Switching from flexplate to flywheel...balance engine?

[tiznodd]

I'm in the process of converting my 67 camaro from an automatic to a T56. I recently purchased a Mcleod street twin with an aluminum flywheel thinking it would simply bolt in place of my flexplate. Long story short, after speaking with the folks who built my engine, they tell me that the flywheel must be balanced to the engine since it's an externally balanced engine. They said you could take the flexplate and try to match the flywheel to it, but that it wasn't really a good idea. They suggested I tear the shortblock down and have the rotating assembly balanced with the new flywheel. Does anyone have any experience with simply matching the flywheel with the flexplate to avoid opening up my engine? It's an old LS6 454 that was rebuilt about 1k miles ago. I shift it at 7200 if that makes any difference in how accurate the balance must be.

Thanks,
Todd

[HILROD]

I have done this in the past, never had any trouble. It would be no worse than just changing out a flywheel when doing a clutch job. Some engine builders balance with the flexplate attached, that's fine if there is never a problem with it. You shouldn't have any worries as long as you use a quality flywheel and clutch. The better name brands are all balanced, some as a matched set.

[Adam's 55 Chevy]

I have done this in the past, never had any trouble. It would be no worse than just changing out a flywheel when doing a clutch job. Some engine builders balance with the flexplate attached, that's fine if there is never a problem with it. You shouldn't have any worries as long as you use a quality flywheel and clutch. The better name brands are all balanced, some as a matched set.

X2.

[Texas Hotrod]

I've seen balance plates used for externally balanced engines (SB400/BB454) when a "neutral" flywheel is used.
You might see what Jegs/Summit has.
Machine shops usually finagle the internal weight when balancing an external engine. That way there won't be issues when changing to different external balancers and flywheels.
No use ruining a good flywheel.

[tiznodd]

Thanks for the replies. My machine shop drilled into the flexplate weights when balancing the engine the first time, which made things more complex. Having said that, they were able to balance the new flywheel to the old flexplate, but unfortunatly had to drill into my pretty new aluminum flywheel to balance it. I've been told that drilling into the weight isn't the right way to do things, but since this was the way it was originally done, I had no choice but to let them drill my new one.

[Adam's 55 Chevy]

I would just dress any drill holes to gently radius them and get them smooth so no stress risers or cracks occur. A drilled hole may look smooth but it isn't.

[LS6 Tommy]

Is there any particular reason you chose an aluminunm flywheel? What is your intended use of the car? You may find it's harder to keep it out of the rev limiter & it can be annoying for street driving, especially with a "grabby" clutch. It'll also really soften your launch if you're drag racing.

Tommy

[tiznodd]

I don't commute in this thing and seldom take it out when there is anyone on the road. It is strictly a toy. I don't care about drag racing it. If I take it to the strip, all I really care about is mph. I'd like to start road racing it at some point. I think the aluminum flywheel will also be easier on the drivetrain when I slam gears.
One of my reasons for getting an aluminum wheel was based on Mcleod's recommendation. They seemed to think with an almost 500 inch engine, the driveability loss of the aluminum wheel wouldn't be as noticeable. They also assured me that there is a noticeable difference once you are into the rpms. Hopefully I made the right choice.