LOL. Thanks! Hampton's and others have recommended a hub. Especially once I told them that this was an internal balance engine. I did quite a bit of reading on this subject and didn't find anything negative about using a hub... That said, I'd be interested in hearing some real world experience. It's not an item that's set in stone as I'm still sourcing parts to drive the blower so it isn't a big deal to change now but one of my goals was keep the belt as close to the front of the engine as possible for clearance reasons. The hub helps quite a bit from what I've measured but I haven't mocked up all the accessories so I'm not sure how it'll play out. I'll be sending the rotating assembly in for balance shortly so need to make a decision here..

Thanks. I'll check it out.

Honestly, I think what I have laying around is off of an older SBC and since its internal balance and bolts up I considered using it but I don't know if it's plain cast or ductile/nodular.... More reason to get something different I suppose...

I have the same memory.

Well, I have no memory..............I think most if not all the OEM Merc's are externally balanced ??.........when I built my 540's the rotator was internal so I had to buy neutral front and rear........

They are Nodular, just replaced one on a Corvette that is part of the collection that I take car of.. Ordered from GM .

I ponied up the 225 bucks for an SFI steel flywheel.
I realize it's probably overkill for a 5600-5800 Rpm, 675 HP engine,
but I bought the peace of mind.

Agreed. I used my stock black motor flywheels and had them balanced to zero and used an SFI front end with internally balanced rotating assy.

Well the good thing is we never seem to build less hp engines and typically go after more so you not only did the right thing for current build, you also set yourself up for down the road.

I have run them in my boats stock gm flywheels never a problem 6500-rpm Than I made some aluminum ones on the Bridgeport.