I've got my Fiat, FNM, CMD Engine running beautifully now.
I have a Twin-Disc techno drive TMC 60 behind it.
In neutral it makes a clanging noise, in forward it stops but in reverse it gets noisy again,
Anyone have a clue what it could be?
Could be a torsional incompatibility between the engine and gear box as a result of a damaged or worn out spring plate/ damper mounted on the flywheel. In neutral the damper may be clattering, or if the damper is too stiff it could cause gear tooth clatter in the transmission. When you put it in forward the system loads up from propeller load and the noise goes away. Reverse may be noisy because the power travels across a different set of gears and idlers.
Does the noise diminish if you raise the RPM a few hundred?