Hi everyone. Im just starting to look at options for building a new motor for my IROC and I'm in need of some info here. I just picked up a bare 4 bolt 350 block the other day to start my build up on (its a 1974 4 bolt 010 block out of a truck or something, it originally had 160hp ). Anyway, I originally planned on building a 355 out of it but looking at prices, I figured for the same cash I can build at least a 383. I found really nice deal on an Eagle ESP 4340 Non-twist forged crank. It is listed with a 3.875" stroke for building a 396 SBC with a 6" rod. My first question is what bore would I need with this crank to make a 396. Is a 4.060 the right size? What do you think I could take this block out to safely? I've heard that .080 is about as big as you want to go with a factory block and thats with extensive testing to make sure the walls aren't too thin. Second question, how much clearancing is needed to make this crank fit and are there safety issues with clearancing out this far?

So thats what I need to know. Im shooting for 500hp at the crank N/A with a 200hp shot of spray on top of that. Eagle rates the crank at 1500hp so that shouldnt be a problem. The rest of the combo will consist of around 11:1 CP pistons, a Comp cam (havent finalized a grind yet) AFR 195's (at least, I might go bigger) with a Stealth Ram to top it all off. Im going to back it all up with a TH400 and probably a 12 bolt or I my just build up my existing 9 bolt.

Thanks for the help.

 

Bore it AS LITTLE AS POSSIBLE, especially if you intend to spray it. 1 or 2 extra inches aren't worth the hassles that paper-thin cyl walls give you.

For all practical purposes, that means, bore it out .030"; and however many inches it is, that's how many inches it is. Odds are though, it's already .030" over; in which case, bore it as little as you possibly can that will clean up the wear, and that you can also buy pistons in your desired configuration for (not a trivial matter unless you're planning on $custom pistons$ anyway).

 

Its a virgin block, never been bored or decked. Already mic'd it

 

4.000 + 3.875 crank = 390
4.010 + 3.875 crank = 392
4.020 + 3.875 crank = 394
4.030 + 3.875 crank = 396
4.040 + 3.875 crank = 398
4.060 + 3.875 crank = 401

IMO, i'd only go .010 unless your cylinder walls look bad and get a 392 made. Anything over .030 is not going to last as long and the cylinder walls won't be as strong. The extra 4 ci you get from going .030 won't make any difference at all as far as vacuum or power. I contemplated this myself before I decided with a 383. Another thing to note with a 396 is you may have to use a smaller circle cam to make up for the extra clearance needed to go 396. There is also more machine work involved in a 396 opposed to a 383, the oil pan rails usually need clearing.

 

Thanks for the info Pasky. Looks like I'm going 396. The cylinders have some surface rust and whatnot so we are going to take it out to .030. The clearancing shouldn't be a problem. The shop I'm having it built at is pretty good and my buddy that is specing everything out went to S.A.M. down in Texas. He built a few race motors down there so we shouldbe good on that end. I also own a shop myself but we dont normally build motors. I do have the equipment for assembly though. Should be a wicked motor.

What do you guys think about those heads? Should I stick with the 195's or go bigger like 210's or 220's? Shooting for 500hp N/A. I'll get cam specs here in the next day or so.

 

210's, you won't see much gain over the 220's as there is a loss in velocity. Now if you want to go all out power....Buy some trick flow 18* SBC race heads, those things flow ****en crazy and get a Hogans intake made and you'll be puttinf down 500+ rw N/A with the right cam.

 

I dont know if I want to go that hog wild with the 18* heads. Depending on the price a Hogans manifold may be cool but I doubt it will be as cheap as a stealth ram. Any idea what they go for?

*EDIT* Holy cow. A Hogan's single TB EFI manifold is $2500!!! No thanks.

 

You get what you pay for, like I said, thats what I would do if I was going all out . You can't go wrong with AFR's. Get the 210's.

 

Isn't a 396 a big block? Ok, I know a 396 is a big block, so how does it work that you could put a 396 crank in a 350, bore it over and make it a 396? That is what you're saying right?

 

Jbqualls- what 88blkiroc is building is a small block that will end up being 396 cu in. It is a coincidence that GM built a 396 big block. On the other hand, in 1971 you could buy full size cars like the Caprice that had "400" fender badges (trucks too) and they could either have the 400 cu in small block OR a 402 cu in big block. Confusing isn't it?

 

Interesting...

 

Im building a small block 396 like Eric said. Its a 4 bolt 350 block with a Eagle 3.875" stroke crank (stock is 3.480" I believe) with a .030 overbore on the cylinders. Just like building a 383 but a little bigger.

 

Do you have your rods and pistons figured out yet?
What's the rest of the combo going to be like?

 

I'm going to be using a 6" rod, probably Eagle but I haven't decided for sure yet. For pistons I'm going with JE, but I dont know the specs on them yet. Going for around 10.5:1 compression. Still no cam picked out but I'm working on it.