So i tore my 1977 f250 400 apart the other day to put a mild cam in it and when i took the old cam out i noticed the cam bearings looked horrid. They were cracked and even missing small chunks. What could have caused this? is there anyway to replace them without dropping the crank? could the crank be damaged also? i noticed small scoring in one of the cylinders also. Maybe time for a shortblock? thanks alot!

 

Sounds like a bottom end rebuild or a whole new shortblock to me! Has it over heated or lost oil pressure? Both can trash bearings.

If you do need a rebuild you could probably get away with just honing and oversized rings for the cylinder walls. As far as the crank, pulling it will give you the best understanding of the damage.

 

Thanks for the info. I really don't know much about the motors past as I havnt owned the truck for very long.

 

The best thing you can do is buy a Chilton's manual and a book on how to build the 351c/m/400. It will show you the proper way to do pretty much everything you need to do.

 

You have a 37 year old vehicle with X amount of miles. Do you know if she's ever been touched...as in "freshened up?"

As 61steven said - yank, and rebuild time. Besides, you wouldn't put a new cam in a motor with 37 year old cam berrins, would you?

 

the guy before me said the motor was rebuilt but im begining to dout that