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Discussion Starter · #1 ·
before you guys say i'm crazy, hear me out...

would building a 383 out of a 350 2-bolt main block be worth it? I'm not an engine builder, but had always heard 2-bolt blocks weren't worth much of a damn, and those that did use them, turned them into 4-bolt mains. I recently purchased a budget tow rig with a 350. I had thought it was a 4 bolt main and planned on rebuilding it into a 383 (motor needs a rebuild anyway). but tore into it this past weekend and alas, its a 2 bolt main.

so where do i go from here? find a 4 bolt main block? turn the 2 bolt into a 4 bolt ($$$)? or continue the rebuild with the 2 bolt (cheapest)? Now, i really didn't consider the last to be an option until recently i talked with a friend of mine who works for RCR as an engine builder and someone i consider knowledgable. He said, for turing it into a 383 stroker, 2 bolt main isn't gonna make much of a noticable difference. He said the longer rod length i'll get from the stroker crank, makes for better rod angles which alleviates stress at the caps. He said he wouldn't feel bad at all about stroking a 2-bolt 350.

So, being thats its the first time i've heard this and i don't have a lot of engine knowledge, i thought i'd do some more research and run this by the POR guys. can anyone give me any opinions?

-Rob
 

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I know some engine builders would rather start with a 2 bolt main and fit 4 bolt main caps to the midle 3 caps than start with a 4 bolt main block.
 

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Discussion Starter · #3 ·
Yea, i hear a 2 bolt main running 4 bolt caps is stronger than a 4 bolt main factory, but it seems like this would run a few bills at the machine shop to get done (though i actually haven't called yet). I'm trying to stay on the cheap side of things with this project but strong/reliable enough build to get my rig to the trail and back.

-Rob
 

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I've been down this road before when I was researching an engine build-up. You'll hear a lot of opinions, but the real experts will tell you that below 7,000 rpm, a 2-bolt block is fine. And even then, it's stronger to machine a 2-bolt block for splayed 4-bolt caps than to use a factory 4-bolt block. A lot of people have the mind set that a 2-bolt block is boat anchor material, which can be a good thing for the smart buyer.

The engine I built was a 434 CID small block Chevy (4" stroke). I used a '72 2-bolt 400 block and put it through three years of mud drag racing. Never a problem. Now the engine is in a Modified stock car. Modified stock - isn't that an oxymoron??:D
 

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Well, before we go turning our 2-bolt 350's into boat anchors, consider this. Every carbed 350 (and probably all the injected ones) ever put in a pickup is a 2-bolt. Every friggin' one. 350 or 400-powered Blazer? 2-bolt. Most cars? 2-bolt. And I've seen plenty of them zinging at 7 grand with nitrous stuffed in there, with no ill results.

In other words, you're fine.

TEX

PS Postal, I'm a big fan of 434's for mud racing. Guy out of Decatur, IL with one is running below 3 seconds with a Super Stock truck at my events :)
 

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Discussion Starter · #6 ·
TEX said:
Every carbed 350 ever put in a pickup is a 2-bolt. Every friggin' one.
Are you sure? :confused: I thought quite the opposite... It was my understanding the majority of trucks with 350s were 4-bolt mains and 2 bolt 350s were found in cars. If what you say is true, what did the 4 bolts come in?

-Rob
 

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My '70 K5 came with a 4 bolt main 350 sbc.
 

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RodeoRob said:


Are you sure? :confused: I thought quite the opposite... It was my understanding the majority of trucks with 350s were 4-bolt mains and 2 bolt 350s were found in cars. If what you say is true, what did the 4 bolts come in?

-Rob
4-bolt 350's were used in performance applications like LT1's, etc - think Z28 or Corvette, not K10. Maybe a few slid into something old like a '70 K5, then again maybe it was swapped in at some point. They were definitely not used in the newer trucks. 4-bolt 400's were pretty much limited to 2-barrel Impalas. And NONE were made after '71 for any application.

TEX
 

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TEX said:


4-bolt 350's were used in performance applications like LT1's, etc - think Z28 or Corvette, not K10. Maybe a few slid into something old like a '70 K5, then again maybe it was swapped in at some point. They were definitely not used in the newer trucks. 4-bolt 400's were pretty much limited to 2-barrel Impalas. And NONE were made after '71 for any application.

TEX
The early '70's chevy trucks came factory with 4 bolt main motors. My '70 K5 started life as a 9.5 compression rate 350 with 4 bolt mains. You need to go look at the spec sheets for that era before making these blanket statements. :flipoff2:
 

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TEX said:
Well, before we go turning our 2-bolt 350's into boat anchors, consider this. Every carbed 350 (and probably all the injected ones) ever put in a pickup is a 2-bolt. Every friggin' one. 350 or 400-powered Blazer? 2-bolt. Most cars? 2-bolt. And I've seen plenty of them zinging at 7 grand with nitrous stuffed in there, with no ill results.

In other words, you're fine.

TEX

PS Postal, I'm a big fan of 434's for mud racing. Guy out of Decatur, IL with one is running below 3 seconds with a Super Stock truck at my events :)
There were 4-bolts in some of the heavier duty trucks. I had a '78 K20 with 4-bolt 350. I can only assume it was factory, it had 43,000 miles when I got it.:confused:

I know Wilbers well. Used to race with them a lot. Great people. Love seeing that small block truck kick big block butt. Remember Mighty Mouse?
 

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TEX said:
Every carbed 350 (and probably all the injected ones) ever put in a pickup is a 2-bolt.
I've seen 4 bolts in pickups before

also my bros 86 carbed 350 is a 4 bolt

neighbours 350 in his 79 van is also a 4 bolt
 

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Chief yelling alot said:


I've seen 4 bolts in pickups before

also my bros 86 carbed 350 is a 4 bolt

neighbours 350 in his 79 van is also a 4 bolt
Yeah, but Lord knows what other kinda goofy shiat the Canada-Spec trucks came with. :flipoff2:

Pete
 
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