92blue

iTrader: (1)

I am being a offered an 86 350 block, one piece rear main seal. Problem is, I wanted to go with a hydraulic roller cam. I know some blocks have provisions that I can tap and install the spider. I already have that on my 305 that I can use. Here's my question. I know the blocks that don't bring the spider have provisions for it from 87 on up. What about 86? Do I need any other type of machine work? If I do, how much would that run (ball park figure)?

Acidtalons

Unless it has pads cast in that will allow you to tap for the spider you are probably not gonna be able to run the GM roller valve train.

However aftermarket lifters are avaliable that will allow you to bypass this.

Not sure about the machining costs but I am sure they wouldn't be over $150 bucks. If the block is free and in good condition take it either way.

Bear in mind however, if you are paying for the block and want to run roller and its not setup for that then you may want to pass on it.

I recently picked up a good condition ZZ4 block, crank, rods flexplate windage tray and pistons with 120k miles on it for $250. Planning to rebuild the whole thing but the roller block alone was worth the $250.

A brand new roller block from GM is $700, don't let the cost of the block, bore, hot tank, and honing exceed that.

92blue

iTrader: (1)

In that picture right there, the three holes that stick out in the center of the block are what attaches the spider correct?

RB83L69

Yes.

Note what it is that they're cast on top of: it's the oil passage that feeds the main bearings, the rod bearings, and the cam bearings. Definitely not the sort of thing I'd be drilling into if the bosses aren't already there to allow you to drill a blind hole without hitting pressurized oil. The most critical pressurized oil passage in all of the motor at that.

92blue

iTrader: (1)

Aside from tapping the spider, does any machine work need to be done around the lifters themselves? I've spoken to three of four machine shops already. One guy seemed to understand what I was explaining to him, but wasn't very helpful. Machine shops here in Miami for the most part are interested in rebuilding and installing the whole engine themselves. Most of them seem to get annoyed when someone wants just a specific service. The other two or three shops seemed hesitant and unsure of what they were telling me.

I don't see a reason why I can't drill and tap the spider bosses myself. I just want to be sure thats the only thing that needs to be done to the block. I am not too fond of last minute surprises.

RB83L69

Drilling and tapping the spider bosses, if there aren't spider bosses which there aren't any of if it's a pre-87 block, is exactly what you don't want to do. You'll be drilling and tapping directly into the most critical oil passage in the whole motor; the one place you don't under any circumstances want a leak.

But in any case, in order to make the factory's goofy retainer things work, you have to machine down the top of the lifter bores, so the retainer pieces have somewhere to sit.

Basically, if you have an older block, you need to use the roller system for older blocks, and forget about attempting to graunch the factory's Frankenstein into it. It'll cost you less money and trouble in the long run.