340 lifter bores bushed or not ?? Solid Roller cam

That's the whole problem....few people say "Get the lifters bushed by a shop with a Rottler, Centroid, or equivalent machine...." They just say 'get the lifter bores bushed.' Many shops don't have CNC equipment.

It's also a mistake to assume that if a machine is CNC, it somehow is magically accurate. For one thing, the program must be right or the machining won't be right. You also have to properly load the machine and establish the proper reference point. Get those off .020" and all your holes will off .020". Use a worn or chipped cutter and it affects things. Finally, CNC machines have error just like any machine. I have both a CNC and manual mill and when it really matters....I use the manual.

I have a friend who worked for Dodge in the 1990's/2000's...he was a lead machinists and one of his jobs was visiting all the engine plants to make sure they were running machining ops properly on the SB Mopar engines including the race blocks. The degree of care they took in lifter bores was most likely beyond the capabilities of just about any normal shop. Here's one cut from an email he sent me

"We had Unbelievable carbide lined bushings to locate the lifter holes..A +- .0002 and held less on the seat 6 blade cutter head that was ground and the mastered to all be .0002 to gauge. with .0001-.0002 taper to hit high on the seat with what ever the miss, half degree or what ever but had to be right on the spot. Way over kill."

The point being....if the factory bores are 'off' it's most likely a result of the production speed, not tooling....and in any event, I think the factory bores are pretty good. And there are shops who also do a very good job of bushing them. It's just not a given that the factory bores are junk and any bushing job is awesome.