Are Cranks Interchangeable Between Years?
- Thread starter LBZ
- Start date
It my understanding that you've got to use the same year balancer and flexplate/flywheel with same year crank.
A flexplate that can be bolted to ANY crank??? Unless it's got movable weight, I don't think I'd trust that statement...
AKAIK, the flexplate's on these trucks are specific and need to have a certain weight offset per engine designation. I've got a billet piece from SoCal for an LBZ and it's different from the LB7 and early LLY version, but the same as the late LLY and LMM ones.
SoCal does make a "neutrally balanced" flexplate for guys that are internally balancing the rotating assembly, FYI...
Also AKAIK, the cranks are interchangeable between all the engines up to the LML I don't think an LB7 crank can be used in an LML but I'm not sure...the LB7 crank is said to be stronger than the others, maybe due to the added mass or just because of the way it carries the added weight but it is heavier by I wanna say 14lbs or so as compared to an LBZ crank...
The balancer for the LB7 is something like 4.5lbs heavier than say an LBZ balancer too, so again I'm pretty sure they're specific to particular engines. I'm pretty sure the balancer and crankshaft's overall size/dimensions are the pretty much all the same tho. You'll definitely have to have your rotating assembly balanced to utilize the LB7 crank in an LBZ but you can do it.
AKAIK, the flexplate's on these trucks are specific and need to have a certain weight offset per engine designation. I've got a billet piece from SoCal for an LBZ and it's different from the LB7 and early LLY version, but the same as the late LLY and LMM ones.
SoCal does make a "neutrally balanced" flexplate for guys that are internally balancing the rotating assembly, FYI...
Also AKAIK, the cranks are interchangeable between all the engines up to the LML I don't think an LB7 crank can be used in an LML but I'm not sure...the LB7 crank is said to be stronger than the others, maybe due to the added mass or just because of the way it carries the added weight but it is heavier by I wanna say 14lbs or so as compared to an LBZ crank...
The balancer for the LB7 is something like 4.5lbs heavier than say an LBZ balancer too, so again I'm pretty sure they're specific to particular engines. I'm pretty sure the balancer and crankshaft's overall size/dimensions are the pretty much all the same tho. You'll definitely have to have your rotating assembly balanced to utilize the LB7 crank in an LBZ but you can do it.
That's what Dustin at ATP told me when I asked why the LB7's were thought to be stronger... But the funny thing to me is, the shaft size is the same...so technically all the weight is in the counterweights?
At any rate, I'm just regurgitating information I haven't weighed them myself so I don't know for certain
What I meant is the same style of SFI can be bolted onto any crank but I believe it has to be ordered for that particular model. Same for the balancer. As far as being heavier I'd believe a pound or two on the crank but definitely not 14.
Like I said my concern is if the piston will clear the counterweight. I remember we had an issue with the first build in Abby that the pistons were lbz and the crank was lb7 and the skirts hit the counterweight. We had to shave 55 thou off the bottom of the piston.
When balancers and flywheels get ordered it will be for that particular crank.
Like I said my concern is if the piston will clear the counterweight. I remember we had an issue with the first build in Abby that the pistons were lbz and the crank was lb7 and the skirts hit the counterweight. We had to shave 55 thou off the bottom of the piston.
When balancers and flywheels get ordered it will be for that particular crank.
Aftermarket rods and pistons are not model specific so I'd say what your worried about won't be a problem.
That's a good point.
I'm going to try a new LB7 crank out and hopefully it doesn't break. An AF cam will also be installed.
http://www.trademotion.com/parts/20...number=97225901&vehicleid=96599&siteid=214858
If that works...
GM parts direct has them at $841.
01-10 will physically go in an any year block. Balancer and flywheel have to be correct for that crank. Lb7 and LLY share the same balancer and flywheel, LBZ and LMM share the same balancer and flywheel. Than of course the reluctor wheel had to be correct.
Any reason for wanting to put an LB7 in your LBZ? After breaking a brand new lb7 crank with less than 5,000 miles leaves me to believe there is no benefit to the swap.
Any reason for wanting to put an LB7 in your LBZ? After breaking a brand new lb7 crank with less than 5,000 miles leaves me to believe there is no benefit to the swap.
Well actually for that reason alone was my thinking. I had heard of fewer failures with the LB7 and LLY cranks. I figured if I was going to buy new I would be better off buying an LB7.
Yo can't just base your one experience and say an lb7 crank is a bad idea... There are way too many variables to account for. Whos to say that the exact same thing wouldn't have happened to you with an lbz crank.
I will tell you one thing for sure, I will never go through the trouble to put an lb7 crank in my engine again because it proved to me that it does not make any difference. My LMM stock crank took a ton of abuse and didn't break and this brand new almost $1,000 lb7 crank that had an ATI balancer and was balanced made it 5,000 miles and broke like all the rest of them do. I'm not saying it is a bad idea, I'm just stating that I will not go through the trouble to do it. They are hit and miss on breaking and I think it doesn't matter what year you put in it