Big cube street Hemi. Iron or Aluminum?

Back story: I went on a short trip to purchase a pair of heads for my Dart. The seller had me surrounded by Hemi. 6 blocks, probably 20 sets of heads, rare stuff all around. So it got my interest up and I started to dive into a research tangent on Hemis. But I can't seem to find the information I am looking for. So I'll ask you.
If you were going to build a big inch street engine(572-605), would you go with an iron block or aluminum? Why? Hydraulic roller, solid roller?Street would entail lots of street miles, trips down the freeway, and possibly a weekly test and tune session here in the weather challenged states.
If you would need an application, let's shoot for 850 horsepower, broad torque curve, heavy car, clutch, 3.23-3.55 gear, likely overdrive.
Yes, this would be my dream build for my Super Bee, but I'm just daydreaming and bench racing. Most importantly, I'm still learning.

For a street engine you need to pay attention to cooling and oiling. Some aluminum blocks won't have provision for internal oil pickup or they might not be drilled for lifter oiling so you really have to be careful about that. Especially if you don't know what you're looking at. The cast iron blocks are usually more street friendly but either can be made to work, you just need to understand what you are dealing with.

Aluminum block for the ability to repair it if anything catastrophic happened. Back when I bought mine, aluminum was my only option b/c the iron blocks weren't available new. The cost was so close it didn't make sense to go w/ an iron block anyway. If these newer iron blocks don't need any major machine work to be useable, then they'll certainly be cheaper b/c the aluminum blocks are more expensive now.
FWIW...the World iron block I have in the shop only needed to be bored/honed and we did a fresh line hone on it b/c I changed the main studs.

I prefer solid rollers. Buy good parts and you won't have any issues.

Got to be aluminium where ever possible!

They are infinitely repairable.

Saw an new iron Barton 572 engine go pop recently and the short motor was Toast.


Met a guy recently with a street KB 500 cube in his Coronet.
Said it drove like the 383 he took out.
Full iron hemi will need big brakes and suspension lol...

Oh yeh, it made twice the horsepower the 383 had and three times if he wants...

Ps, now we know where all the heads are, in Ohio...

Street N/A motor works the best with iron blocks, the rings seal up better and last longer
The expansion rate of iron compared to any alloy aluminum with steel or iron sleeves affect the ring seal and crankcase pressure

We have had a number of both....I prefer the Cast Iron ones. The aluminum ones still suffer from water leakage around the sleeves. You can try and seal them, but you get enough miles on them, they leak, its just a matter of when. Just the expansion and contraction alone is tough to get it sealed & keep it sealed. This is where Steve Morris got the SMX engine dead right....Dry sleeves, and no water passes thru the deck. What an awesome design.

The other thing with the aluminum ones, the bores tend not to be as round. I don't know if its the machining the manufacturers can't get right or if its the amount of material backing the sleeve up. Tool pressure is critical when machining one of these. If the bore is out of round already when you receive it, honing it the last thou isn't going to fix it. Mine had .011 run out and taper in it. If I were to get another aluminum one, I would want to have the thickest sleeve possible and do my own boring and honing.

And the fact that the cast iron one has already turned faster laps than the aluminum one is kinda telling. Would I get another aluminum one, maybe, but I want to measure all the bores first.

The CI one I have now, the bores are real nice and tight with very little taper or run out. Much better clearances. Oil pressure, much better.

But I will probably get flamed either way...To each their own.

For my street car, I went with iron. I think it is a little more forgiving in some ways on the street than aluminum. The weight is a down side, but there are less considerations when driven frequently. As to repairing a damaged block, I personally haven't busted a Hemi block in a street/strip application. At least not yet.

And I have ran Barton's flat solid lifters in my last 2 street engines. Very happy with that decision.

Several good points about using an iron block for a real street car.

Here is one more thing to consider. An iron Hemi block and iron Hemi heads will make the car so front heavy, it will handle worse than it does now.
I do love my '73 Cuda with an iron 440 wedge. But it does handle like crap, IMO. The added weight of Hemi parts ???

Pros and Cons.
The new World (Bill Mitchell Products) aluminum blocks have o-rings around the sleeves.

I'm with you.
Every day class is in session, learning never stops

If you have always wanted a hemi, and a block is available to you...or if you have no problem grabbing one of the Callies blocks that are available now.....my main advice would
be that you really should seize the opportunity as long as the expenditure doesn't cause any stress.
Even if you only have the chance to acquire a good 4.500 bore-capable block and can't do much of anything else for a little while, you should at least get the block.
If it's a good part, and you change your mind later, they hold their value and you can always sell it.
Heading down that road, iron might be easier to sell to street and resto folks (maybe a bigger market), aluminum might be easier to sell to racers.

On my little 572 I went iron block, solid roller, but this is a rather tame engine/I'm sure not expecting anything near 850.
Maybe step it up later, maybe not.
I will wait and see if I get greedy later on and have left myself a little room to sneak up on it.



Solid roller because I just don't trust hydraulics much for 'performance' applications lately. All it takes is a lifter to stick, collapse and a pushrod to pop out to create a very expensive problem. I would rather adjust valve lash than monkey with that.
Iron block because a great deal came along several years ago/I happened to be in the right place at the right time.
Also, it's what I am familiar with so no surprises or huge adjustments to make.

I'd like to try aluminum block someday for weight savings, but if I had to pay today's retail prices...that's simply not going to happen.

I tried to give the whole big inch street hemi situation a push with a build thread, but I think about 8 to 10 people were interested in it, and it was mostly just me talking to myself.

Good luck whatever you decide.

My 2008 KB block has O rings at the bottom of the sleeves. Coolant sealing never been an issue. I also don't believe bore distortion is a problem.

I got my KB hemi block in 2006 (ordered in November '05) and I have yet to have any issues w/ coolant leaks. I have never heard of anyone having coolant leaks from any of the aluminum hemi blocks built in the last 20 years. The only ones I ever heard of having problems were the old versions from the '70s and '80s.
Never had a bore issue either. This last freshen up I had some wear and scratches from hurting 3 pistons (in 2019) from a nitrous issue. The other 5 cylinders were fine...and that's after beating on this thing since I first got it running in August 2006.

Zippy, you need to get a black oil filter on there to make it more color coordinated! The Mopar 409 oil filter is black and easy to find. Or, maybe take a look at the K&P oil filter. It is a screen type filter so you never need to replace it and you can pull it apart to check for junk. They are available with a black anodized finish. https://kandpengineering.com/applications-pricing/automotive/

"An iron Hemi block and iron Hemi heads will make the car so front heavy, it will handle worse than it does now.
I do love my '73 Cuda with an iron 440 wedge. But it does handle like crap, IMO. The added weight of Hemi parts ???"
This is my concern with an all iron Hemi.

I've always wanted one. I have the ability to order an iron block now, or I can wait a little and buy aluminum. The car is almost running again, and it was running well when I broke it. A couple hours and I'm back on the road. So securing a block would likely be the first step in a build that would last a couple years or more. I also have a 340(410?) Dart in line.
I'll look for your build thread, I would really been interested in seeing that. Even though I am not sure I have anything useful to contribute.

Those look really cool and I like the function aspect. Maybe someday.

I had a little paint left in the gun and actually painted about a dozen of those white WIX/CarQuest filters (51068) Mandarin Orange (MP Crate Engine orange).

This filter has only been run 20 minutes or so and is still good!! LOL.
I'm going to cut it open after the next fire up.

Now a couple years down the road, pretty sure I will mask the engine off again and put one more decent coat of paint on it before
I drop it into the car. What I have there is pretty good, but the urethane is a little bit thinner than I'd like.

It should be over in the member's projects section.

The combination of first hemi and first stroker larger than 3.75 was a bit much
to take on at home, but got it done with the help of a couple excellent local machine shops
and advice from friends on Moparts.

One thing you might like:
Some consider this taboo, but one thing I did on that thread was
I provided a list of things that DID NOT work.
I've found this to be a very rare thing, in a world of people struggling, and mostly failing to look cool.
I figure I am always going to fail to look cool, so might as well say something helpful.

it's not a perfect thread but maybe somewhat helpful to you.

Don't be shy with any questions.
Advice is available all over. I went as far back as Bob George's remarks about oiling 20+ years ago/had to thank him, to tagging
Chip and Dave V. on Fakebook to ask what
they thought about this or that detail, to talking to Todd and Dwayne on the phone.

OK, oil filter color has been brought up....
WIX 51515 is black
WIX 51515R is black
NAPA Gold 1515 is black (made by WIX is my understanding)

ive used them both both worked well no problems !!! but the indy aluminum block is about 170 lbs lighter than my old mopar steel block the indy block seems to run a bit cooler on the street also

When I did mine the only option was Indy aluminum. 605, external pick up (previous oil comment), solid roller, pump gas prostreet car. I really like the Milidon pan with integrated pick up. My trans pan sits lower than the oil pan.

IMG_0059 by Greg Ault, on Flickr

IMG_3149 by Greg Ault, on Flickr

what is up with the KB blocks anyone getting them?

That oil pan is a sweet setup. A neighbor just put one on a Dart he built. Has me thinking about using one.

Is that the 31581 pan?

Yep! Milodon says it allows 4.5 stroke. I'm running 4.75 with no issues.

Good deal.

?

Pros and Cons.
The new World (Bill Mitchell Products) aluminum blocks have o-rings around the sleeves. [/quote]

My 2008 KB block has O rings at the bottom of the sleeves. Coolant sealing never been an issue. I also don't believe bore distortion is a problem. [/quote]
I got my KB hemi block in 2006 (ordered in November '05) and I have yet to have any issues w/ coolant leaks. I have never heard of anyone having coolant leaks from any of the aluminum hemi blocks built in the last 20 years. The only ones I ever heard of having problems were the old versions from the '70s and '80s.


I bought my World aluminum block in 2009. The paper work says the O-ring at the bottom of the sleeve is to keep oil out. I have not had any water leakage issues once I found the correct head gaskets for this block.
We have about 15 1/8 mile passes and some street cruising miles, but not hundreds. The cam is a solid roller from Dwayne Porter . The engine is 572 " .
I bought my first 426 Hemi (Iron block) back in 1996 from West Oaks Chrysler in Cali. That was the start I needed to finally build the 426 Hemi I always wanted. I think the MP block was $1700.00 . A good investment as car parts go.

Mark