cemittar

At what HP point should you worry about having a 4-bolt main on a 350 small block, with all internals being forged?

bogus

gee... I would think anything over about 450 would be a point of concern.

if you are using forced induction or N2O, I would consider it, too.

I don't remember, did Callaway convert the L98 to a 4 bolt main for the B2K package?

vader86

450+ would be the general areas of concern, RPM would also play a factor.

tpi 421 vette

I have pushed 2 bolt blocks past 500 hp (crank) with ARP main studs. I think you could really get around 550hp safely out of 2 bolt mains. I have heard of guys pushing 600hp out of 2 bolt mains.

wayne lowry

450 horsepower with quality studs and components should be fine. I would be concerned spraying nitrous. If your going to build an engine that's going to put out in excess of 450 horsepower you are going to spend alot of cash so considering the cost involved I would go with a 4 bolt block.

redrose

four-bolt blocks are all over the place for $200 or much less if you dig a little...leave your 2b in one piece while you build the 4b, sell the 2b after change-out and smile

bowtie350_428

Has anyone every seen a ’87 or later 4 bolt block with 1 piece rear main seal and factory roller lifters? I was told that if you want to get a factory 4 bolt main, you will need to go with a pre ‘87 block.

I have always wondered if this was true because that is why I got my ’77 4 bolt block. Can anyone tell me if it is true or was I feed a plate of BS?

bogus

well, do you count the Corvette LT1/LT4? those are all 4 bolt, 1 piece, roller blocks, but they are a little weird.

I am still a fan of machining in the additional bolts... can you say "splayed caps?"

bowtie350_428

I meant Gen1 SBC (non LT1/4) with factory 4 bolt mains. I was told that Gen1 4 bolt mains were no longer produced in 87 or so. Just wondering if that is true?

bogus

I don't know... I wonder about truck blocks?

Bruce Witherspoon

4WD trucks and some HD models are 4 bolt main. I have used both 2 and 4 bolt in drag race motors and like many of the people here have already implied, it depends on the usage. Extended rpm larger displacement,(350 +), applications are where 4 bolt blocks are most important.

Bruce Witherspoon

Hope this helps everyone with there part #s and applications.
http://www.mortec.com/

Blownfuel1

Definitly going to go with Bogus here, why search out a factory 4 Bolt block that isn't much stronger when you could just have your 2 Bolt block machined for splayed caps? That being said, I've built quite a few 4 bolt engines over the years and never had a main bearing web failure, but a lot of people who should know what their talking about (Smokey Yunik among others) claim(ed) they are weaker. I say if you have one, use it. If you don't (and your not trying to save your original motor for any particular reason), definitly look into the splayed cap conversion and see if the added strength is worth the extra cost (Caps, bolt hole machining, and allign boring afterwards - must be done when replacing caps) to you.

cemittar

the original plane was to do that. 4 bolt main cap kits are pretty cheep mail order but the machine shop here for what ever reason decided they are not going to do it any more(machineing line boaring) so other than take the block out of town(closest good machine shop is 100 miles away) I was just wondering if it was at all a "have to have"

boostedmaxPSI

Yes you are correct, Callaway added a 4 bolt main as part of the B2K Twin Turbo and SuperNatural engines.

rodj

Vortec L31 4 bolt block the same as L98 roller.That is what I am using for my race 383 build up

Quiktrp94

I've seen the term "splayed caps" in many posts, but never knew what it meant. Could someone describe what it is? Sorry for the hijack, but didn't want to start another thread for (I hope) a quick answer. Thanks, Robert

MikeC4

I'll post a visual of splayed, but will leave it to the experts to explain...

bogus

those pictures are worth a thousand words...

the angled bolt of the splayed cap will retain the bearing cap better, and the cross bolt, well, gee... that's killer stout. think 427 side oiler.

Quiktrp94

Thanks.