Merlin II vs Merlin II race, and Merlin Pro Blocks
 

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 !

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?

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

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) ?

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

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....

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.

Bill Mitchel=World Products