Differences between LB7 and LLY bottom end?

[Bluemax]

Just because the Cranks are different doenst mean that the balance is. Lets not get our panties in a knot yet. Im more than willing to bet its the same. The LBZ would need more weight due to the beefier rods and the (most likley) lighter pistons .

My panties aren't in a bunch yet. Just want to make sure all the parts I bought are going to work together and make sure that I use the strongest parts if there is a stronger one. I only have the money to do it once. And if it goes south I'm screwed, and I don't want to go down that road. I don't have a choice because it's my only dependable means of transportation, and sadly enough its my play toy too.

 

[Ben46a]

Nobodies panties are in a knot!:rofl: If it looks like I was argueing I apoligize!

Nono, It just looked like everybody else was all of a sudden thinking that the parts arent interchangable because the crank is different. I think you and me are in the same train of thought here. Sure the weights arent in the same place, but LB7 and LLY's call for the same manual trans flywheel , and dampner, which would indicate similar balance carachteristics. With this information, knowing that the rods and pistons are also the same, would indicate that the cranks, although different, are interchangable.

 

[LarryJewell]

I only have the money to do it once. And if it goes south I'm screwed, and I don't want to go down that road. I don't have a choice because it's my only dependable means of transportation, and sadly enough its my play toy too.

Same for me as well :baby:

 

[Bluemax]

Nono, It just looked like everybody else was all of a sudden thinking that the parts arent interchangable because the crank is different. I think you and me are in the same train of thought here. Sure the weights arent in the same place, but LB7 and LLY's call for the same manual trans flywheel , and dampner, which would indicate similar balance carachteristics. With this information, knowing that the rods and pistons are also the same, would indicate that the cranks, although different, are interchangable.

I know the cranks are interchangeable, however I'm looking for what is going to be the better way to go. And seeing as I have spent a considerable amount cash on this already, I'm wanting to make sure I am not buying stuff that won't work. What you said about the flywheel and balancer gives me some hope. I've already bought a solid flexplate and a fluidamper for an LB7, but if the balance is different between them that makes a big problem for me, close is not going to work on this one. See where I'm going with this.

 

[big_jon00]

From what I have seen the counter wieghts on the LB7 are at the ends of the crank and the LLY has middle counter weights.
Jon

 

[Bluemax]

I would be more than happy to take a pick of my 02 crank in the block to show the weights. I have to go to the dealer to pick rings tomorrow. If I remember I will check the balancer part # for a 05 LLY vs. a 02 LB7

I realize I didn't ask before you went, but did you happen to take any pictures or check the part no. on the balancers?

 

[Ben46a]

They are the same.

 

[JOHNBOY]

Sorry!
Yes they are the same part # according to my dealer.

 

[Trippin]

As far as balancing goes the LB7 and LLY up to and including 2005 are the same. Same counter weight in the balancer and flywheel, same spec used at GM. This has been verified from GM prints and in the field while doing my research for building the stroker kits.

As you have already discovered GM uses the same part # for replacement cranks for both.

The 2006 LLY/LBZ is a different animal. The diameter of the crankshaft counter weights was reduced to accomodate the new piston that had more mass around the wrist pin boss which was updated to include a bronze bushing.

This was a double whammy. A 50 gram heavier piston and pin combo along with smaller counter weights made it neccessary to use a heavier counter weight in the flywheel and the damper to get the whole mess to balance properly.

Hope this helps,

Guy