350 2 bolt main

[82chevy]

hey guys, roughly how much hp and tq can a stock 350 2 bolt main handle? 400hp? thanks

[werewolfx13]

Its not really about how much hp it can handle as much as what RPM it will be run at..

[1976Scottsdale]

I am not sure what it will handle according to a dyno, but the two best motors I ever built were two bolt main engines and were in pit racing trucks.

[VileZambonie]

There have been many arguments over the strength of the 2 bolt vs the 4 bolt mains over the years.  One is that the 4 bolt main caps have less material and actually become weaker. I just got a 350 4 bolt I was going to use for my latest truck, pulled it apart and 3 of the main caps were cracked. I've never broken a main cap or wiped out a 2 bolt main cap ever. Almost any 400 you'll find is a 2 bolt. The 2 bolt allows you to have splayed main caps srilled and installed. So in my opinion build a 2 bolt main just as much as you would a 4 bolt main. If you are all out pounding on your engine or drag racing find a 2 bolt block and have it machined.

[86 chevy silverado]

I have never taken apart a street motor that had any issues with the mains 2 or 4blt, the cracked mains that Vile have found is new to me. 2 blt blocks in my opinion would be sufficient for most builds. High compression, high RPM, blower/ turbo applications or nitrous motors should have 4blt preferably splayed caps. The theory with stk 4blt format is the extra bolt holes drilled straight into the block (oppose to the splayed that is drilled at an angle away from the mains) weakens the mains web, especially the 400 with larger mains.
This would be more relevant on a race motor.

[VileZambonie]

I should have taken pix but I gave the guy back the 350 since we bartered it I got screwed on that barter so he was supposed to come with his bobcat and do some landscaping behind my garage...never showed  Nice guys finish last remember that! Anyway the 3 mains cracked perfectly along the bolt holes and fit right back together. I could have bought new mains and had it drilled & align bored but why bother for a mild truck motor....

[86 chevy silverado]

"Nice guys finish last remember that!"

Yup, I seem to be a depot for all my friends when they need something, very few do much in return.
The caps actually broke into separate pieces when diassembled? Any indication of excessive heat? I will pay more attention to that area in the future.

[Fordeatinz71]

oh yea man, i know that saying well.  i have been screwed more times than i care to remember because i have been "too nice"...and i still keep doing it because i'm retarded. 

[VileZambonie]

Everyone wants to be your friend when they need their crap fixed... I have one friend who I barter with that definitely makes it worth while. We heated my entire garage, put central air in my house, re-piped and ran a new heating zone in my lower level, the list goes on.... but most of the others take and never give....ahh well....

As far as the mains go in that 350...the truck was used as a work truck it came out of...No loose bolts the bearings looked ok just all cracked caps that fit back together like puzzle pieces. My guess is a weak casting

[79SHORTWIDE]

I've always run 2 bolt blocks--for 20 years! I never had one fail at the mains. The one I am using now (you'll see pictured on this site elsewhere) is a 69-70 2 bolt. My machinist told me it's called a "red block" and HE says it's stronger than a 4 bolt. I dunno. He's the machinist-not me. BUT, I had a few motors (2 bolt) that I'd shift at 6800 RPM and no problems. And I used to run the @*&^% out of them. I'm a big believer in having your engine balanced and using the ARP rod bolts. I've heard that a stock 350 2 bolt would live to between 400-450 hp. As will a cast crank and the old "pink" rods. I think it's more about the machine work.

[Captkaos]

2 bolts are perfectly fine for street use.  I too have seen cracked 4 bolts.  Not that uncommon.  I wouldn't think twice for a street motor and 2 bolts.  If you want more strenght, have it machined for splayed caps.