383 cam lobe issues

[Gator]

ok here i go im new here so hello to everyone . im currently building the second engine this year for my challenger . Its a 383 bored .040 i installed kb 400 pistons with 452 heads . now my problem is i wiped out the first cam and now rebuilding again as metal distroyed the crank and bearings . I have read all about the low zinc in the new oils as i have finaly acceped that i used the new oil and was told it had enough zinc . so its really puzzling as to why the cam whiped out . I did the proper break in on cam 2000 - 2500 for 30 minutes then didnt notice the metal in the oil till it was too late it ate the bearings so bad the engine locked down , then i seen the metal on the dipstick . So now im taking all the precautions i can comp cams 280 h kit as comp says they wont warranty any part if i dont use all there parts . I have never ran into this before and have built several engines in my life time all fairly stock so this is my first attempt at a performance engine . any help on this would be greatly apreciated as i cant afford to rebuild this engine again .

 

[nqkjw]

I have read all about the low zinc in the new oils as i have finaly acceped that i used the new oil and was told it had enough zinc ..

New oils DON'T have enough zinc unless it's a specialty oil for older engines.

I use diesel oil in mine.

For a new cam use proper breakin compound and use a ZDDP package in the first sumpfull of oil.

 

[burntorange70]

Welcome to FEBO. Adding Zinc will help. Also I heve hered if you are running double valve springs you should remove the inner one during cam brake in to take some pressure off the cam lobes then reinstall it after brake in.

 

[Gator]

Thanks I just think all this stuff about oils is confusing . I read on the net that rotella doesnt have the zinc content it needs since they have added cat converters to big trucks i also read that some zinc additives have compatibility issues couldnt find out what brands this is happening with .. so its all getting confusing. im going to use comp cams break in oil then as the comp cams instructions say change oil then ill use rotella with the additive and hope all goes well. ive been tyrying to get my 73 challenger together for 2 years now with setback after setback feel like im working on a boat its all been about bustin out another thousand

 

[ramenth]

Welcome to FEBO. Adding Zinc will help. Also I heve hered if you are running double valve springs you should remove the inner one during cam brake in to take some pressure off the cam lobes then reinstall it after brake in.

That was actually my thought, too, was spring pressures. What rockers are you running? Adjustables and too much pre-load can cause this. Did you prime the engine? Just asking, don't take offense as a lot of us see this as a no-brainer.

Welcome aboard, by the way.

 

[burntorange70]

I here you. There is two threads, very long threads over on FABO about oil and zinc. Like Ramenth said it is also about spring pressure. To much during brake in can wipe out a cam lobe easy.

 

[Gator]

I wish everyone a safe merry Christmas. im running stock rockers and installed the stock springs today . I also noticed that the pushrods were different in 2 of the 383 engines i have and noticed that when installed they load the lifters at different preloads so i installed the ones that look to load them at about .020 or so as the other ones seemed to preload at about a 1/4 inch didnt have anything to gauge them exact but im thinking if they are preloaded too much that would put more force on the lobes cant seem to find any information as to what the stock length of the push rods are from the factory . wont fire this engine till im sure of everything . both the engines i have are 68 year model so i dont know why they had different pushrods , maybe been changed at one time . i know one set has a tapered end and the other set is the same on both ends the tapered end set is longer and adds more preload . I have also read that it takes time for the cam and lifters to break in so im unsure as to how long to run the stock springs before going to the comp cams recomended springs as i wont be able to drive this on the streets for a period of time .

 

[ramenth]

I wish everyone a safe merry Christmas. im running stock rockers and installed the stock springs today . I also noticed that the pushrods were different in 2 of the 383 engines i have and noticed that when installed they load the lifters at different preloads so i installed the ones that look to load them at about .020 or so as the other ones seemed to preload at about a 1/4 inch didnt have anything to gauge them exact but im thinking if they are preloaded too much that would put more force on the lobes cant seem to find any information as to what the stock length of the push rods are from the factory . wont fire this engine till im sure of everything . both the engines i have are 68 year model so i dont know why they had different pushrods , maybe been changed at one time . i know one set has a tapered end and the other set is the same on both ends the tapered end set is longer and adds more preload . I have also read that it takes time for the cam and lifters to break in so im unsure as to how long to run the stock springs before going to the comp cams recomended springs as i wont be able to drive this on the streets for a period of time .

Merry Christmas back atcha!

The difference in the pushrods could have been your problem. As for the different lengths, you've got one on me. I don't know. But it does sound like they been changed.

As for the break in period you'll hear five different guys give five different answers. We usually run it up to about 2500 rpm for the first fifteen minutes, back it off to around 1500 for the next ten or so, and run it back up to 2500 for another ten.