dj haf

i was looking online and i found a 350 block from gm that i was curious to know would work if i wanted to build a 383 stroker out of it. is this block any good to make a 383 out of? or should i check out another block? i have a 1990 iroc-z with a 350 that's already been rebuilt, but i think the rings are toasted now because it looks like i have a nice case of blowby that keeps getting worse and worse.... so im just going to build a 383, put my heads, my cam and the hsr intake i have on it and hope for the best. thanks for the help guys

http://www.gmpartsdirect.com/perform...CATID=628.html

RB83L69

It's basically the same as the block you already have, except new.

That's a pretty expensive way to come up with a block; considering how many late 80s - early 90s trucks (again, same block) there are in junkyards these days.

dj haf

yeah, but i dont know what kind of condition those blocks are. it's a little piece of mind to know i have a new block that won't have any problems because it has never been used (and abused).

Val

Once a machine shop is done with it and magnafluxs it, all doubt should be removed from a junkyard block. And you need to do that with the new block anyway so you could save some $$.

Some people hold that "seasoned" blocks hold up better, as the years of heating up and cooling have tempered the iron. I have my doubts about that, but several racing firms do cryo their blocks for a similar but far better effect.

RB83L69

To me, it would be alot more "peace of mind" to have a higher balance in your bank account, than a "new" block. Blocks don't suffer too much from "abuse". Their "condition" doesn't matter, because you'll be hot-tanking it, boring it, checking it this way and that, etc. etc. etc., all of which pretty much erases the "condition" you found it in.

In the grand scheme of things, that's ALOT of bucks, in exchange for VERY LITTLE bang. Considering you could either get a wore-out truck motor for about $50 and bore it .030" to make your 383, or buy a brand-new block for what, 10 times that much or so, and then bore it out .030" to make an otherwise identical 383, it seems like a complete no-brainer to me.

But, it's your money; so if you want to use it that way, you're perfectly entitled to do so. And as I said, that would be the correct block casting for your application.

dj haf

hmm... i think you've helped change my mind, lol

should i get a block with a 2 or 4 bolt main? and which blocks have which? truck blocks have the 4 bolt right? if you've got any helpful information into which block i should choose from (since there are a lot of different kinds of 350's), let me know. thanks for your help guys

RB83L69

638 casting, is all you need to make sure of.

Trucks motors don't have roller cams, as they come; and you'd want that. The block will most likely have the retainer holes in the front, ready to use; and the tops of the lifter bosses will be machined for that goofy factory lifter retainer setup. The bolt holes to bolt it in may or may not be drilled & tapped, but the bosses will be cast in for them. Your machine shop can easily drill them out for you.

Truck blocks are mostly 4-bolt main. It really doesn't make alot of difference one way or the other though. Factory 4-bolt setups aren't designed as reinforcement for racing-type stresses anyway, so they don't do much one way or the other to improve the block for our typical application. But if you've got TPI on your motor, unless you've also got 200 HP of nitrous, it'll never see the kind of stress to where the # of bolts makes any difference. TPI takes care of that for you.

dj haf

i have dart ie heads, hsr, and a cam with 224/230 dur. and .535/.544 lift (with 1.6 rockers). eventually im going to supercharge her, so i want to put in a strong bottom end. might end up going with a forged bottom end setup so that i have a reliable setup with all that power.

is there any year in particular that i should look for? or do i just call around junk yards and ask them if they have any 350 blocks with a 638 casting? i dont wanna get the wrong thing... so im just asking to make sure. thanks

RB83L69

Tell them you need a block from (not FOR, but rather FROM) a 87-up 350, for your 91 pickup. Then when you go to buy it, make sure it's a 638 casting.

dj haf

how much power do you think i can hold with this bottom end?
ESP-B13054E030

like i said, eventually i'm hitting her up with an ati procharger, so i want to make sure my bottom end will hold up to 550-600 hp to the crank. u think this is achieveable with that kit?

fireturd350

iTrader: (8)

Well at least it has forged rods and pistons. You could probably get away with a cast crank if you don't push it crazy hard. After all car mags. do cast build up putting out 500+ hp at the motor NA. Being cast steel instead of forged that will save you a little weight. Willie did manage to break his supposely "forged" crank in half with his crazy high teen/low 20s lbs of boost off his ATI... though that's not his fault since it was really just a cast crank.

I'd definitely find out the actual compression ratio with those pistons before making a choice. It would be a bummer to get them and then find out you only get around a 9.x:1, then have to rebalance the assembly for a new set of pistons. Full floating pins are definitely nice if your a DIYer that way you don't even have to pay a shop to press the pistons and rods together, instead you use the nifty little spiral-locks.

I know when I put together my assembly I matched parts up myself over buying a kit. Which now includes a 4340 forged ESP Eagle Crank, 4340 China-Imported I beams (floating), and a forged set of TRW pistons after I had it balanced it ran me ~$1500 or so total.

Make sure you have the shop clearance the block for a 400 stroke, else you'll be using a die grinder on the rails yourself taking out the extra material to let the crank turn over.

dj haf

can i ask why they need to clearance the stroke if it's got a 3.75 stroke? im just going to get the block and the parts and give them to my friend who owns a machine shop to build it for me. he told me he'd get the parts and do it all himself - but i think he'd charge a little bit more for that and im trying to save up a little, ya know? would it be cheaper if i bought the rods, crank, pistons, rings, bearings, etc seperately, or in a kit? any advice you guys can give would help a lot! =D

fireturd350

iTrader: (8)

The clearancing is needed because GM never intended the 350 blocks to be used with a 400 crankshaft. So when you build a 383 you're going from a block that use to have a 3.480'' to a 3.750" stroke. That means by having that add'ed throw there is a chance of the big end of the rods or bolts to hit off the bottom rails of the block. So, they have to be notched in that area.

Well the nice thing about buying a whole kit is they usually come balanced already so that cuts down on the time and cost needed to weight match all the rods, pistons, and balance the crank out to those weights. Main thing to look for is if it's internal (350 balancer) or external (400 balancer) out of the box.

If you're ordering from Summit Racing or Jegs take into account both do pricematching. The catch is the place with the better price needs to have a storefront, meaning a walk in location. This is in place to cut out the places that just do pure drop shipping, since their overhead isn't as high. Basically collect the price information, store name, store location, and phone number or url so Summit or Jegs can check the price. I've easily saved hundreds of dollars this way on an order.

I bought most of my items seperate, the gaskets you pretty much need to get a complete engine gasket kit since some of those you can't find seperate. Also if you buy a piston or rod kit in a set of 8 they'll usually come weight matched out of the box to +/- 1 or 2 grams.

It pretty much comes down to personal prefrence. If you find a kit from a respectable company that will work and for a good price then that might be a better ticket.