Quick TDC Question

[kdog_x]

OK, I'm reinstalling my balancer, my distrib is out so I won't be using that as a reference. So I have to find TDC manually from the #1 spark plug hole.

I cranked till I knew it was on the compression stroke. Then I put a screwdriver in there to try to find where the piston hits the highest point. My problem is that it hits the top and then stays there for about 10-15 degrees of a rotation. Where should I set it so I can reinstall the balancer correctly? Right when the piston first hits the top, right before it goes back down, or somewhere in the middle?

BTW the engine is complete and the heads and valve covers are on. So I can;t see the piston

thanks

 

[TRWXXA]

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.

 

[351LX]

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.

 

[kdog_x]

Yeah, I ended up pulling the balancer off and I was pretty close to TDC. I just made sure the keyway on the crankshaft was facing straight up, then I pulled the dizzy and reinstalled it so that it was pointing to the front right intake manifold bolt (#1 cyl).

I'm really confused though. The mark on the balancer does not line up with the timing pointer (not even close). When the keyway is pointing straight up, and I install the balancer, the notch in the balancer (0 degree mark, right?) is about 170 degrees clockwise (making it face toward the ground).

I thought that the balancer must have spun, but I just went to autozone and compared it to a new one. The keyway/notch are in the same relative positions on the old and new one.

I have no idea why that is, can anyone enlighten me?

thanks