Yesterday, while stripping my engine to do a cheapo rebuild, I pulled my TPI intake only to discover I don't have a factory roller block. A little background... I have a 91 Z28 5.7L. Over the past couple of years, I have acquired enough spare parts that I'm not intending on keeping forever, (the parts fit a roller block, 1 piece RMS, std bore). So I figured I would just go ahead and put them in my Z28 and sell the short block when I'm ready to upgrade. I planned on honing the block, cam bearings, deck it if needed, recon the rods, and freeze plugs. I have a CC306 cam to put in it, some forged std pistons, moly rings, Canfield heads, and a HSR.
Well, now since I can't use my factory roller lifters I have in this block (it is still a 1 piece RMS, but isn't cast in the lifter valley for the spider plate), I think I can buy some aftermarket style lifters that will fit since the lifter bosses aren't the 'tall' roller type in factory roller blocks. So I guess my question comes down to this. What do I need to do run a factory type (step nosed) cam (the CC306) in this non-roller block? Can I just run a roller cam button with a non roller block cast aluminum timing cover? My understanding is that the roller blocks won't accept a retrofit roller lifter set because the lifter bosses are cast taller than nonroller bosses (without machining), but I should be good with the retrofit roller lifters since my block is not cast with the tall lifter bosses... is my thinking correct?

 

You'd have to try it with a retro roller lifter and see if there's clearance.

 

Well, I just went out and measured the lifter bosses.... they are a good 3/8 - 1/2" shorter than the lifter bosses in a factory roller block. I guess this is why you can't run retrofit roller lifters in a factory roller block without machining.