427 Block s

[bn69stang]

Hopefully this year , sooner than later i will be looking to purchase a 427 block and i thought i would poll you guy s on iron or aluminum , i am wanting at least 500 inchs , all your thoughts and input will appreciated .. Bud

[fairlanegt427]

i have one. it is a pond 482 making 705hp,  i like the motor but a lot of maching money to be spent getting up to spec. all these aftermarket aluminum blocks are just i will call it rough machined.  also this motor takes quite awhile to get up to engine temp.  i had barry R  at survival build it.  i guesss i should ask is what are you gonna do with it?

[CaptCobrajet]

For the street.........one word and three letters............iron BBM.  Can't go wrong at $3295 plus frt.  REALLY nice blocks.

[Joe-JDC]

Most aluminum blocks only go to 4.310 with standard sleeves, but there are optional bore sleeves that are available to go 4.440" but cost more initially.  The new BBM block in iron can go 4.440" and still has good sonic numbers.  If you are looking for cubic inches and less cost, then the iron block is the way to go.  It is more stable, and easier to get all your clearances to stay in tolerance.  I have both, and the real advantage of aluminum is weight--118# vs 250#.  Joe-JDC. 

[fairlanegt427]

i agree with the iron block for the street.  but one thing i did do when i got that pond all aluminum block was i wieghed it with a factory 390 block and it was 93 pounds lighter,  that was just the blocks and nothing else. i new it was lighter but i was not expecting that much. if i had to do it again i wouldnt build another aluminum motor.  it takes a lot of $$$$$$$$.

[fairlanegt427]

i didnt check into the bbm block until tonite.  to be honest if i was to build another aluminum motor that would be the one i would buy.  it is much nicer piece as opposed to my pond block, has better main caps. plus it is quite a bit cheaper than the pond and shelby block by quite a bit.

[MustangGT]

I am using a Shelby alu block on the street. My main reason for this choice was to reduce weight in the front of my Mustang but also because I wanted lotsa cubes so I got their "Big Bore" opion which is 4.375. The stroke is also 4.375 so I got 527 cubes.
Barry R built this engine for me so I cannot tell you what and how much machining was involved.
I love the torque. Very streetable.

[jayb]

That BBM block looks nice, alright, but at 270 pounds its just too heavy.  I like aluminum blocks because you can save 100 pounds over a factory cast iron block (more than that over an aftermarket cast iron block), plus with the replaceable sleeves if you have any engine damage in the bores you can just pop in a new sleeve.  To say nothing, of course, of the repairability of aluminum vs. cast iron.  If my big SOHC engine had been a cast iron block, I can't imagine it would have been fixable.  It is true, though, that the cast iron blocks are more stable; every time I pull apart an aluminum block it needs an align hone to get it back right again.  And the aluminum blocks are more expensive...

[Joe-JDC]

The weight comes down quite a bit when boring out to 4.375 up on the iron.  I thought I saw my shipping invoice with pallet read 250# for a new iron BBM block.  Now I will have to weigh it to get peace of mind.  Maybe start at 4.390" for first build.  Joe-JDC.

[XR7]

I asked Doug at BBM about the weight a couple months ago. He told me 250 pounds. I don't have one to weigh, but it would be interesting to know the exact weight. Maybe the 270# Jay referenced, was a small bore (428) block? Or possibly a shipping weight with pallet? The small bore blocks have a 4.180 bore, for 428 stock and super stock class engines mainly. The cylinders walls are real thick... like well over .400 on a 4.245 bore as delivered, so even more on a small bore. Also I believe it is solid below the freeze plugs, similar to a "short fill", so some weight there, and the thick decks, massive caps... it all adds up. I think the Pond iron and side oiler garage are all around 250 or so as well.

Joe is correct that blocks do shed some weight when boring chips hit the floor. The A460 block is real heavy and when they bore it .125 over it loses some weight big time. I don't know if I would go 4.390 right away, without checking ring availability anyway. I think maybe around 4.375 as you can get a nice ring pack for several bore sizes between 4.375 and 4.400, for future rebuilds, availability can get real spotty after that. Supposedly the max bore is 4.440, but I would start worrying about head gasket sealing between cylinder at that size maybe?


One other thing is, iron blocks will make more power and can go bigger. You won't find any aluminum blocks in Pro Stock, most Comp eliminator engines as well, where budget is not an issue, HP is.

[blykins]

A 4.390" would be a .030" over 460, so I'd say rings are easy to find.  A 4.400" bore is easy as well. 

[jayb]

I asked Doug at BBM about the weight a couple months ago. He told me 250 pounds. I don't have one to weigh, but it would be interesting to know the exact weight. Maybe the 270# Jay referenced, was a small bore (428) block? Or possibly a shipping weight with pallet?

One other thing is, iron blocks will make more power and can go bigger. You won't find any aluminum blocks in Pro Stock, most Comp eliminator engines as well, where budget is not an issue, HP is.

I never weighed a BBM block, and have never seen one in person; somebody who got one just gave me that number.  As far as cast iron vs. aluminum goes for power, I've been hearing that for years but never seen anything definitive on it.  I suppose that would be a tough back to back comparison to make, but I sure would like to see it.  It would have to be due to better ring seal on the cast iron block, right?  And for most people there would have to be enough power in the cast iron block to offset the 100 additional pounds it adds to the car.  That's a lot of power.  Color me just a little skeptical on that one...

[XR7]

A 4.390" would be a .030" over 460, so I'd say rings are easy to find.  A 4.400" bore is easy as well.

Well I am not talking about normal 1/16" ring availability etc. but "thin" steel rings like .043, 1MM, or even .7mm, .030 etc. (if you got the coin).  I'll be honest, I haven't looked into it real deep... but just wanted to mention that it is a good idea to check ring pack availability before ordering pistons and boring blocks I guess. It will be a custom piston anyway, so might as well get a custom ring pack (first).

I know for a 60 over 460 ring, there aren't many options, but at .080 over there are plenty (4.420 and 4.440).

[XR7]

That is what the Pro Stock guys say, is more power from ring seal. They are bore space limited and go as big as they can and a short stroke, so that may come into play as well (wall thickness). I imagine it is only a small HP number, but they are after every little bit at that level. Same in Nascar (iron blocks) but that might be a rules thing, not sure.

I would like to take 100# off my front end, but the extra $1200-1500 additional cost (over a new iron block) would kind of hurt the wallet. I am still running and old beat up 65 FORD center oiler, filled with "grout", so it is a little heavy as well. I have to run an adjustable restrictor under the carb to slow mine down, to be legal at 10.00 seconds. I'm not ready to go through all the NHRA hoops and costs to run in the 9's, but still have done it at several tracks during test-n-tune and/or qualifying, never during eliminations or I'd get the "boot" for sure.

[dwp]

BBM 427 at 4.245 bore weights 257 lbs with caps (caps 20 lbs)
BBM 428 at 4.170 bore weights 262 lbs with caps (caps 20 lbs)