I have a 1962 413 300 H motor, It had sat for well over 20 years and upon disassembly showed it had a significant amount of wear. I had it decked, bored and the heads professionaly gone through with hardened seats and bigger valves . I put in new bigger pistons, new rings etc. I also converted from the factory solid lifters to hydraulic lifters along with a mopar performance cam. The car took a while to start and upon driving it, it smoked from one exhaust pipe and did not run properly. We found that it rounded one of the cam lobes. We replaced the cam with a comp cams with a similar profile to what the mopar performance cam was, just a little less aggressive. In the mean time the car also overheated in between some of the issues. After the overheating and a little more driving the car started smoking terribly from both tail pipes.
I just pulled the motor again and found another rounded cam lobe( not on the same one as before) on the exhaust port. I have not gotten the pistons out yet, but am thinking that the oil rings will be shot. from the over heating It also appears to have slight vertical makings on the freshly bored walls.

Any thoughts on why it keeps rounding cams off? I went through the break in procedure on the second cam to a t.

 

Hi,
you will need to get an oil additive with zinc in it.
today’s oil does not have it any more.
And zinc is a must to run in a flat tappet cam
Thanks

 

It could be that the valve springs are too stiff for the initial cam break-in. Check the paperwork that came with the cam and see if they advise using a lighter spring with initial breakin. I have heard and read that zinc is a good thing to add, but I have never added it and never had any problems. I would reccomend you use it, just saying that its not the reason for your troubles. If I were you I would take the engine out and tear it back apart i would have the machine shop check the lifter bores to make sure that they are all good. If they are it could be possible that its not getting enough oil in or to the lifters. check all the holes and clean them out. Recheck all the clearances and since its apart check the main and con rod bearings now that you ran it just to make sure that everything is good. I would also check the piston to cylinder clearance and make sure that there is enough clearance for the pistons you used. This could be a reason for overheating and the unusual wear pattern on the cylinder. I had a 340 that came back from the machine shop ready to assemble and spun two rod bearings because there wasn't enough clearance in the bore. Don't trust all machine shops they make mistakes sometimes. One good thing to also check if you have not allready is that since the block and maybe the cylinder heads were decked, the pushrods may not be the correct length. Dissregard if you used the original adjustable valvetrain.

 

like they said before, either the springs are too stiff or it has to do with zinc
here, read this: https://moparforums.com/forums/f62/o...-engines-2333/

if you keep on rounding the cam, make sure you dont have bits of metal in your motor. they could eat up the berings.

 

Welcome to the forum,lots of good advice here!
Did you prelube the motor before starting? What was the oil pressure?

Make sure the lifters spin freely in their bores, if they don't that will wipe a lobe.

Good luck,

john