KagA152

iTrader: (5)

so whats the advantage to a cutaway lifter versus a solid? obviously weight, anything else? im trying to find a set for my build using a 638 block, so my choices are somewhat limited.

also, for a small base circle cam, do you have to use different lifters, or are longer pushrods all thats needed? does the .300" difference in the bore make any difference when using a small base circle cam?

sofakingdom

iTrader: (1)

That's the only real difference.

I can't feature having trouble finding lifters for a big block. If there's ANY ONE motor that has EVERY variety of lifter known to man, out there in the world in wide circulation, in every imaginable configuration (and probably a few you haven't imagined yet besides), that's it. Even more so than a small block.

With a small base circle cam, the lifter can descned so far in its bore at zero lift, that the oil passage cutaway around it, can actually pass below the casting, which will create a HUGE pressurized oil system leak, and eliminate your oil pressure (especially if ALL 16 do it); or the top of it can severely restrict the flow of oil to the other lifters forward of that one. The small base circle modification consists of moving the cutaway band upwards on the lifter so that it stays aligned with the passage in the block.

Yes you will almost certainly need longer push rods than you would otherwise. But since you'll be measuring for the correct push rod length anyway, and not just assuming something about what length to use, it won't matter, because you'll be fully assembling the entire motor, checking for the optimum length, and then ordering the correct push rods. So it hardly matters what length might have been appropriate for some other build-up.

I'm not sure what you're asking about the larger bore. I don't think the cam can see the bore, and get itself all worried about it. What are you talking about?

KagA152

iTrader: (5)

its for a small block, casting number 638 which is the 87-95 1 piece roller motor. i worded the difference in bore wrong, i should have put in bore height