Engine Rebuild - 1962 650SS

Never seen that ( or never noticed ) , a revised tensioner fitted at some time ? Hydraulic ? 

Hello Alastair and Bob - I am thinking that someone has used  some Commando components in these cases.  I am fairly certain that my Commando camshaft chain tensioner has the same arrangement.  They don't have the second drive cog to turn the magneto or coil set-up behind the engine so the intermediate gear is much narrower.  The drive to the camshaft can be nearer to the inside face of the case. So if they have used a Commando camshaft and timing cover so that they can fit the points set-up driven by the camshaft I wonder how they would have driven the tacho? ....perhaps they used an electronic tacho .  Do you think I am getting close? I should check with Les Emery as you have previously told us that he supplied the cases and lots of other parts.

Sounds about right Howard , if they are commando cases that will bring other issues , perhaps Mercury cases? Which were apparently modified Commando ?

The number quoted suggests a pair of modified 650SS cases.  Mercury cases start with 129___ and Commando ones have a prefix of 20M.  A call to Norvil me thinks may be required......Cheers, Howard