Regarding using a Harley engine, they are not a direct replacement for the S&S X-wedge. The engine mounting bolts are larger and are spread wider on the S&S motor. Of course mounting plates could be fabricated to adapt the Harley motor and align it with the Morgan drive components.
Using other S&S motors except X-wedges would run into the same problem as they are made to fit Harley mounts. Also, a number of them are for older bikes and are not emissions compliant, but the newer motors might pass emissions.
I always thought the S&S Knucklehead motor would look good on a Morgan but it is not compliant.
Correct, the engine mounting is different. The S&S Wedge motor is designed with vertical mounting in four places, and more typically used in a solid bolt to the frame mounting. They are also a "standalone" motor. That means, unlike the Harley, they do not have any mounting for a transmission as used in a bike application. They use the "old EVO" style separate motor/trans with the side primary doing the alignment and the both units are frame mounted after the primary case has been bolted to both motor/trans for alignment.
Also the S&S Wedge uses Harley's pre-'06 primary side mounting, four bolts versus five bolts. So the Morgan motor to trans adapter will NOT bolt up to '07/later Harley "B" motors. The "B" motor starting in '99 was fully counterbalance with a front and rear counterbalance shaft driven via chain off the cam side of the crank. This allowed the "B" motor to be solid mounted to the bike main frame, sans the "A" non-counterbalanced motor's rubber mounting system for all touring bikes. The "B" motor is ONLY used in Softail frames.
So the motor in the ACE is an '06/pre "B" motor. Harley does offer an '06/pre 120R version of the "B" motor, which is what we've been looking at in all the posted pictures. This motor lists in the $8k range with street pricing in the $6.5k range.
With the "B" motor you can very easily run the S&S Super series carb so you do away with the EFI and whatever troubles that may bring. Thunderheart offers a standalone ignition system that hooks directly up the crank sensor next the alternator plug in the front of the motor, or left rear side of the S&S Wedge. It can be programmed via several preset profiles, or tuned if needed. The Thunderheart runs in the $300 range and then the carb is probably in the $500 range for their carb kit with AC and manifold.
Someone here has converted their M3W to a carb, can't remember off the top of my head though. I remember that it ran well also.
With a carb and standalone ignition, most of the irritating ECM and tune issues go away.
I've ridden several "B" powered Harleys. Most at a stoplight don't vibrate at all. You know they're running because of the loud exhaust.
They are VERY smooth.
In the realm of the of the 120R motors, they are very highly rated by CVO guys that have swapped out their CVO FL series touring bike 110" "A" motors to the 120R "A" motors. They put out to the rear wheel well over 120hp and equal to that or more in torque.
I think if someone had a S&S failure and was handy with the welder and plate cutting, the 120R would be a great motor for the M3W. But alas, that would take away from the "stock" nature of the M3W. Kind of like putting a SBC in a Mustang, blasphemy to some. Of course exhaust would be an issue, but not out of the question. Especially with several of the M3W members making, or having made, complete new exhaust system for the S&S motors.
Sorry for rambling again guys...