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Technically yes.

BUT, see what the Machine shop that is doing the work recommends. They are the ones who must install the caps, drill and tap the block and then line bore the block.
 

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Technically yes.

BUT, see what the Machine shop that is doing the work recommends. They are the ones who must install the caps, drill and tap the block and then line bore the block.

Paul- Which ones do you recommend?
 

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A decent billet splayed cap. The LT1 block doesnt ahve a ton of meat in the webs for a straight 4 bolt cap. The splayed will get the outer bolt threads closer to the side of the block where there is more meat.
Again, see what the machine shop likes, they are the ones who must install and stand behind the work.
 

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Why do you want a 4-bolt setup? IMO this is overkill unless you have 650+ HP.
 

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What if I'm still only making 400hp but doing it at 6500 RPM? I've already spun one bearing. Would 4 bolts keep this from happening again? Admittedly the 1st bearing was in a near stock 180k motor and probablly only saw 6100 rpm and even that only a handful of times.
 

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I'd rather have a 4 bolt over a 2 anytime im gonna mod an engine....also alot of the lt's bearings failed under hard usage when the clearance was less than 0.0018 if ya open it up around 0.0028 you'll be far less prone to spinning another.
 

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I here Pro-mag billet ones are good. I think I will be going with those.
Did you mean Pro-Gram?? I used Pro-Grams in my 383 build. It was more of an insurance than a necessity. A few extra dollars up front can open the options down the road. Build it once and build it right. Like already mentioned, talk to the builder and machine shop to see who and what they recommend. I also wanted to mention that if you do go 4 bolt mains, don't skimp on the studs/bolts to hold them in place!!
 

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Did you mean Pro-Gram?? I used Pro-Grams in my 383 build. It was more of an insurance than a necessity. A few extra dollars up front can open the options down the road. Build it once and build it right. Like already mentioned, talk to the builder and machine shop to see who and what they recommend. I also wanted to mention that if you do go 4 bolt mains, don't skimp on the studs/bolts to hold them in place!!
Yes, sorry about that. cwm3
 

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Discussion Starter · #11 ·
Why do you want a 4-bolt setup? IMO this is overkill unless you have 650+ HP.
I figured better to be safe than sorry. I don't know if later down the line if I were to add a s/c, it'd be nice to have the added insurance.

For now, I'm kinda leaning toward studding the block and leaving it a two bolt.
 

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The necessity for 4-bolt mains depends on the engine rpms and the crank being used. What's the point of getting a perfectly balanced forged crank if it is not going to stay in place? If you are reusing stock crank or getting a low-end Scat/Eagle crank, it is probably an overkill.

I don't think there is anything wrong with straight 4-bolt mains. This is the setup corvettes had from the factory.
 

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Discussion Starter · #13 ·
When I start this motor, I'm going to do it right, so the bottom end will be entirely forged. I want the car to last. So spend the money now, so I wont pay later.

I'd love to find a corvette bare block. The one I have now came out of a 95 TA.

We'll see where I go with it......Money is the deciding factor right now......which SUCKS!!!!

My wallet doesn't go as far as my aspirations do. ;)
 

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When I start this motor, I'm going to do it right, so the bottom end will be entirely forged. I want the car to last. So spend the money now, so I wont pay later.

I'd love to find a corvette bare block. The one I have now came out of a 95 TA.

We'll see where I go with it......Money is the deciding factor right now......which SUCKS!!!!

My wallet doesn't go as far as my aspirations do. ;)
So you're looking at spending over a grand on a good bottom end, but you want to secure it to the block with a set of cheap cast main caps?

Go back and re-read the posts by Area 51, then do what he suggested.
 

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The necessity for 4-bolt mains depends on the engine rpms and the crank being used. What's the point of getting a perfectly balanced forged crank if it is not going to stay in place? If you are reusing stock crank or getting a low-end Scat/Eagle crank, it is probably an overkill.

I don't think there is anything wrong with straight 4-bolt mains. This is the setup corvettes had from the factory.
Diddo, my machinist has done a few 800+hp S/C'd LT1's from stock blocks and he states he has never had a problem with straight 4 bolt mains.

As far as 2 vs 4, sure 4 is better...but there are guys like Mike H running 7000 rpm's and over 550fwhp with 2 bolt mains.

If you are spinning bearings a lot with 400hp at 6500rpm's, i'd look into other problems...I doubt it is because of the strength of the mains caps.
 

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Splayed 4 bolt caps are the only way to go , stock 4 bolt blocks are almost as weak as a 2 bolt , being as it pulls from the weak web area , where as the splayed caps will pull from the much stonger side area of the block.
 

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Or think outside of the box...

I have a two bolt stock block with a girdle in a 377 Twin turbo...

It is alot cheaper and very effective, and my RM is stock block fully studded 2 bolt and hasn't had a problem. 2 Bolt blocks will experience cap walk some where around 500 RHP, a 4 bolt will reduce the walk, but will the stock 4 bolt webbing hold >500 RWHP? I don't know, but I will say I put the 4 bolt LT1 I have into my tow truck thats how much confidence I have in the stock 4 bolt holding high horsepower.

IMO if you want to be sure do a balanced, 4 bolt splayed cap and if they make a girdle for four splayed go for it! You can't have a bottom end that is too strong. If the caps move they will eventually fail, so I say do all you can to keep them in place!
 

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Splayed 4 bolt caps are the only way to go , stock 4 bolt blocks are almost as weak as a 2 bolt , being as it pulls from the weak web area , where as the splayed caps will pull from the much stonger side area of the block.
You'll find a lot of engine builders and machinist that disagree. Not saying that splayed ISN'T better, and if I was starting from scratch I would most certainly go splayed...but there are LOTS of people running very high hp numbers with straight 4 bolt, studded mains and no problems and most engine builders/machinists I have spoken to agree with this.
 

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You'll find a lot of engine builders and machinist that disagree. Not saying that splayed ISN'T better, and if I was starting from scratch I would most certainly go splayed...but there are LOTS of people running very high hp numbers with straight 4 bolt, studded mains and no problems and most engine builders/machinists I have spoken to agree with this.
I think you are backward,,, have you ever looked close at a stock 4 bolt block? All of GM's performance nodular iron replacement small block are all set up for splayed main caps. Guess they don't know any better either.

http://www.jrgmparts.com/GM_Perform...y_Small_B/crate_engines_gm_chevy_small_b.html



They also sell
P/N 14011072
Billet Steel Four-Bolt Main Cap
• Outer holes are angled toward the oil pan rails, tying it to the strongest part of the block for greater strength and reliability in competition engines
• Reduces distortion of the main bearing bores
• Cap is machined from 1010 cold drawn steel, with the Chevy Bowtie insignia laser-etched on top of the cap
• Designed for block with 2.45" main bearings
 

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This is a grossly overdebated topic with no clear answer. Guys interject "info" based on decades old opinions of gen 1 blocks all sorts of stuff.

Then there are guys who swear billet is bad because it wont move the same as the cast block. A hundred different opinions with little to back them up.

Why not just agree 4 bolts is better than 2 BUT that based on setups like Mike Harris's that 2 will do a pretty good job for most of us.

I have not heard of much trouble with either style 4 bolt, hell in an LT1 block the bores will wiggle around before that is a problem anyway.

If doing a full build go ahead and do the conversion if you have the coin, and use what the machinist likes, like Pauly said, that way if you have trouble the machinist will be more likely open minded. If you push a machinist to use a product he doesn't like that WILL be the default cause of any problems down the road.
 
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