I disagree with that. If 4 bolt blocks were so strong, the guys at the track would just go to the dealer & get the 4 bolt blocks instead of going thru all the trouble & expense of splaying a 2 bolt block. The angled bolts for the steel caps go into a stronger part of the block to secure the caps. You can believe what you want to believe, but you are going to find a lot of builders who disagree with you.

 

Do they go into a stronger part of the block? hmm... GM designed the block for the outer bolts to go straight down, parallel to the inner bolts, not out towards the pan rails. You really think if two blocks (one splayed, one standard) both used billet caps and studs on all four bolts there would really be a big difference in failure rates? I doubt it.

 

I am using Milodons caps and just to clear up the cost issue, the labor for install and align hone is 350. Total with mains is 550. Here anyways.

 

The machine shop that I used to work at charged ~$600 for a splayed conversion and that included the cost of the caps/studs which is around half of that figure.

Every engine builder has a different opinion on the splayed vs. strait 4 bolt strength issue. In my opinion, the splayed caps are nice but I have never seen any real world tests between the two. Most opinions on the two are based on engineering theory. It would be great to speak to someone with real racing experience on high hp cap failures.

I think that most of the f-body community goes with splayed caps because 2-bolt blocks are alot easier to find than factory 4-bolt LT1 blocks.

Jason

 

Yeah, but they designed the optispark too Like the other guy mentioned, we really don't have enough empirical data to go off of and two bolt blocks are more plentiful, so that's what most of us end up with. I try to limit my destructive testing to head gaskets & pistons

 

Just because they "designed" it that way doesn't mean its stronger dude. They engineer things to handle the power limits the vehicle is going to see, no more! They make thier decisions believe it or not on cost effectiveness, thats how they make money. The vette block is engineered for the purpose it was built for, not for aftermarket modifications to withstand a higher HP combination. To think they would engineer a block to withstand 750 HP when it comes from the factory with say 400 or so is just silly. I believe splayed would be the way to go for any serious high HP/stress application.

 

I run a standard GM 4bolt (vette)block with no block fill! Have never had any problems with bearings or crank. 4 years of 20 +lbs of boost.