bcarp

I am in the process of installing a new crank pulley and I am going to go ahead and pin it but it has a keyway cut. Do I drill on the opposite side? or do I drill the crank where the pin will slip in the keyway?
Thanks Bob

itzza427

Not sure about the pin,,but I'd leave the key way alone as that is critical to proper alignment of the pulley!!

lucky131969

Really?, can you explain how the crank is keyed on a stock LS1/LS6 ?

bcarp

My crank does not have a keyway, if it did I wouldnt worry about pinning it

lucky131969

No, do not use the keyway on the balancer for the pinning. You need a pinning jig, using a non-keyed part of the balancer.

bcarp

Ok thanks I have the pinning jig just didnt know if I should use they keyway or not.

MikeV

You should pin it 180 deg from the keyway. The keyway will induce a little imbalance due to the fact that there is no key in place.

Mike V

lucky131969

So how does this effect all those guys who have installed an aftermarket balancer with a keyway, and do not have a pinned crank?

Independent1

bcarp

I am going with this plan.
I bought it from Englandgreen maybe he will chime in

MikeV

Its just a little inaccuracy. But if you are going to pin, you should choose a place that will help the problem thats all.

When you balance precision equipment, the best way is with everything in its working location as even wind can change the balance depending on the type of equipment. I.E. fans.

Mike V

lucky131969

Since the pin is close to the axis of rotation (and considering the countless number of balancers with a keyway that have been installed and pinned without issue), it is not a big deal; however, I don't follow your logic. Whether you pin the balancer 90 degrees from the keyway, or 180 degrees out, you are pressing a pin in the hole you just drilled. So you are removing mass from the crank and balancer, and replacing the mass with the pin you pressed in. Now, I recognize that the density of the balancer, crank, and hardened pin are all different, but again, you are still replacing what you removed with the drill bit. That being said, if you were just drilling a hole, and not pinning for some reason, then I agree 180 degrees from the keyway would make sense.

BLOWNBLUEZ06

I actually took a carbide bit and radiused my keyway, aligned it with my existing pin location and tapped the pin in. It fit quite nicely.
180° out will be fine too.

bcarp

Tell me more

lucky131969

So you put a round peg in a square hole...purposely....

Y2Kvert4me

To eliminate some confusion here....there's two ways to pin a crank.


One way (the method being described here) is used with stock balancers..it involves installing/torquing the pulley first, and using a jig, drilling a hole in from the end of the crank. The hole (and pin) becomes centered at the seam between crank OD, and pulley bore ID. Once hole drilled, pin is tapped in.
The net result looks like this:




The other method (used with keyed pulleys), is called vertical pinning...The ATI pin kit uses this method.
it uses a dowel pin (or 2) of the same dia as the keyway is wide (ie, 3/16"). A hole is drilled into the side (or top) of the crank snout (not the end), a short dowel pin(s) is pressed in, sticking out of the side of the crank the same depth as the keyway of the pulleyi. And then the pulley is installed, aligning keyway up with the pin(s), and drawing it on.

You use a fixture that looks like this to insure the pins are perfectly centered and straight, so they line up with the pulley keyway:

MikeV

You are going to have voids from the orginial material no mater what you do, so it may be lighter if the material weighs the same. We are talking fly **** here... so 180 out is just best practice. Its not like its going to cause a problem.

Mike V

lucky131969

bcarp

Apparently you have been down this road, what would you do? I am not too thrilled about drilling my brand new balancer.

lucky131969

If you never plan on any power adders, then leave it alone. If you plan on high HP or FI in the future, then might as well do it while your in there.