Quote:
Originally Posted by vince1
I wish I hadn't made the comment on the red. Getting used to it now.
I question the need for this cam break in procedure too. It is beyond me why we should have to do that. Don't the manufacturers harden them at all? It seems with new lifters and a new grind that they should run smoothly against each other and why should they wear? What happens to them during the break in that would make them more durable? Why don't the manufacturers run them in?
After seeing a couple of worn out cams I can understand that we have to use the right oil.
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The reason for breaking in flat tappet camshafts goes back 100 years long before oil companies removed zinc/phosphorus from most over the counter oils.
The flat tappet camshaft is made of ductile iron. The lifters are made of tool steel. Dissimilar metals that are spinning on each other. The lifters sit offset on top of the cam lobe and spins on it. Both the cam lobe and the lifter's bottom are not completely flat to allow this to happen. The break in period of 20-30 minutes between 1800-2200 rpm wears these two different metals together. They become matched. The zinc/phosphorus helps keep those two dissimilar metals from wearing. I have heard the zinc is there to take the wear, so the cam and lifters do not.
Why flat tappet cams go flat can be a lot of reasons. All of which can be avoided. Use proper oils with enough zinc. Not letting the engine idle for a long period of time before breaking in cam. Not breaking in the cam. Not priming the oil before firing the engine. Not using cam shaft lube.
On occasion, even doing all these correct, a lifter or cams fail. They are mechanical items and sometimes mechanical things fail.