Timing question 77 FJ40 2F

[MarillaMarauder]

I have a digital timing gun that I can't set to BEFORE TDC. 0.0 is as low as it goes. My question is, when it is at 0.0, what should I be seeing in the flywheel window? The BB or the TDC line?
Right now I have the BB showing dead on but when it runs it knocks like crazy at higher RPM
I thought I could figure this out but it is driving me NUTS!! Thanks

 

[FJ40Jim]

At 0.0, adjust dissy so pointer is on the BB. Adjust timing light to 7, and the TDC line should appear at pointer.

 

[MarillaMarauder]

That is what I thought. The BB is lined up when gun is at 0. I just don't know what could be making a wicked knock when rpm's go up

 

[FJ40Jim]

With an advance timing light, it is easy to make a rough plot of the dissy advance curve.
Disconnect the vac advance hose.
Set the light to 5°.
Rev engine until BB comes back to pointer.
Note RPM.
Set light to 10°, rev up until BB comes back to pointer, note RPM....
Lather rinse repeat.... thanks