I'm running the older model balancer (28oz).
I belive you can use the 50oz one, but whats important is that you use the one that they balanced with the crank or your going to have some real problems.

Duck

<font size=-1>[ This Message was edited by: duckie37 on 1/14/03 1:33am ]</font>

 

28 oz balancer with stock rods and KB pistons. To get it balanced only took some drilling on the crank (none added). 50 oz balancer would make it tougher to balance. So a logical person would surmise 28 oz was used.

 

Bite the bullet - get a balancer with a removable weight and a neutral balance flywheel, then rebalance the assy internally. You won't have to worry about it anymore and I've been told it's actually better for the motor. At the very least, get a balancer that you can swap weights with. If you didn't balance the assy with the damper you planned to use, I'd say you tossed away some cash. I'd never switch balancers or flexplates on a balanced motor, unless it was a certified SFI of the exact same part# from the same manufacturer. Find out what damper they used for the balancing and buy one.

 

He said, "I gave the shop both of them so they could balance it to whichever was easier. I can't remember which it ended up being" so I told him that the 28 should have been easier...

 

Actually it could be either one. On my 393 build up I took the balance shop a brand new 28oz dampner and flex plate along with the crank and other stuff but when I picked it up they had switched to a 50 oz dampner and added weights to the flexplate to match the 50 oz dampner.They said it was easier to balance it with the 50oz. Go figure.

 

The balancer weight would be the same inbalance as the flywheel I would think.
So if the flywheel is 28oz then the balancer would be 28oz. If the flywheel is
50oz then the balancer would be 50oz.

 

Hey Just Jim-
What is your setup? Seems funny the bobweight is so different. Could be something like piston weight. On this 393 with stock rods and KB pistons, the 50 oz balancer and flywheel would have necessitated MORE work. For comparison the KBs weigh about 490 grams. What have you got?

 

My build up used a 3.85 stroke Speedomotive crank,Eagle I beam rods with KB 364 pistons. It was balanced by Speedomotive and they ended up adding Mallory metal to the crank along with the 50oz dampner and modified 157tooth flex plate. Speedomotive told me the balance deal was normal. Later when I went to put the motor together I found the crank was way out on the main and rod journal diameters and stroke causing the pistons to sit about .020 out of the hole but that is another story.Needless to say I wouldn't buy anything again from Speedomotive.

 

Jim,Its sound like you went thru Hell with them. Building a stroker is a challenge and you do need a shop that you can trust. I am shocked that Speed o Motive was such a bear to deal with as they have positioned themselves for years as stroker experts.

 

I've got both the 28 and 50 oz Fluidampners - new, I'm running TRW Forged 302 Flat-tops (.030 over), How can you tell which flexplate is which? We ordered a new one from Pioneer (not SFI - I'm not running over 6k and not anywhere near it on a regular/prolonged basis). I plan on selling the balancer I didn't use when I figure out which one I need.