yes

I stayed at 4.530 but made a drunk decision of going SC.

I hear ya, yeah I didnt think I’d have any sort of a problem from the 598 at 4.600, it was more of apprehension of rebuilds down the road and only having .025 to work with. Dart claims 4.625 max I believe. I kinda thought it would be cool if I could make up in cubes what I would loose in going from aluminum heads 10:1 to iron heads 9.8:1... It’d be real nice to keep it around 750/side..

cool but I dont think I’ve got the pockets for that..

I doubt you'd lose anything. Aluminum itself doesnt flow better than cast iron. The 2/10ths of compression isnt gonna matter. I'd focus on the heads condition and flow. A simple nice valve job, blend etc could be worth as much power as you'd gain with an extra 26 cubic inches if the current valve job sucks. Just had a friends Merlin iron heads over here. Good god , those things are F'cking awful in stock form. The transition from the valve seat into the chamber is horrid. The lips from the throat to the seat is horrid. No backcut on the intake valves, and had a chitty valve job on them. Tons of airflow potential with just a little TLC .

If I had a 572, with good pistons and bores, I'd leave it. If I had to buy a set of pistons, I'd bore it to 4.600 with that Dart block. I wouldnt sweat the head gasket material between the cylinders, especially with iron heads. Theres tons of 4.600 bore engines out there doing fine.

BBC bore spacing is 4.84 so you will end up with .240 between cylinders at 4.600
This is where a 5" bore spacing would pay off. I would love to build nice marine motors at 700"

Thanks Mild, understood. But, for example say my 4.5 bore just needs a hone and no skim; theoretically they have 50ish hrs on them. Why go all the way to 4.600 from 4.500 if were buying new pistons, which we are (current slugs arent the quality I want).. ? Or if a skim is necessary why not go to the next je piston stock size to make a 588? I’m still learning, glad you chimed in; I like reading your posts and threads. Thanks.

Merlin Superblock, 11.625, 4.9 bore spacing...

It really does sound like you’d end up at .300 @ 4.625, no?

What model Iron Eagles do you have? 345's?

One of the benefits of a large bore, besides more cubes, is it helps cylinder head airflow. If you have a head with a 2.30 valve and a chamber designed around a 4.250 bore, taking advantage of unshrouding the valve by pulling back the chamber some is a nice improvement in airflow.