1967 Merc 650 Thunderbolt - Intial Pick up Timing Issue

[79SylvanRod]

I am at a loss. I cannot get the initial spark timing down on my 1967 650SS Thunderbolt. The red line on the timing tape marks the timing pick up location per the FSM. TDC was found using the piston stop method and later confirmed with a dial indicator. TDC on the flywheel lines up perfectly with the distributor gear marks.

Photos:
- Timing tape on cowl support: The red line is covering the black pickup line location. Disregard orange lines.

- Side of distributor: When both dotted red lines touch, that is where Cyl #1 sparks when the TDC flywheel mark lines up with the red line on the timing tape. I would have to trim 5/16" off the plastic stop on the idle speed screw to allow the distributor to rotate further clockwise for both dotted lines to touch. I know this isn't normal. This photo was taken after I bolted the timing screw plate back on.

- Throttle pick up plate: I have maxed out the throttle plate and cannot reach the carb cluster if I use the red line. It's almost like I am off a tooth or two on the timing and I know I am good. The eight bolts on the top of the flywheel looks like they have never been removed.

Any recommendations? The flywheel would have to be roughly 26 degrees BTDC for the cyl 1 to spark at the original idle screw setting (pre-distributor bearing and trigger replacement).

What has been fixed:
- distributor bearing
- trigger with NOS part
- carbs cleaned and synced together
- custom engine wiring harness
- lower unit serviced
- new spark plugs
- black fuel lines from gas tank to fuel pumps and carbs