Ratchet

Ok guys, here's one. Had a discussion the other day with a friend, who has built some killer engines for cars & boats. In any case, we got into a debate in regards to "cast main caps vs billet caps."

My take - Nodular main caps should be fine (maybe I'd consider studs, since they are not splayed) in most naturally aspirated motors, such as the standard Merlin II block. I would tend to think the split to consider billet caps would most likey be 950-1000 hp mark.

His take - You NEED the splayed billet caps for anything that makes any power (whatever "any" means, especially if he isn't funding it).

Anyways, I typically don't hear of N/A engines failing from a main cap "giving." So, I'd like to ask, what are your thoughts on the cast vs. billet caps ? Here's a link to some of the different block info.

http://www.worldcastings.com/downloa....shtml#bbchevy

Thanks !

WETTE VETTE

Dowel tubes around main studs/bolt holes will also keep the caps from moving. After this is done the motor needs to be align bored. I know of a few 900 HP 8500 RPM drag motors running 2 bolt doweled mains with no trouble. Good main studs of course!! The purpose of the splayed caps is to keep the mains still. I think some splayed cap motors are still doweled for added security. I heard there is now a Merlin III. Anyone know about this block?

dyno

Rachet I'm with you I think its over kill.....I'm a pump gas guy so under 600 hp its way over kill!!!

Ratchet

Heck.........I'm not going to be building anything for a while, but I got into the boat I've always really liked, but I needed to find power for it (31 scarab), and I'm running 425 plus Hp @ 6000 through 2 bolt small blocks with studs, pushing this tank to 70, and the engines previously had almost 400 hours on them. So I think that the block would be plenty strong at say 7-800 or so. Bill Mitchell even uses them on his 632 CI engines (not sure if they have the billet caps or not).

Wette Vette - On the Spec sheet, it indicates that they are dowelled..good point though. I haven't heard anything about the merlin III. Could this maybe be the merlin II race block (billet steel mains) ?

Ratchet

I actually used the engines out of my old boat for this.

jdnca1

I don't think World is building ANY Merlin II's now, my understanding is all NEW production is the Merlin III. I was told this at the Bill Mitchell booth at the PRI show anyway....

Ratchet

Sounds like this could be valid...........Bill Mitchell is one of the the main ditributors for these blocks, I believe. Actually, if you call the "old" world product #, they refer you to Bill Mitchell.

Any more info on this block itself would be greatly appreciated, if anyone has any yet.

blown1500

Bill Mitchel=World Products