I have a a Hemi block but is it the right one for me?

Im trying to figure out what to do so I figured I would start here.

I have a new, never built, pre World 4.500 Hemi block. I don’t know if I should build a street friendly 528ci or try and find a 4.250 water block and build a 472ci. It’s going into a 1968 Super Stock Barracuda clone that will be street driven. I’m looking to make 550hp so do I build a siamese bore engine and hope I can keep it cool or trade it to somebody with a new water block and not worrie about over heating it?

Its the same price to build a 426 as a 572, so go with the 4.5 stroke crank and have more than enough power to do anything you want. I did...and cooling is not a problem with a big enough radiator.

I’ve got a bud who bought a 528 Arruza hemi. It was a pre world block. I’m not sure I remember the specs but I pretty sure it was a 4.25 bore originally. I think he went with a .100 over bore and a 4.25 crank. I’m too lazy to dig up a website and do the math but I think that was it. You can still use the internal oil pickup with a 4.25 stroke. He has no trouble with heat problems even in Texas. He has a roller cam that is way too big or he would drive it more often.

Troy, I've built a few siamese Hemis, no cooling issues at all. Used a new 3 core rad, original shroud, old mopar clutch fan and correct pulleys on all. Building another right now for my Hemi Dart, will be the next power tour cruiser.

Some good info here. Part of me says just build a 528 and be done with it. Another part of me says if someone is looking to trade a 4.500 siamese block for a water block then I can make two people happy. I can’t go with a big radiator because I need a Stock looking rad.

550HP is pretty easy even at around 426CI; my 438" Street Hemi made 540 with old cam technology.
More cubes means of course that it can be tamer at that power level. At 528" I'd think it'd be hard to NOT make well over 600HP.

US radiators 3 or 4 row optima copper brass, tripple pass looks factory, just get it in 26"

I can't think of a reason not to build the siamese block. Use a 7.1 rod with GM ends (2.2/.990). On the street...it will live forever if it's done right. GM ends let you buy a more common rod/bearing, plus it takes a little weight out of the already heavy Hemi rotating assembly. Go bigger if you can, usually very little cost difference between a 528-540-572" combo.

Thanks for all the feedback.

These Hemi Darts and Barracudas left the factory with 22” radiators so a 26” is not the look I’m going for.

The 472 in my Dart is making 530hp and that is just fine for what I’m doing. My cars still have the factory 6” wide wheels so it’s not like I can even use the HP that I’m making.


In a nutshell I’m looking to trade a new 4.500 Hemi block for a new 4.250 water block. I know somebody out there could benefit from this.

Not sure if you'll be able to find a trade or not but you shouldn't have any problem selling that block and then using the cash to buy what you want. You might want to call around and see what you can find. Mazzolini, FHO, Barton, etc. Someone might have what you want sitting in the back corner.

Hi Andy, good idea. I will start that soon. Thanks

Troy, I think I might have the block you want. Pre-World, new 4.250 water block. Never assembled. Unfortunately, we are on opposite sides of the country but I am very open to figuring sonething out. Let me know if you are interested.

Stan

I would go with the 528" option. My 528 Hemi is a 10.5 pump gas street engine & knocking on the door of four digit horsepower numbers on motor only. I still have two additional NOS foggers plumbed on it also just in case I am late for work....

I have still not heard why you wont do a 572...go big or go home. ITs the same money and less stress on the motor for the same power.

get a quote from Fastenal for shipping if you strike a deal!

Good question. There are several reasons why I don’t want a 572. My 472 already has more HP than the tires can handle. I’m building the same package but now in a Barracuda. I don’t want or need 650hp out of a 572. A 472ci would work better for me. Bigger is not always better. These are the tires that will be the car. Would you want to put 650hp to these tires??LOL!! I don’t think so. 😋

Thanks for the reply, Troy

I built a 472, a 528 and installed a 572 in my Buddys Cuda. I really liked the 472 combo. It made all the power a street tire car could handle and the fuel mileage was better too. I find the 472 to really be a good combo and the block is lighter as well. Another benefit is that I ran unported Stage V heads on the 472 and it seems to be a balanced combination, so you can save money on porting. Although I guess if building a bigger cube engine you could run the Edelbrocks unported as well.
I think the big cube thing is more an ego thing. I see lots of big cube engines idling into the cars and coffee deals, these cars never run slicks.