in a matter of minutes. On our little stock Triumph engines, I can actually push the valves by hand, so they are very easy on cams.

My belief is that you didn't do anything wrong. For our stock springs to hurt your cam, either the cam or the lifters were not properly hardened. Especially if you got so many miles from it! Honestly, a break in problem manifests in minutes, and you get glitter in your oil from the metal that flies everywhere.

As for which cam to buy? A year ago I would say any of our "Big 3" suppliers. Unfortunately, this last week I have had a rash of really badly manufactured new parts from ALL of the suppliers. They all have their issues, and get batches of low quality parts, not necessarily their fault...but we all bear the brunt. I have never heard of a bad cam coming from Crower, Comp Cams, or Isky Cams. If you live in a big city, there are very good grinding services, that will do it right and makes sure the cam and lifters are properly faced and hardened.

On a note...since your cam has a bad lobe and there is doubt about it's hardness, I would not re-use it, even for a re-grind.
 
I realize that this is not my area of expertise--but that kind of pitting does not strike me as wear, which usually shows up as scoring. Pitting is usually corrosion from some other cause. I'm surprised that there is no ordinary wear on the heel of the cam; after 15K miles, I'd expect something.

As for break-in lube, Hap Waldrop, a respected engine builder who hangs out in the Spridget forum, recommends molybdenum disulphide assembly lube. But remember, whatever you use, it lasts only a few seconds, until the engine gets going. So the break-in oil is probably most important.

The business about ZDP has been pretty seriously overstated by repetition. I'd make sure there is decent amount in the break-in oil, but not over 0.14% Zn, and replace it with some ordinary oil at the first change. Too much can cause corrosion, not unlike what I see in your pictures.
 
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