Ok. Im working on a 385 stroker LT1 with .040 bore. My Crank is a Cast Eagle crank and it is Externally Balance and I have 6inch rods. Heres my challange question. Im aware of Externally balanced cranks requires a 400 Damper and a 400 flexplate. Is there a way that I can use my stock Damper and have weight added to the damper to make it equal a 400 damper. For example welding some metal onto it. Im using the Madman Relocation ALT
Bracket.

The other possible way that I was thinking was to buy a 400 damper and have a pulley attached to the front of it. The only thing is im using the Madman Relocation Bracket and I know it is suppose to be used with a stock Damper. So Im wondering if I can adjust the brackets to make it align with the added pulley.
Thanks
Chris

 

If Eagle balanced the crank, it should be setup for a stock LT1 balancer and flexplate/flywheel (assuming you specified it was for an LT1). If it's not been balanced yet, take it to the machine shop and have them balance it to work with the balancer and flexplate/flywheel you are going to use.

 

I dont have the money right now to get the crank balanced. When I bought the crank I was told Externally balanced crank (3.75) I have bought the 400 flex plate so I would prefer not to go the whole balancing route. Also If my crank was internal balance I would see some metal taken out of the crank right? like some wholes or something.
Chris

 

An externally balanced LT1 uses a neutral balanced harmonic damper, and a counter-weighted flexplate. And you're saying the rotating assembly was not balanced???

 

It sounds like you are SOL. The RA either needs to be neutral balanced or balanced against a specific external weight. IF the crank was machined to balance with a specific bob weight and a specific external balance, AND your pistons/rings/rods match that bob weight, then and only then can you bolt up a specific amount of external weight and have it come anywhere close. It won't be perfect, but it would be close. Otherwise, you need your specific combination of parts balanced, whether they are internally or externally balanced.

Rich

 

Ok Im freaking CONFUSED. I thought if you have a Externally Balanced Crank. You must use a 400 Flexplate and a 400 Damper. I though that did not require balancing because you have the bigger flex plate nad damper. IF I have to still get the Crank balanced then the hell with the 400 flex plate and Damper I might as well just balanced the whole damn thing. Man sorry guys im getting so uptight on this whole thing. My car has been sitting for ever and a day. I started putting this thing togather. Im just lost.
Chris

 

The internal parts still need to be balanced against the amount of balance weight on the flexplate and damper. There are a couple of reasons to do this. Some cranks are specifically designed for external balancing and it would take a crap load of mallory. In that case, it's much cheaper to balance externally. That's typically why it's done. Nothing wrong with it. But it will only work in your case IF the internal parts have been selected/modified to balance against the specific amount of weight in your flexplate/damper. Got it?

Rich

 

Typically, LT cranks (OEM and after-market) on the front are internally balanced (neutral) and always use a "dampner" on the front (not a harmonic balancer).

That said, the rear of the crank has two balance options. 1. The OEM factory LT configuration uses a flexplate/flywheel "with" counter-weight (externally balanced), or 2. The after-market (common to rebuilds) uses an internally (neutral balanced) crank and requires a flexplate/flywheel "without" a counter-weight.

You need to find out specifically what your rebuild stroker crank requires (front and rear) from the crank manufacturer.

WD

 

OK I think I got it. Basically I need to take apart my rotating assembly right now before I have a big problem. My Crank when purchased is an Externally Balanced crank. Notes on the crank stated must use a 400 Flex plate and 400 damper. Now as far as the 400 damper. I should be able to use my stock Harmonic Balancer if I take the Balancer and the rest of the rotating assembly to be balanced right? For the stock LT1's I believe the cranks stock are allready externally balanced. Based on this information that you guys have given me. Im going to pull everything out and get it Balanced properly. I do not wanna have any issues with this rebuild. I have waited to long to get all these parts togather to mess this stroker rebuild up. I wanna thank you guys deeply for helping my out on this issue. And Im glad I did more research before I actually finished the motor with out balancing it
Thank you
Chris

 

That is true for the "rear" of the stock LT cranks and require a flexplate/flywheel with the counter-weight.

Although, the front of all stock LTs are "neutral" and use a dampner (not a balancer).

Again, the front and rear of the cranks are two different situations.

WD

 

If I were you, I would take it to a balancer and have them tell you what it needs to get it right. Balancing is not the most expensive thing to get done, but if it's wrong it will definitely bite you in the *** in the long run. I paid $175 to get ALL of my stuff balanced internally. (crank, rods, pistons, bearings, etc.) Cheap insurance in my opinion. Spend the money now or take it in the shorts later.

B