Can someone explain to me what makes a block acceptable for hydra rollers. I have a 68 327 that I am in the stages of planning. Currently running fuelie heads, thinking of going to afr 180. I cant tell you anything more about the motor, ie cam, I do know that when I rebuilt the motor in 1983 I put new solid lifters in with a performance cam. The car has been in dry storage for about 11 yrs and is getting ready to be brought back to life.

You can run a hydraulic roller in there. All the aftermarket cam companies make cams, lifters, springs, etc. to do it. The factory hydraulic roller blocks were set up stock with a hydraulic roller cam, and have the extra machining and bosses for the factory lifters, hold down bars, etc. You won't run a factory roller setup in a non-roller block, but you can definitely run an aftermarket roller setup in a non-roller block.

Jody

Any Chevy V-8 block can be used with hydraulic lifters. You just have to get the correct lifters for the year block you have. The blocks that were factory equiped with hydraulic lifters can use the less expensive, factory type lifters. The earlier blocks that did not come with factory hydraulic lifters have to use the expensive "conversion" lifters.

The blocks are basically separated into pre-86 and post 86 construction. Most post 86 chevrolet small blocks are setup for roller cams. The front of a post 86 block is machined for a retainer plate that holds the roller cam into the block, the lifter bores are taller with a machined top face so that the figure 8 lifter retainers can be placed on top. They also have 3 bolt holes in the top of the lifter oil gallery tube to hold the spider assembly that in turn holds the lifter retainers down.

You can get retrofit cams and lifters that will fit in a pre 86 block. The retro fit cams require you to use a cam button to keep the cam from walking forward and back in the block instead of the cam retainer plate, and the retro lifters are linked pairs that prevent the lifter from rotating in the bores and destroying the roller on the bottom of the lifter and the cam lobe. Retro fit lifters are brutally expensive ($300+ for a set) where the stock GM roller lifters are about $90 a set.

You can use a production GM roller cam in a pre 86 block if you just cut the ears off the retainer plate and use it as a spacer behind the cam gear and then use a cam button. I'm using a GM Hot LT1 roller in my pre 86 block and it works fine. Just make sure that if you have a mechanical fuel pump you buy a cam with the fuel pump lobe, as not all of them have it.

just to clarify- not ALL post 86 blocks with one piece rear seals are set up for a roller cam- i have an 87 1/2 tone 4X4 truck block that has a one piece rear seal, and the old style lifter valley with no provisions for a roller cam- and nothing to machine to make it use factory parts. it also is not set up for the front thrust plate. i kind of thought that block would be a good base for a solid cammed 302 using an L99 crank.
i believe the trucks didn't get a roller cam until the mighty Vortec came out in 96, but perhaps some of the blocks were set up for the roller stuff with flat tappet cams installed.