Groove In BBC Lifter Bore

[carl hinkson]

Originally Posted by Dwight Southerland

If you are not using a new CNC'd block (GMPP. Dart, etc.), there are multiple advantages of bushing the lifter bores. 1) Blocks from the 1960s are notoriously out of register. Having the lifter bores correctly aligned will eliminate potential vale train problems. 2) The bushings allow for tighter clearances, thus more accurate movement. 3) Less wear 4) You can restrict the amount of oil to the top end easily, thus allowing more oiling to the camshaft bearings.

If you are concerned about oiling the camshaft-lifter surface, you could have a vertical groove from the galley hole to the bottom of the bore.

On flat tappet cams the lifter bores could be off .010 plus and not effect seat timing events as the cam is riding on a flat surface so to speak. If the lifter bore was off say .012 and you moved it in the opposite direction .024 which would be .012 off center on the opposite direction its not going the seat timing events at all.

That being said on roller lifters being off .012 plus it does change seat timing events which causes an intake and exhaust imbalance plus compression from cylinder to cylinder would not be the same.