I've rewatched some of FMP's videos on using this calculator and I think I understand one aspect of it better.. how adding and subtracting base gaskets affects the PBT field. I was getting confused because some of his videos use another calculator that seems to use squish value instead of PBT, and when he uses this calculator, he doesn't directly say the gaskets should be added to piston field if not decking the top of cylinder, just put two and two together when i saw some graphic he put up at the end of a video that mentioned removing the gasket thickness from the top which to me would translate to him not changing that field.
Exhaust and transfer values are entered as is from most recent careful physical measurements..
PBT is entered as is to top of cylinder, if you add a base gasket, you subtract that gasket thickness from exhaust and transfer port value, but you add it to the pbt value so for example my pbt is -0.71 with no gasket, but add a 0.25mm gasket and it becomes -0.96, because piston is now that much further below top. He does not change the PBT value in the calculator in his videos because he shaves that gasket thickness off the top of the head to keep the squish exactly as before and counteracts the addition of the base gasket on this value. Also, the head measurement does not play into this pbt field in this calculator. It isn't squish, but just the piston below deck and any base gaskets that change that distance... I think?
So I believe this is my correct calculations for if I were to make adjustments with the current 57mm crankshaft (which I am not doing) to hit 176Ex/120Tr/28Bd...
Measurements
Exhaust - Orig: 36.28mm (no base),
Adjusted: 34.6mm (0.5mm base gasket + Grinding 1.18mm up towards top)
Transfer - Orig: 47.41mm (no base),
Adjusted: 46.91mm (0.5mm base gasket added)
PBT - Orig: -0.71 (no base),
Adjusted: -1.21 (0.5mm base gasket added)
Timings:
Exhaust - Orig: 167,
Adjusted: 176
Transfer - Orig: 114,
Adjusted: 120
Blowdown - Orig: 27,
Adjusted: 28
Squish - Orig: 1.85mm (0.71 PBT + 1.14 Head),
Adjusted: 2.35 (0.71 PBT + 1.14 Head + 0.5 base gasket)
From the instructions.. squish should be 1.1, which would mean without base or head gasket, I would need to take 0.75mm off the top of the cylinder to get from 1.85 to 1.1.. and for the adjusted setup with 0.5mm base gasket and no head gasket, I would need to remove 1.25mm off the top of the cylinder to get back to correct squish as instructed.
Does this sound correct?