Our trouble with the cam was from a break in and not a well used engine. We had medium strength valve springs and Rhoads lifters. The spring seat pressure was not that high so we never thought much about it. About the time the car came back, the first of many articals came out about the oils. There was a question about cheap off shore made cam blanks and lifters. We talked with Rhoads and were assured the lifters were good, so that left the cam and oil. The cam grinder also felt confident the cam was good but they had a lot of complaints about them going flat. It seems they were finding out about the oils at the same time everyone else was.
Heres a bit of information they passed along, most cams fail within the first minute or two. If they live through that, they most likely live a long life. Thats why its so important to have everything ready when you first start a new engine. You will wipe off all break in lube with in the first one or two revolutons, so the type of oil really matters now. With out the zinc and other additives, the cam isn't protected like it once was. Ours was most likely a combination of a questionable finish on a cam lobe and the oil. We will never know for sure, but the since we changed to the diesel oil and GM addative, we haven't had any problems, and every one we talk with has seen the same success.
As for your 50 year old engine, I doubt you well ever see a cam go flat with stock 60 to 70 pound valve springs. A good race spring is in the 120 pound seat pressure with over 300 pound at full lift! Rpm also plays a big roll in how the parts wear, and again, your 2500 rpm engine is not going to wear out many parts.
What Oldcarkook and the other writers are tring to get across is that things are changing and you need to be aware of it. It may not effect you now, but in the future it might.
I run 5-30 synthetic oil in my 250 so the Rhoads lifters will bleed down right. The valve springs are not strong enough to hold the lifters open so they work like the are suppose to with standard weight oil. I don't worry about the cam or lifters because I know they are not being over loaded. I did how ever use diesel oil for the break in.
Joe
