Is a 2 bolt 454 block worth building?
 

I've read and read until I see crossed eyed. I know in a car application a studded 2 bolt block can handle close to 1000 hp but these are short bursts down the track, not going 5000 rpm or more for extended lengths of time like in a boat. I'm having a hard time finding some 4 bolt 454 or 427 blocks. I'm sure they're around but people don't want to give them up. I was thinking about a studded 2 bolt block with main cap girdles. Any thoughts, experiences or suggestions would be greatly appreciated!!

In the late 80's Mercury 454 ci 330 HP used a 2-bolt main. The 454 ci 370 HP and 420 HP were 4-bolt. Obviously, Mercury didn't think the 2-bolt was worth the risk. How much will you save with an upgraded 2-bolt vs. a stock 4-bolt? In the scope of the whole project, is it worth the risk?
Ben

I'd much rather have a 4 bolt block, but it's a seemingly hard item to locate. Like I stated, I'm sure people have them, but I feel they are saving them for a rainy day.

Might all work out might not, is it cost savings worth the risk?

https://s.yimg.com/fz/api/res/1.2/tV...5f_gallery.JPG

I picked up a gen vi out of a 97 dump truck. It was a 4 bolt. N not sure if you want to change to the gen vi or not

I'm leaning toward a gen IV because I have intakes and some other parts available to me. But if I should stumble onto some newer blocks I wouldn't pass up a good deal.

I have a gen 5 .030 over for $200 clean it and it's ready for assembly. Intake mkiv, gen 5 gen 6 all the same

Don't I need different heads for a newer block though?

I believe you do but only for the gen v. The gen vi they went back to being able to use the same heads.
Again I'm no expert but that's what I read

I'll have to do some more research. Thanks for all the input.

options
bbc 4 blot blocks and 2 bolt blocks are the same you could either buy after market main caps or gm 4bolt caps and have the block line bored and taped .
i have a gen5 454 block also $350

Thanks for all the help guys. I will let you know my decision shortly.

How much stronger is the 2 bolt with good ARP bolt set?

Mkiv heads go right on use the gen 5/6 head gasket. Gen 6 is the same As a gen 5, just with a roller cam

Ok thanks guys!!

The only difference between the 2 bolt and 4 bolt blocks is the main caps and the steel crank instead of a cast crank. I ALWAYS get 2 bolt blocks and put 4 bolt main caps on. My machine shop drills and fits the 4 bolt caps then align bores for the crank. Never had one come apart even using stock bolts. Besides 2 bolt blocks most people think are junk and will almost give them away.

I run a 450hp 2 bolt mark iv in my boat and never had a issue.

Did you use ARP bolts or studs? How big is your boat?

Thanks

here you go... Gen 6's are all 4 bolt blocks and rollers......

http://www.offshoreonly.com/forums/s...ocks-sale.html

Seaman, what did you do to it to get 450hp, please.

Studs are stronger. Maybe not as strong as 4 bolt but it's closer

I have a 24ft Carrera ss7m the motor is 30 over with 9.5 to 1 comp hydrolic roller cam and lifters edlebrock air gap intake holley 750 carb and I used the stock cast crank,rods, and main cap bolts

I have a 2 bolt studed 383 450 hp turning 6000rpm's no issues

I have been looking around here for a 454 gen 5 or 6 mag core or builder ,real hard to find. If you come across a 454 mag with a cracked block cheap, grab it for the forged rotating assy if nothing else , then go find a tired truck tbi motor and build a contender on the cheap. Once the gen 4 castings dried up and merc fliped over to the current truck based bbc line 4 bolt was the flavor. But mostly with cast rotating assy and pistons that were destined for peanut ports.if you stay with gen 4 for your pans heads ect, a 2 bolt with forged crank is plenty durable for most apps also.