I've got a 350 block with the one- piece rear main seal and no fuel pump rod hole that I was told came out of a 1994 pickup truck. It is casting #14093638, which Mortec says is a 1986-87 part.
Anyway, it has the bosses in the valley for the roller rocker "spyder" that are not drilled and tapped. The walls of the valley also appear to be releived for tie- bar clearance. And the front of the block has "ears" around the cam area where it could also be drilled and tapped for the roller cam retainer.

So I'm wondering if this block will truly support a hydraulic roller cam if I drill and tap these areas and get the parts for the new mountings? Are there any other features that the block would have to have for it to work? Or can I even run a solid lifter roller cam? Is there any GM solid roller cam setup available utilizing this setup?

 

You listed the important features.

I've heard talk of it, but never of anyone actually doing it. Are the lifter valley numbs machined flat, or just there?

 

If the 3 bosses are already milled flat on top, and the area between each pair of lifters is already milled, then just drill and tap.
GM has never installed a solid roller cam set-up. And it doesn't matter about those 3 bosses if you are going solid roller. You will just need to make sure the link bars on your lifters clear the block. The cl;earance issues here will be when the cam is turned to where the valves are closed. If you do find any issues, you can either disassemble everything and grind on the block, or send those lifters back and get a different style.

 

The three bosses for the spyder mounting are as- cast, not machined. But they are nice and flat and straight on top. Unless there is a height issue where they would need to be machined down, they look like a nice surface to mark using a spyder, centerpunch, then drill and tap out. Maybe run a file over the surface first.........

The area around the front of the cam is machined flat. I've heard that there are two different sizes of cam retainer plates, meaning two different bolt hole spacings, over the years? There looks to be plenty of room on the "ears" to drill and tap for either size of cam retainer plate.

Thanks!

 

Oh, and that brings up the question, is it worthwhile to go to the trouble to do this stuff to the block to use a hydraulic roller cam? I will probably only build a mild engine with cam lift that stock Vortec heads could handle, probably no more than .475 lift. I might modify the valve guide bosses for a little more lift, but I want to keep it slightly economical for the street. The last engine I built for everyday driving only had .454 lift and it ran well and sounded pretty nice so I was pretty happy with it. I'm definately not looking for the most horsepower at any cost.
Are there enough benefits to make a hydraulic roller cam worth it for a mild engine like that?

 

I would do it (do the factory HR setup), it isn't that hard. I've done it on fords and it's quite simple, and it's pretty much the same setup. Junkyard or eBay all the hardware and stuff (spider, spider bolts, dogbones, maybe lifters, factor roller retainer plate, and retainer bolts). Then just find a factory roller grind you like and there you have it.

As for hyd. roller versus a flat tappet kit, the cam itself can be made more aggressive, with faster valve opening and closing rates, compared to a flat tappet, so cam to cam (roller versus flat tappet), the "area under the curve" will always be greater on a roller compared to a similar spec flat tappet. But, in the end, it all comes down to price invested justifying the outcome, flat tappet will always be cheaper than roller, and power can be made with either design.