I am in the process of figuring out what route I want to go with my next motor build. I am likely going with a Dart Block. I keep going back and forth on whether to go with aluminum or iron. I am shooting for a 555 in the 750ish range on pump gas.

I would imagine the iron block would likely have less bore distortion (better ring sealing), maybe more durable?, make slightly more power due to it's heat dissipation properties. The aluminum block would be nice to help shed some weight off the front end, help the engine run a little cooler, is repairable....my main concern with it is the durability of day-to-day driving on the street. Does anybody have any experience or opinions?

 

We run Aluminum and Cast Iron blocks in our oval track and RR stuff.....

It's a trade off with the things you mentioned. Ring seal and weight.

At the power level you are shooting for ring seal and durability won't be a problem in the aluminum block if you use the correct ring package.... thinner is better. I would want something like .043/.043/3mm or like the 1.0mm/1.0mm/3.0mm if you can afford it.

Also some Aluminum blocks are better than others.... in the BBC world the cast Aluminum Dart is on the bottom.... Donovan or Brodix would be my first choice for a cast Aluminum BBC. The cast Iron Dart is as good as money can buy.
Will

 

you gotta post pics of this!
Wills giving good advice guy knows his stuff

 

On the BBC S/D platform if WE get to choose the brand of aluminum blocks we NOW go with Mitchell's, then Brodix, then Dart in that order.

Am involved with a 100% street-legal BBC which had a Dart from day-one (about 10 years or so back), this time around after a few very constant issues just went to Brodix. We had no choice in this pick was a customer decision!

This ride makes in the neighborhood of 2000 HP, give or take a couple. It gets driven fairly regularly in our area in the good weather, it also a very popular Drag-Week ride!

The "brand" order which I choose above is based on a number of issues over time with one in particular!

(Add) One important issue with any aluminum casting needs addressing beforehand is about "pinning" the lower main shells to the caps, we do these all the time! Same deal as the "pinned" aluminum rod setup.

Thanks, Gary in N.Y.

P.S. One good feature on the Brodix, the cam brgs come "pinned". If you decide on this brand make absolutely certain to check the concentricity between the main saddles and rear main seal registers. Brodix claims .006"/.007" run-out is "normal". There was one around here just recently with MORE than this number, bad enough to need a major "fix"! Difficult for me to believe on a CNC'd piece??

 

cuisinartvette:
Yeah that was my something I regret a little about my first build, I was never very good at taking time to snap photos of the process...I hope to have some photos this time around. I'm still debating whether I want to build it myself or have it built (leaning more this direction). I am just going to have too much money invested in it to risk doing it myself and screwing up somewhere along the lines.

GOFAST:
The pinning that you are referring to, is this a problem due to distortion in the aluminum block that you would not otherwise have with an iron unit, thus the tight fitting pins to help keep the main caps from shifting? I can see why you would want to pin the caps if that is the case. Do Brodix blocks come with them already pinned or is this a job for a machine shop?

I really want an aluminum block and know that if I build this thing and go with an iron block I will forever "what if" myself to death....I just worry that the block is going to cause me more problems than the weight savings is worth.

 

New Century, CN Blocks, Donovan or Brodix... I wouldn't touch a BM aluminum block unless it was given to me and I was getting free machine work. Let your wallet be your guide here. Really need to see what options they come with... Google Search is your friend and maybe some emails

 

555?
Your going to need a lot of camshaft to get that power on pump gas.
I run a 582 10:5:1 Dart Iron Block RHS Heads. Motor made 816 on 91 octane. Car runs mid 9's with Drag radials and full exhaust.

Steve Schmidt developed the combination. Runs 180 degrees on the street in the Florida heat. I would do a 598 or a 582 to get the power you want with a mild solid roller...

I posted the Dyno numbers here on the forum a year ago. Best street engine Ive ever owned. We plan to switch to a Holley Dominator EFI next year. Still running a Quick Fuel 1050.

Good luck....

 

If you want aluminum then get it, come on thats just badazzery on the st
Let my machinist talk me out of an alum. sbc shouldnt have.
If the machinig and assy is on the money whats to worry about?
Do it!

Love the idea of a big yet light BBC. Lsx what?lol

 

ive got 2-588'' bbc engs,dart pro1 heads,merlin blocks,cola cranks,carillo rods,from carb[1250 dom] to oil pans

fresh ,dyno time only

you couldn't build 1 eng for what I want for the 2

 

Go Alloy! If you don't, you will always be wishing you had! Nothing finer then the reaction when others realize its "All Aluminum" Makes for a quick diet, right where it needs to lose it at...the front.
My 555" D500 Donovan block is going on 11years...and 0 issues. over 300 pass's but I would never use it as a day to day car. Motor made 773 on pump gas.
As nice as your car is, you both really need to go the way Alcoa intended!

Dave

 

Will whats an alll alum long block weigh approx?

Liking this idea all the power sbc type weight?

 

JoeC427:
750 horsepower shouldn't be anything too crazy to get out of a 555 with a nice set of heads and reasonable camshaft it is pretty easily do-able. 700 horsepower isn't that difficult to get out of a 496 with the right heads and cam. 598 or 582? I get lost with some the big stroke and bore combos...is that a tall deck? I really want to stay with a standard deck height and reasonably nice rod/stroke ratio. I want to make power up to the 7000ish RPM range. I like the 4.25" stroke, it has a rod/stroke ratio very close to a 454s so higher revs shouldn't be a problem.

cuisinartvette:
I am almost 100% certain I am going with the aluminum block. In the past I focused too much on just going as fast as I could down the 1/4 mile, I want to improve the handling as well this time around. Shaving like 90lbs off of the front would be pretty significant and will benefit me with both the 1/4 mile and handling. I'm not sure what an all aluminum big block would weigh but I am assuming that it will get me close to the weight of an all cast iron SBC...which is good because I never changed my front springs lol.

dmaxx3500:
What's the reason for selling?

d555
My car isn't a driver, just a summer cruising car with the occasional jaunt down the 1/4 mile. You are correct, I know myself and I will likely forever dwell on the fact that I didn't go the aluminum block route (how often do you ever really buy a block....hopefully not often lol). I think you have me sold on the idea

 

they were supposed to go in an offshore boat and the customer ran out of money