Went

Hi all. Jim Barth is putting a 383 stroker together for my 89 vette. The 4-bolt main block we thought was good had two cylinders that didn't clean up till 0.60" over. All the others cleaned up at 0.030". So we've been on the hunt for a good condition 4-bolt main block. That's been hard to find right now. There's new...about $980. Then there are 2-bolt main blocks. Jim thinks we'll hit approx 475 HP, 500 torque. Opinions on a 2-bolt main block? Anybody running a 2-bolt block 383? Or should I just bite the nearly $1k bullet and buy a new block? I'm going to sleep on this a few days. Just looking for some thoughts.

I have no drag strip aspirations...but you know how that goes. Daily driver...maybe some autocross driving after I retire.

Went

ddahlgren

Do you already own the rotating assembly? Personally I would look for a used block 4 bolts is best but if a 2 bolt block fit the same relative quality of everything else I would not sweat it. I also would not have been concerned it the pits or whatever was below the ring travel and would have left the pit there. I have run 550 hp engines on outlaw short tracks that ran at 7800 or so RPM for a season and never broke a cap. Ran 1/3 to 5/8 mile high banked asphalt ovals and was quite competitive on the 1/3 mile but middle of the pack at 5/8 mile.

cv67

Similar situation years ago, burned up the plastic and bought a new block, glad I did.
Noones screwed it over, no worn lifter bores etc. Unpacked it, did some final machining and know I had a perfect foundation.
Spend it youll be glad you did. If youre leaning on it youll always have in the back of your mind, "is this 2 bolt gonna pop"? or not-
A studded 2bolt can handle some abuse but if youre going to drive it hard regularly/track it Id take the hit now.

at the end of the day Jims your builder Id follow his lead.

Jim84

I don't know anyone who used them, but you can buy main caps that have the two bolt holes straight down, and the two outside bolts o at a slight angle which is supposed to be super strong. You will have to have a machine shop drill these holes.
Summit had 4 bolt blocks for $700. (last year, haven't checked lately)

Joe K

Can't sleeve the bigger holes? Do they do that anymore? Just a thought. Sounds like a nice project!

Joe K

WhiteC1

Not sure where you're located (I'm in Michigan), but I have a 4-bolt block I took out of my 95 Vette. It had one spun rod bearing, but otherwise it's OK. If you're interested, I can give you more details. Let me know.

Regards,
John

bfit

If the block cores were centred bore the block to +0.090

84 4+3

Look for an l31 block at a yard. 4 bolt main block for relatively cheap. Should be around 500 for a running one and less for a stripped one. Just my input.

DVNCI

Ditto - Jim's forgotten more about building motors than I'll ever know!

Went

Jim's already purchased the stroker crank, 6" forged rods, pistons, rings, cam, heads etc.

383vett

That's patchwork engineering for a new motor. Op, whatever Jim recommends, you will be fine with.

vader86

I would have to have one for the piece of mind, if you have to buy new then do it. But if Jim says he thinks its alright to stick with 2 and not do extra splayed then I trust him.

RichS

I've been running a 2-bolt block that had the 4-bolt splyed caps put on since 03 with no issues. I've put over 1000 1/4 runs, autox, and road raced it over the years.

Tom400CFI

This. Jim lives w/in minutes of two 'you pull it yards' that are littered with L31 Vortec blocks. 1pc RMS, roller cam, 4 bolt block. You can pick 'em up all day long for less than $120 ($99 plus $20 core). I'd even go help Jim yank one b/c he's such a great guy to hang with.

The other option is the local classifieds; KSL There are almost always 350, 4 bolt blocks on there for pretty cheap. I just bought a good, SBC 400 short block for $150 through KSL.

A quick look revealed three options:
FIRST Vortec 350

SECOND, two piece 350

THIRD

That first option...I bet you could bore that .010 over and it would be fine. Those Vortec engines (when oil changed) last forever. I just sold a truck with that engine with 296,000 miles and it still ran like new, didn't burn oil. A GREAT place to look for 4 bolt blocks.


.

ddahlgren

Call me old fashioned but with a new build I always started with a prepped block and ordered parts to suit. The block might clean at 0.010 and if so little sense in throwing away cylinder wall. Or it might clean at 0.040 or get crazy lucky and get a buy on a ow tie block and cleans at 4.135. It also does not box you into 1 or 2 piece rear seal either.

Courtney H.

People still sleeve cylinders. They work, but if you are skeptical, then don't fool with it. A 2-bolt block, properly converted to a splayed 4-bolt, is claimed to be superior to OEM 4-bolt. A seasoned block is better than a new one. I wouldn't buy new, unless it was a high-performance, or heavy-duty block. And even in cast iron, them babies are expensive.

cv67

Seasoned vs new is debatable. Ill take new any day...to me seasoned says "old and used up" none of us are endurance racing.
Whatever fits the budget I suppose...got tired of sinking $ into older blocks only to find some hack machined it improperly or skipped over lifterbores and that new engine makes noise.

Need A Vette

If you're worried, I'd take my 2 bolt block to the machine shop, order the splayed main caps, and have it drilled, and tapped for the 4 bolt splayed caps, and yes, they are to be stronger than the straight 4 bolt caps. Not sure what the cost would be, but I would absolutely look into it.

D.

sstonebreaker

Here's a thought: Get a two bolt block and machine it for splayed four bolt caps. The production four bolt blocks use straight alignment, with all four bolts parallel. The GMPP race blocks use 20 deg splayed bolts, as these go into the strongest part of the block. Buy a good two bolt block and have it machined for splayed four bolt main caps.

STH

I'v been running a two-bolt main 383 since 1997, I did upgrade from bolts to studs on the main caps, but as said if your worried I'd have a two bolt block machined for splayed caps, over a factory four bolt block.