528 or 472? Siamese or no?

Discussion of Hemi crate engines.

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528 or 472? Siamese or no?

Post by Jess69Charger » Sat Oct 07, 2006 12:34 am

I've heard Siamese bored big blocks (like the 528) overheat a lot, and the cast iron street blocks (like the 472) don't have as much of an overheating problem.

We're converting a 69 Charger to a Hemi RT Clone, we're on a waiting list for the 528, heard about this overheating problem and are now considering the 472 instead. The original plan was to have two four barrel carbs on the 528. Guess we could do that with the 472. But would sure appreciate some input from people who drive these engines.

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Re: 528 or 472? Siamese or no?

Post by hemiragtop » Mon Aug 03, 2015 7:05 pm

I am running a Siamese "mega block" with 4.375 bore/4.5 stroke 540" HEMI. It is in a 4,175lb 66' Coronet Convertible with 3.54 Dana and 727. The engine has a measured 10.78 cr, aluminum heads, two 750 Hollys on a Stage V intake. It dynode at 635 HP with a mild roller cam. I have a STOCK 26" radiator, clutch fan, shroud etc. I run a 180 degree stat and it cruises between 190-200 on the interstate. When I am on a side road (45-55 mph) it cools to 190. This is in the summer with ambient temps up to 106 degrees! Don't worry about the Siamese block, if you follow Ma Mopar's original cooling plan, you will be fine.

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