Blown head gasket and worn wrist pin... rebuild advise?
#22
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BUT, I've always run a high zinc oil and broken cams in.
#23
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Bought my first car at 16. It had a 390 w/428 heads. 3 days later the bearings went. With grand hopes of replacing the cam and lifters with something radical I left the original laying around, and I mean laying around! When money didn't allow for a new cam and lifters I DUG the lifters out of the dirt, I'd been walking over them for months, and wire wheeled, disassembled and cleaned them, and wire wheeled the rust off the cam. The engine lasted a year (about 8 sets of rear tires) before it spun a rod. On disassembly it also had several broken valve springs but the cam was decent. Failure was likely due to 6000RPM (cheap tach)daily.
Fast forward 20 years.
Rebuilt an actual 428 and lost a bearing. Kept all lifters in order and redid bottom end. A week or two afterward the cam went flat.
Moral of the story: make sure you polish the lifters in dirt for a week
Fast forward 20 years.
Rebuilt an actual 428 and lost a bearing. Kept all lifters in order and redid bottom end. A week or two afterward the cam went flat.
Moral of the story: make sure you polish the lifters in dirt for a week
#24
First corollary of re-using a flat tappet cam: The chances of the cam living without going flat are inversely proportional to the dollar amount you have invested in the bottom end of the engine, multiplied by the inverse of how much you intend to use the boat / car.
#27
I'm not sure if the two banks rotate in opposite directions, but I have read that the lobes are ground at an angle to not only keep the lifters spinning but also keep the cam from walking out the front of the block. That is one reason why you have to have a cam retainer or button for a roller cam, but you don't need one for a flat tappet.
#28
To the OP - if you are thinking about using your flat tappet cam over again, first take a look at the bottom of each lifter. If any of them are showing a pattern that indicates the lifter has stopped spinning, then that means the lobe is already worn to the point that it will soon be going flat. You will see a little rectangular mark where the lifter is contacting the lobe in one spot in that case. The ones that are spinning will have a circular pattern.
#29
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I would agree. In my experience with them it has never made a difference. We spun them high rpm for yr after yr with no problems. I have fixed a few solid flat tappet cams and the lobes are tapered to the front so it pulls the cam back. We mixed them up all the time. Hell we even tried putting solid lifters on the exhaust in Stock classes to gain an edge never changed a thing tho. Us poor boys tried all kinds of crap but we learned a lot too.
#30
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I'm not sure if the two banks rotate in opposite directions, but I have read that the lobes are ground at an angle to not only keep the lifters spinning but also keep the cam from walking out the front of the block. That is one reason why you have to have a cam retainer or button for a roller cam, but you don't need one for a flat tappet.