Thanks everyone! Some great food for thought. I will definitely be checking the pressure plate adjustment and go from there. Hopefully it's just the fingers. I do like the channel locks approach, and I have a giant pair. Guess it can't hurt to try, I will report any progress or lack thereof.
I guess it is all in what your expectations are. While I have not tried this method with the slip pliers, I feel very confident that I could squeeze the pliers by varying amounts to create 0.003 - 0.004 inches of deflection on the flange, -and maybe even more. If I can create that much difference in measurements, then your findings really won't be accurate IMO.
With regard to clutch chatter, I have read many times on social media sites about pressure plate finger adjustments being the cause of chatter however the majority of what you read on those sites is grossly incorrect IMHO. For the finger adjustments to be the issue, the pressure plate would likely slip too.
It has always been my experience that it is one (-or more) issues that causes 'chatter'. The root problem is
always related to alignment ...beginning with the centerline of the crankshaft, -then thru the transmission Main Drive Gear (input shaft), and on thru the Main Shaft of the transmission. The end of the crankshaft has a pilot bearing that must be concentric to the crankshaft main journals. This concentricity can be off due to improper crankshaft set-up in the grinder prior to grinding. This inconsistency is typically found more prevalent in crankshafts that were ground in machines that used chucks instead of centers. We can discuss this at a later time however just know that if the pilot bearing is not concentric to the crankshaft centerline, there will always be a disc centering (i.e.: 'chatter') issue.
So once the concentricity of the bearing has been established, the fit of the nose of the Main Drive Gear inside of the pilot bearing must be less than 0.001 (-e.g.: ½-thousandth per side) clearance. This is a tight slip fit without any detectible slop or lateral movement. If there is any excess clearance in this area, it allows the Main Drive Gear shaft to deflect out of the exact centerline of the crankshaft, and when the clutch disc is engaged to the flywheel surface, the disc will wobble or vibrate briefly out of the centerline until it can self-center. This non-concentric wobble is what you are feeling as 'clutch chatter'.
FWIW, there are other issues that can exacerbate the wobble such as a Pressure Plate that is not centered correctly onto the flywheel. This very common on flywheels that have been converted to a V8 style pressure plate. If there is not any alignment pins or pilot-shoulderd fasteners to index the pressure plate to the flywheel, then this can be the source of the 'chatter'. Also, it can be a flywheel housing that is not centered on the cylinder case block, -or it can be warped causing the transmission to not be in that exact centerline of the crankshaft, -and these can create a centerline issue. The other issue can be a worn Main Drive Gear bearing in the transmission case that is worn, ...again causing the Main Drive gear shaft to fall out of centerline alignment. If you are thinking that I am overthinking this, then take a moment to to think about all the places in these connections where these housings are piloted to one another either thru pilot pins or indexing counterbores before the fasteners are installed/tightened.
While on the topic of Flywheel Housings, it has been my experience that most flywheel housings are warped and need to be restored (-remachined). This is because this housing is what all of the movement of the vehicle is channeled thru, -and these constant forces is what causes this housing to flex or even crack over time. Contrary to what some will try to convince you, there is no reason for anyone to need to shim the flywheel housing to create perpendicularity to the crankshaft centerline. If so, something is incorrect. It can be the crankshaft is not parallel with the centerline of the engine case (-poor quality lineboring set-up), or the crankshaft machining was done incorrectly. As I stated above, it can also be the flywheel housing. Just understand that Ford did not 'indicate" the flywheel housing during assembly and then use shims to make corrections. The Flywheel Housing Shims sole purpose was to fill the void at the top 2 tabs that was created by the Flywheel Housing gasket thickness. It was never used to preload the housing to make it's mounting for the Clutch Housing perpendicular to the crankshaft centerline.
So the bottom line in all of this is measuring run-out with dial indicator and adjusting finger heights likely has little to do with correcting the clutch chatter. I'm thinking your issue is more likely to be in one of the areas I described above.
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