Gbody6liter

Hello all, I recently sold off my 6.0L iron block to get me a mid 80's 454 2bolt main block and TH400 trans. The engine was supposedly running when pulled and the trans is a core. I read up on Chevy High Performance converting the 2 bolt block over to a true 4 bolt by drilling/tapping the block and original 2 bolt main caps. The other thing I have come across is installing the Eagle or Milodon 4 bolt conversion caps, but they only cover 2,3,4 and not 1,5. Is it really that big of a deal? I am looking for 650-750hp on motor with 11.5-12:1 static comp. ratio and AFR 335 heads. This will be going into a 1986 Olds Cutlass G-body that will see some street use but mainly 1/4 mile racing. I'm trying to squeeze as much hp out of 93 pump as I can get away with. So, is it even worth swapping to 4 bolt mains? At the least, I am going to install ARP main studs down there while I'm getting the block prepped for the stroker kit. Thanks for any tips/advise.

cambirdracing

iTrader: (4)

I have never redrilled a block for 4 bolts. But me and wife built her a 489 (.030 over) for her 71 Camaro and had no issues with it. I makes about 550 and she only turns it about 6500. We are running Brodix Big Brodie oval ports and about 10.5 to 1. Basically we just built it like a 454, with the extra stroke. I would think a 2 bolt BBC will handle 650-750 horse.

pancherj

I spend a lot of time lurking over on Chevelles.com...lots of BBC info over there. I think you will find that the consensus is, no need for 4-bolts at that power level. I think the heads might be a little over kill too. There is a guy over there building stroker using factory oval ports that put out over 600HP. I just built a 496, but nowhere near your power level...I'm jealous!!

Paulster2

iTrader: (1)

The only thing I might consider is going with main studs. Like said, the power level you're looking at should be no issue for a 2-bolt main.

radchevy

iTrader: (4)

The 2 bolt mains are very wide and will give geat support up to 700 hp.
My 464 with oval port heads (ported and for sale) with a 0.660 and 242 @ 50 with 11 to 1 put 700 at the crank. Pure street car O5 power tour.

mrdragster1970

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I've been doing this a long time, with those heads race ready, a decent roller, 12-1
and a 1050 you should be at 800 HP on 110 fuel.
Now when you choke it down and kill the power to run 93 fuel, I have no idea what it will make.
We have built several 477-496's, and they all ran great with that combination.
The tunnel ram made more power with 850's, but a single 1050 still makes ~800 HP.

The main studs, and 4 bolt mains are a great idea, might as well do it right if you can afford it.
The flex is in the middle of the crank, that's why they worry about the middle caps,
and started making the upgrade kit's.

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