2 bolt Main, 4 Bolt Main... what is this?
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2 bolt Main, 4 Bolt Main... what is this? I know Camaro LT1's had the 2 bolt main and the Corvettes had the 4's. What the hell is a main? 
Anyone able to give me some good links so i can understand what a 2 bolt main is as compared to a 4 bolt main?
Anyone able to give me some good links so i can understand what a 2 bolt main is as compared to a 4 bolt main?
Originally Posted by TobyZ28
I know Camaro LT1's had the 2 bolt main and the Corvettes had the 4's. What the hell is a main? Anyone able to give me some good links so i can understand what a 2 bolt main is as compared to a 4 bolt main?
Anyone able to give me some good links so i can understand what a 2 bolt main is as compared to a 4 bolt main?The mains are the caps that cover the crank bearings. The number of bolts that holds the end cap mains is 2 for a 2 bolt main and 4 for a 4 bolt main.
When you pull the pan you will see the main caps holding the crank in place. A two bolt block will have a blot on each side of the cap, and a four bolt will have two on each side. We like to use the two bolt main blocks so we can install a splayed 4 bolt cap. On a splayed cap, the inside bolt goes straight down, and the out side bolt is at an angle. Makes for a much stronger piece.
Originally Posted by KJ@SDPC
When you pull the pan you will see the main caps holding the crank in place. A two bolt block will have a blot on each side of the cap, and a four bolt will have two on each side. We like to use the two bolt main blocks so we can install a splayed 4 bolt cap. On a splayed cap, the inside bolt goes straight down, and the out side bolt is at an angle. Makes for a much stronger piece.
Originally Posted by wickedwarlock
wow, learn something new everyday. I never heard of the splayed cap. Sounds interesting. I would love to see some pictures of that.
www.milodon.com
Originally Posted by Casper97
In my opinion, a two bolt main ain't any stronger than a four bolt main if it ain't splayed. That makes a huge difference!!!
a two bolt main is not supposed to be stronger then a four bolt. I have my studded my 2 bolt dont know how it compares to a 4 bolt but has held together for me.
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Teching In
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From: Gainesville Fl
Actually a two bolt block is stronger than a four bolt block becuase it has less drilling into the main webbing of the block. The fasteners really are the limiting factor in strength. I prefer two bolts with high quality main studs. Never had one fail, (yet).
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From: LT1 land...the "409" of the 90s!
My biggest concern is not how many bolts hold the caps on...but the cast iron caps 
I am in the prosess of converting mine to four bolt mains but only for the stronger caps. Then again I am rocking the bottom of the block to
Probably not going to make as much as John here. the plan is for 550 and then a 200 shot.
I just want the bottom end to hold together and the head gaskets to be the relief valve
I am in the prosess of converting mine to four bolt mains but only for the stronger caps. Then again I am rocking the bottom of the block to
Probably not going to make as much as John here. the plan is for 550 and then a 200 shot.
I just want the bottom end to hold together and the head gaskets to be the relief valve
TECH Apprentice
Joined: Mar 2004
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From: Texas
We, who is we john? You know you have a 6 bolt main in that ls right. I guess that is real weak compared to a two bolt. No I am not gonna get smart ***. Your ls block is actually shaped different than ours so I ain't gonna talk crap. I wonder why drag cars and nascar cars run 4 bolt splayed?
Originally Posted by Casper97
We, who is we john? You know you have a 6 bolt main in that ls right. I guess that is real weak compared to a two bolt. No I am not gonna get smart ***. Your ls block is actually shaped different than ours so I ain't gonna talk crap. I wonder why drag cars and nascar cars run 4 bolt splayed?
so yea, i am pretty damn sure this is a 2 bolt main LT1 bro. my hands put it together. long story short. 383 all forged Lunati motor, canfield head, cam motion/FMS cam, FMS tuned, 13 psi S- trim aftercooled, 100 nos wet shot, blah blah blah. since this is an LS1 mainly site i only put a pic of the LS1 in my sig. so yea, go home.
Last edited by gator's 99TA; Sep 19, 2004 at 05:07 PM.
TECH Apprentice
Joined: Mar 2004
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From: Texas
Nice build. Just one question. Which is a stronger set-up, 4 bolt main splayed, even though you might not need them, or a 2 bolt main? I understand that there is more meat on the bottom end of the block but I always thought the 4 bolt splayed was stronger. Was I wrong???
Originally Posted by Casper97
In my opinion, a two bolt main ain't any stronger than a four bolt main if it ain't splayed. That makes a huge difference!!!
For all that goes, you don't need the splayed unless you are making crazy horsepower. My 2 bolt is together and I laid down 561 rwtq through it.
Originally Posted by Casper97
That is biatchin!!! I bet you keep pushing and you will be in the 10 sec club.
http://www.nhra.com/tech_specs/altitude.html
that's 10s for sure in the rear world (track). Those calculators are always off.
He's already there. Just seen noticed this.
NOTE: Supercharged and/or turbocharged cars (i.e.: AA/A, AA/AT, BB/A, BB/AT, A/PM and AA/PM) use half factor; TA/D and TA/FC cars are not factored.
