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Post by metalbeast on Sept 2, 2005 16:36:41 GMT -5
As most of you know, I am in the process of getting my parts for a 396 stroker engine. Now all of my internals will be forged so I plan on going with splayed 4 bolt mains. My question is there anyone out there running 2 bolt mains on 383 or 396 LT1 strokers? What kind of power/torque are you putting down?
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Post by jaberwaki on Sept 2, 2005 18:35:44 GMT -5
there are plenty of people that do not step up to the 4 bolt mains, however the 4 bolt is the standered for small block strength... its why when me and the boys went thru bone yards looking for blocks to build up, we always pulled them from trucks  |
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Post by AAron on Sept 2, 2005 19:21:26 GMT -5
you can convert a 2 bolt block to a 4 bolt, and have splayed main caps. nice and stong
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Post by metalbeast on Sept 2, 2005 20:55:01 GMT -5
you can convert a 2 bolt block to a 4 bolt, and have splayed main caps. nice and stong That is exactly what I plan on doing. I wanted to see if anyone was putting down hellacious numbers with just the 2 bolt bottom ends. I talked to my buddy on another forum who said he ran 2 bolt mains in his first 383. He ran consistent 11.5s@120+. |
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Post by AAron on Sept 3, 2005 10:48:18 GMT -5
i have seen a lot of 2 bolt big blocks running some big numbers.
and you gotta thing the old ford small blocks only came with 2 bolt blocks, and they are pretty good.
the big problem you will run into is the block shifting and actually moving and twisting, under high loads and high RPM, a 4 bolt helps to lessen this but it wont eliminate it.
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Post by metalbeast on Sept 5, 2005 12:25:40 GMT -5
i have seen a lot of 2 bolt big blocks running some big numbers. and you gotta thing the old ford small blocks only came with 2 bolt blocks, and they are pretty good. the big problem you will run into is the block shifting and actually moving and twisting, under high loads and high RPM, a 4 bolt helps to lessen this but it wont eliminate it. Some of the Big Block Pontiac motors had 2 bolt mains as well. One of the guys at the gym I work out at has a 73 TA with a 455 SD. We were having this same discussion a couple of weeks ago and he said his 455 had 2 bolt mains. I still think I am going to stick with the 4 bolt splayed mains myself though ;D |
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Post by AAron on Sept 5, 2005 14:10:28 GMT -5
i need to check but the SD pontiac came with 4 bolt mains.
no mater what the '73 TA is bad ass
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Post by '68SuperchargedLT1Camaro on Sept 5, 2005 14:21:14 GMT -5
the big problem you will run into is the block shifting and actually moving and twisting, under high loads and high RPM, a 4 bolt helps to lessen this but it wont eliminate it. This is true. You also want to eliminate the chances that a cap will "walk". You need a good clamp on a cap to avoid this. Main studs help. You can get a much more accurate clamp on a cap with studs. Both of these issues are more a function of RPM than power. If you plan on keeping the RPM's below 6,000, you only need main studs. If you plan on spinning it in the 6,500 RPM neighborhood, and higher, you should go with 4-bolt mains, and use main studs. |
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Post by 94m6hardtopz on Sept 5, 2005 17:17:36 GMT -5
the 2 bolt can work up to probably 450rwhp safely, but after that i wouldnt push my luck. the problem is above that number, you are either going to have more cylinder pressure or more rpm then the 2 bolt caps can hold without starting to etch (i.e. -move around). the lt1 blocks are better then the ford blocks about this, but in a high performance application the 2 bolt mains dont have enough clamping force without some kind of girdle.
i had a non splayed 4 bolt, doweled 302 ford block (boss 302). that was pretty strong. ive seen arguments that splayed caps are stonger and that they arent then regular 4 bolts. the argument that they arent any stronger is based on the fact that most splayed blocks were converted 2 bolt blocks that didnt have enough meat to add the parallel 4 bolt doweled mains. so they had to drill splayed to get into some meat for the threads. just buy looking at it id think the splayed caps would be stronger, but im no expert.
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Post by AAron on Sept 5, 2005 17:21:48 GMT -5
if you wanna go real strong just hard block the bottom 1/3 of the block.
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Post by DocSpeed on Sept 5, 2005 22:54:07 GMT -5
i have seen a lot of 2 bolt big blocks running some big numbers. and you gotta thing the old ford small blocks only came with 2 bolt blocks, and they are pretty good. the big problem you will run into is the block shifting and actually moving and twisting, under high loads and high RPM, a 4 bolt helps to lessen this but it wont eliminate it. The ford 2 bolt blocks (Such as the ones used in windsor engines 289,302,351) use bigger bolts than your typical 2 bolt GM block. I plan on converting the little 4.3L to a 4 bolt block when the time comes. |
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Post by AAron on Sept 5, 2005 23:20:50 GMT -5
have you seen the one that TA performance has it is a replacment for the 3.8L?
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Post by AAron on Sept 5, 2005 23:24:02 GMT -5
never mind i cant find it on their site
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Post by DocSpeed on Sept 5, 2005 23:50:20 GMT -5
have you seen the one that TA performance has it is a replacment for the 3.8L? Is it a pretty stout unit? Send me a link when you find the site. |
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Post by 94m6hardtopz on Sept 5, 2005 23:50:55 GMT -5
i The ford 2 bolt blocks (Such as the ones used in windsor engines 289,302,351) use bigger bolts than your typical 2 bolt GM block. and they will still only hold about 450rwhp(289/302, 500 for 351s) reliably with 2 bolt mains and no girdle. the caps start moving around and etching, no matter if they are studded. they dont have enough clamping force, the windsor (351) block itself is pretty strong but its huge 3" main bearing build a lot of heat because of the high bearing speed and makes them tend to kick bearings out at high rpm and it still starts etching the caps like a 302, but at lower rpm because of the bigger bearings. after you put a girdle on the mains this isnt a problem, then the casting just cracks right up the mains thru the lifter valley. |
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Post by AAron on Sept 6, 2005 10:14:47 GMT -5
oh yeah the fords arent the greatest, i was just using that as an example.
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Post by Fire67 on Sept 6, 2005 10:52:36 GMT -5
I've always been told that 2-bolt LT1's dont have enough meat in the blocks webbing area to add 4-bolt main caps. Either splayed or staight, the thickness of the material being drilled into is not enough...
I could be wrong, thats just what I heard.
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Post by 94m6hardtopz on Sept 6, 2005 12:10:23 GMT -5
I've always been told that 2-bolt LT1's dont have enough meat in the blocks webbing area to add 4-bolt main caps. Either splayed or staight, the thickness of the material being drilled into is not enough... I could be wrong, thats just what I heard. i know of one that has been making 700rwhp with a stock block converted to steel splayed 4 bolt caps for 4 years and is still running strong. |
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Post by metalbeast on Sept 11, 2005 0:13:25 GMT -5
I've always been told that 2-bolt LT1's dont have enough meat in the blocks webbing area to add 4-bolt main caps. Either splayed or staight, the thickness of the material being drilled into is not enough... I could be wrong, thats just what I heard. I know alot of guys that have went with the splayed 4 bolt mains on their 383 LT1s. |
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Post by N20Dave on Sept 26, 2005 16:55:17 GMT -5
I've always been told that 2-bolt LT1's dont have enough meat in the blocks webbing area to add 4-bolt main caps. Either splayed or staight, the thickness of the material being drilled into is not enough... I could be wrong, thats just what I heard. 2 bolt camaro and 4 bolt corvette blocks have the same internal dimensions so I would doubt that statement. However, it is true that the factory LT1 block isn't exactly the strongest performance block. They can be made to live at a failry high number but it depends on things like stroke affecting the bearing loads, type of power adder, block prep, hard blok or not, etc... |
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