ZZ4 flywheel

[joe g]

I have a ZZ430 (ZZ4 with fastburn heads and "hot" cam) currently running with a 700R4.; I am looking to convert to a TKO600. I had thought this engine was a one piece seal, external balance, but the flywheels I found in Summit's catalog list the flywheel for a ZZ4 as one peice, internal balance.

Does anyone here know for sure?

[WS6]

It's not balanced by the flywheel if it's externally balanced. I want to say the engine is internally balanced though. I've done a couple ZZ4 cars with muncies behind them and simply used a center force clutch and flywheel designed for a one piece rear main SBC that's supposedly balanced from center force. I haven't had my machine shop verify it's balance and I've never had a problem.

[Lowend]

It I'm not mistaken all 1-piece rear main chevy's are external balance. I believe you want a flywheel from an '88 Camaro 5-speed

[TPI Monte SS]

I'm pretty sure the above posts are correct. The GM P/N for the 153-tooth flywheel you need is 14088646. That's what I used on my old 305, and I re-used it when I swapped in my current 1-piece RMS 355. No issues here!

[TD509EFI]

There are three GM flywheels that can be used with the ZZ430/ZZ4 engines:

14088650 12 3/4" standard weight flywheel

14088646 12 3/4" lightweight nodular iron flywheel

14088648 14" standard weight flywheel

John

[Bill Howell]

I went through this with my ZZ4 in the malibu when I swapped trannys and went with a T56. You have to ad the balance weight to the flywheel. On the on I used (McCloud) it was a simple bolton deal, just added the weight. Holes were already there.
Long story short, you need a externally balanced flywheel.

[WS6]

Well crap maybe I am wrong as it's been a couple years since I did these cars. I'll see if I can remember to look into it next time I am at work.

[TD509EFI]

All one piece seal SBC and BBC are externally balanced from the factory. You could, of course, get the factory or aftermarket crank internally balanced. Since the TKO uses the "standard" diaphram push style clutch, you should be able to use any flywheel thats designed for a one piece seal, externally balanced engine. I looked at the Summit Online catalog, some of those listings are wrong. Decide which clutch / flywheel you wish to use, then check with the manufacturer directly to make sure you get the right part number for you application.

John

[joe g]

Thanks guys.
The GMPP site lists the flywheels that work; it just doesn't identify them as internal or external balance. I think the Summit site's info is incorrect as well as far as the balance. I assume I will need one for a one-piece seal and I should be good to go.
As far as the wheels that allow one to add weight, how would I know how much to add? Where do I get the weights?

Thanks again

[Bill Howell]

McCloud flywheels are pre drilled and threaded for the weights, you simply order the weight and bolt it on.

[recklessnova]

hey the mcloud part number you need is 460260-1a the zz4 eng and other one piece rear main 350 motors are condsidered internally ballanced i just got off the phone with mcloud the only differance is the cranks used in the newer one peice rear main do not have the counter weight its sort of complicated i have the tko 600 in my car and thats what classic and mcloud told me to use
josh

[recklessnova]

found this on ls1 tec maybe that will help more then my babble
The deal is, with the Gen 1 SBCs such as the 305 and 350, part of the balance weight was made onto the flywheel flange of the crank. However, the 1-pc rear main seal system won't go on over that weight; the cranks flange needs to be round (or at least smaller than the seal... duh...). So the weight that used to be part of the crank, had to be moved to the flywheel. The motor technically is still "internal" balance, even though some of the weight LOOKS to the untrained and oversimplifying eye, as if it's "external" to the motor.