Groove In BBC Lifter Bore

[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.

[Jeff Stout]

I thought once on a BBC I had the builder ground a small flat on side of lifter from groove down to base of lifter, thus making a cavity for oil to run down lifter to cam

[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.

[Dwight Southerland]

Originally Posted by carl hinkson

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.

Carl -
Not wanting to start a p***ing match here, but that is not exactly true. First, it is not a flat surface, and it does effect valve timing events. Secondly, I did not refer to valve timing events, but rather to valve train problems that are caused by harmonics. Thirdly, I agree with you 100% about lifter bore clearances and oil bleed off. Grooves are not necessary if everything else is kosher.

[carl hinkson]

Originally Posted by Dwight Southerland

Carl -
Not wanting to start a p***ing match here, but that is not exactly true. First, it is not a flat surface, and it does effect valve timing events. Secondly, I did not refer to valve timing events, but rather to valve train problems that are caused by harmonics. Thirdly, I agree with you 100% about lifter bore clearances and oil bleed off. Grooves are not necessary if everything else is kosher.

Can you read what I said so to SPEAK was it that hard for you to figure out what I was talking about. LMAO

Again having a lifter bores off any amount will not affect seat timing events on a flat tappet build it can't because the cam is riding on the convex surface of the lifter.

Hope I explained it so you can understand LOL

How come they call them flat tappets ??????????????????????????? LOL

[Dwight Southerland]

Carl, you have to allow for the fact that the angle of the lifter bore is also off in the old blocks. That does effect the valve event timing regardless of the lifter type.

[carl hinkson]

Originally Posted by Dwight Southerland

Carl, you have to allow for the fact that the angle of the lifter bore is also off in the old blocks. That does effect the valve event timing regardless of the lifter type.

It would have to be off 5 degrees to have any effect and I have not seen any that far off.

Do machine lifter bores ???