BBC Dart big M power handling ability

We have a Dart big M deal what is the power handling capabilities of this block ? We have a 11.5:1 PSI D screw 38-40 psi turning 84-8500. I figure it's making near 2400. We ass holed # 2&3 main bearings. The others look fine other than the trash going trough them. The rods are fine other than the trash tracks. I talked with Dart and they said that's too much for the block. The problem is I have 2 of everything it takes to have 2 engines. I was thinking about opening the mains up to .004 from .003. To help the problem. I figure I'm Pissing in the wind... Any input or experiences welcome !! Thanks Craig

 

Doesn't Steve Morris use them for like 3,000 hp ?

 

We have 4 of those blocks and first started with them years ago.

I would expect it to be fine, with that being said there are many ways to hurt engines.

Are you running a crank snout support and is your clutch in really good shape? The 2 major things we had to help our mains.

The only other thing I can think of is oil restricters, we run them and most don't. I've never tried without to see if the mains are hurting because of less oil. Do you run oil restricters?

 

Bbc

I would look hard at the oil system. No room for error on a Chevy esp wet sump.

 

I would run .0045 to .005 60 wt oil 100 psi plus oil pressure !!!!!! .003 is way to tight for a boosted engine

i ran a iron dart block in a 2000 hp SBC with no issues

 

No clutch it's a jet boat. We were running .003 and looking at .004-5 so things can move around. Thank you !! Yes we have a support. No problems on 1'2 or the rear main just 3 and 4 mains. We had a wiring problem and it shut off 3 times on one pass. I figure that is what done the damage. Just wanted to throw it out there. It ran out 3 seconds died came back died then came back. I figure that did the deed. I just wanted to get some input so I could wrap my head around it. Thank you !!

 

I ran Merlin and Bowtie iron blocks (540 with 14's at about 30 pounds) and never had an issue with main or rod bearings. I've ran with restrictors and without in back. I always have the rotating assemblies balanced. We did find the limit on the Bowtie after about 10 years. They split real nice from the main web right up through the cam journals!!!! JW

 

Oh, and yes--lots of clearance! JW

 

Ok no clutch, but is there anything else back there (I'm not familiar with boats) that could be out of balance. If you aren't hurting #5 this is probably not an issue for you.

The other thing I thought of is if your main journal is no longer round. We had that a couple years ago, that crank was .0003-.0004 out of round and the main bearings would only last about 3 runs.

We run .0035-.0040 with 50 weight

Any chance the main bores are not round anymore, we were bending 2, 3 & 4 main caps for a while which of course made the bore go oblong.

 

Billet or cast caps?

 

Billet with studs.

 

Ive ran that block that hard plenty of times and would agree the intermittent shut off probably caused the drama, but definitely open up those oil clearances .004-.005 with 50-60wt oil

 

Yes on the restricters they are .090 each.