Quick TDC Question

Technically, true TDC is exactly mid way between the point in the crank rotation when the piston first comes to a stop, and when it first starts down again.

I'm not sure if this is enough to help you find TDC accurately enough to replace the balancer. I think you have to get it within a degree or two.

There should be a keyway on your crank and balancer so that you can only put the balancer on in one position.One method that I have used to find TDC is to take an old sparkplug and remove the porcelain part.Put a bolt that sticks out 1-2" through the plug and secure it in place by either welding it or by tapping the inside of the old plug with the same thread as the bolt.Smooth the end of the bolt to remove sharp edges and thread it into the plug hole while the piston is down the cylinder.Rotate the engine by hand in one direction until it lightly contacts the stop and mark the balancer.Rotate it the other way and do the same.TDC will be exactly in the middle of the two marks.Remember TDC occurs on both the compression and exhaust stroke so you need to determine TDC on the compression stroke to line up the distributor.Also it is a good idea to loosen the rocker arms on that cylinder to eliminate any chance of the valves hitting the bolt.