[Mister L]

I ended up selling my auto Mach to a buddy after putting about 1 or 2k miles on it. I went with Sean Highland’s recommendation on using auto cars original (cast crank) harmonic balancer mated to the 8-bolt forged crank. Car has a slight vibration in 1800-2000 rpm range while parked or doing 60mph (18-2000 rpm) down the road. Pulled driveshaft and tested on driveline machine for balance/runout and all checked good. Changed clocking of driveshaft to rear pinion-no change/still has slight vibration. When I changed torque converters, the one replacing original is larger in diameter and is balanced out of the trans minus fluid. I really think the vibration issue may be cured by replacing the neutral balanced flex plate with one like original (not sure of original flexplate balance properties or one of better quality) OR putting the forged crank/ 8 bolt harmonic balancer on the 8 bolt crank. It shifts fine but I wish it were smoother. No misfires, no codes, runs awesome and is not intended for race but just a daily driver. That’s the only issue I’ve had with an 8-bolt crank in auto Mach. An auto Mach balancer is heavier than the 8-bolt version. Perhaps there lies the problem with the larger diameter converter with the heavier harmonic balancer. I have a balancer off my manual car that I could put on it and test but I haven’t done it yet.

As for condition of engine that’s been sitting-if stored in a dry area I wouldn’t be too worried about it. My biggest fear would be hardened front or rear crank seals but those can be easily changed before installing in car