Some block advice needed...

Hi guys... Fantastic site. Glad I stumbled on it while looking for something else on google.

Since there's so many other blown enthusiasts here, I have a question on blocks for BBC.

Up until recently I was running a .100 over (4.350" bore) 427 block with a 4.25" stroke crank (505 CID). 10.2 deck height. Block was 1/2 filled.

The internals were pretty stout. Oliver Rods, Cola 4340 crank, j/e pistons, Ultradyne cam (.735/.725), with a 10-71 Mooneyham (triple stripped) and an enderle.

12.5:1 compression, with 24 lbs of blower boost.

Based on et and vehicle weight, we're figuring it made about 1400 crank hp.

Unfortunately, we had a backfire which bent a rod and cracked a cylinder.

So, I'm at a crossroads. The cost differential is insignificant (about 300.00 difference)...

Which block? Bowtie (~$2100.00) or Dart/Merlin (~$2400.00) Is there any advantages from one to the other?

I thank you for your input.

-WJ

 

No question, get the Dart. It's heavier than the Bowtie or Merlin but the walls and decks are thicker and you can get away without filling it. Even if your talking the MKV Bowtie, the Dart is a better foundation. Don't waste the money on a MKIV for your application.

 

Why not just sleeve the hurt cylinder,..$200-$300

 

Well, we had considered that. But with a 4.25 bore already at +.100 over, installing a press fit sleeve will cause a couple of problems (as we see it).

1. It'll distort the block slightly, which could cause other failures.

2. I'll have to rehone the block, which could cause piston to wall tolerance issues (too loose).

It's a tall deck garbage truck 427. Making 1400 HP is probably stressing it beyond it's intended limits a bit. It's time to step up as far as I'm concerned to something that's going to not be pushed so close to it's limits.

BlownAlky;

Of the Bowtie blocks, we were considering the new Gen6 Bowtie, which at a 4.6 bore, GM *claims* to still have .250" cylinder wall thickness. Deck thickness I believe is .600".

The Dart/Merlin specs on their website both claim to have .250" at 4.6 bore and .600" deck thickness.

I guess where my concerns come in, considering all 3 companies claim to have the same tolerances are....

1. Who does a better job with their machine work.
2. Who does a better job in correcting casting issues that arrive after blocks have been on the market.
3. Who uses better castings from the standpoint of less core shift, denser material, etc.

Thanks for reading and any input.

-WJ

 

Save your pennies and buy an aluminum block. It's money well spent. If you hurt it ,it can be fixed a lot easier than a cast iron block and a lot cheaper.
Just my .02 worth

 

block

I agree with Bob go with an alum. block. A little more $ but easy to repair and a whole lot lighter. I use and recommend the New Century block its cross bolted and very close to a K.B. block. A whole lot cheaper than the billet blocks too. Regards Jody Stroud

 

Well, while that sounds good and dandy, I see a couple of issues.
1. I could probably buy 2 iron blocks for the price of 1 aluminum.
2. It'd look pretty stupid, and I don't know if it could even be done, running iron heads on an aluminum block.
I don't care to build an entire new motor. If I did, I'd wind up going to a larger bore, necessitating new, longer rods, new pistons, bigger blower, the list goes on. Which means I'd be better off just scrapping and selling everything I have in this motor minus the crank, Buzzard catcher and nitro style valve, lol.

*edit* Sorry for my ignorance, I've heard of New Century before, but I can't seem to find their website. Do you have a link?

 

Here you go:
http://newcenturyperformance.com/Index.htm
Dave Koehler

 

That's the ultimate way to go if you have the $$$, the New Century is within reason and would be the best besides the CN billet. The issue is that you will have to get a +.250 gear drive or belt drive with this combo and a different oil pan, all at added cost. If weight is not a problem, the cast iron is an economical way to go. The Dart block has a .300 wall at 4.625 so in your case your will have plenty of wall. On the down side, you will have to bore & hone it, deck it and line hone it when you stud the mains. Here is the link: http://www.dartheads.com/manager/uploads/tech - Big M Iron Big Block.pdf
Again, the Dart block is heavy. It is heavier than a filled stock block but it is much stronger. If you have an extra 2k to spend, you can buy your block from LSM (http://www.lsmeng.com/) and have them lighten it and get closer to the weight of the Aluminum block. All it takes is cubic $$$$'s, how fast did you want to go?

 

Yeah, honestly guys, if I had the cash, I'd build a totally new motor, around 572 CID, with a hi-helix 1471. But, for all intent and purposes, I don't see needing to go over 2k HP for what I want to do. The Iron blocks should be able to take care of those needs quite fine. Now, if I wanted to build a rail and come play in the TAD class, sure.... But, my fun budget doesn't allow for that at this point.

Sounds like the Dart is the way to go over the Merlin/Bowtie (from the two responses relating to iron blocks).

-WJ

 

I would not worry about running a iron head w/ aluminum block, as when the Rodeck 481 hit the market ~1977, it was seveal years before a compatible aluminum head was available. You can upgrade heads later.