I have this 638 casting block I bought it for 50 bucks complete with heads and intake. But guy told me it had a head gasket failure. So I removed heads and intake but yet to do anything with the block. Because I honestly don't know what I need to do next.
I know it needs to be cleaned the valley is full of gunk and the coolant passages are rusted. I can also rotate the crank by hand very easily cylinder walls look fine to me. A friend told me to just drop new heads on it and swap it in. But I don't know if I actually can do that. Should I just clean the damn thing and run it? Or is it highly recommend that I completely take it apart and send the block to get machined? I don't really mind getting a over bore done since I plan on running nitrous. But if I don't have to I won't.
I plan for a Vortec 350 with a single plan and nitrous. HP limit is 300-400 until I get a better trans and axle.
Also I've read something about a 366SBC a .030 over and a .100 offset grind on the crank. Does doing this call for a rebalance or new parts?
Thanks in advance for any help. I honestly should have gotten this thing running already but I don't know what is the next step. Crank casting couldnt find much on it besides it being stock.


Some parts on the crank looked to be shaved off likr for clearance.

 

I don't see anything shaved looking about the crank. Looks bone stock to me.

I don't see blown head gaskets either, at least not in what you're showing.

Looks like a high-miles truck L05. Flat-tappet cam, dished pistons, the whole works. That was, what 200? 210? HP, in factory trim.

Just based on the mileage and overall look of lack of care and general deterioration, you should replace the bearings & oil pump at least. To clean up the lifter valley gunk means a tear-down, which means new rings. No sense in putting new rings on those old stock low-compression pistons. Of course it'll need a new cam & lifters.

Not hard to see where that ends up taking you.

I wouldn't mess with the offset grind and all that. Bore, yes; the other, no.

Depending on your goals and budget, might be just as cost-effective to turn it in as the core on a "rebuilt" one.

 

Goal is just a cheap block I'm not gonna make alot of power. I'd like to reuse the entire rotating assembly and just add can, lifters, heads, and intake but if cylinder walls need to be bored or honed then I'll update with cheap pistons.

To clean it I'd still need to tear it completely down. Right? And since I'm doing that I might as well update bearings, oil pump, pistons plus rings, and what else? My only issue is if it really really needs to be bored and honed.

Is more cost effective just to run my 305 with 305 Vortec heads or a set of 416s? I know this thing is running like a top. And 300HP is not unheard of off a 305.

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If I were gona put nitrous on it and abuse it anyways id just clean it up and run it as is.