TDC actual vs. mark on fan Options

[jmargush]

Has anyone experienced the mark on the fan being off from where actual TDC is ?

Last time I had the engine out I put a dowel in cylinder #1 and found TDC and the factory mark was approx. 3/8" tot he left of where I feel TDC on #1 was.


I am going to recheck it and see if I made an error the last time I did it.

[jmargush]

I just checked it with a dowel again.

What I think I am seeing is a bit of dwell at the top of the stroke. Dowel stops moving a bit before the factory mark on the fan.

Once it moves past the factory mark the piston starts to travel downward again.

Does this sound logical/possible?

[GregAmy]

I just checked it with a dowel again.

You can't calculate TDC with a dowel; to do it correctly you need a dial gauge and a cam degree wheel.

If you have a hard piston stop (another tool used for degreeing in cams) then you can rotate the engine until the piston taps the stop, mark the pulley (or read the degree wheel) then rotate the engine the other way until it taps the stop and mark the pulley (or read the degree wheel). The halfway point between those two marks is TDC.

https://www.summitracing.com/parts/sum-900189

GA