distributor rotor not turning 525sc
 

525sc motors. Roughly 100 hours
Running 4000 rpm last weekend port motor shut down would not start up again. Trailer ed it home.
Tonight turned it over and saw all the rockers moving. Pulled distributor and roll pin is still in tact.
Turned it over while looking down the distributor hole and could not see the cam gear moving.

What am I looking at here? broken cam?

thanks in advance

Sounds like it,

Crane had a bad large batch of hyd roller cams years back that did this, but I have not heard of a flat tappet cam (525SC had hyd fat tappets) doing this, but I guess anything is possible.

perfect opurtunity to upgrade the cam and valvetrain !

A broken cam is the only thing that would do what you describe. Never heard of it happening on a 525SC though.

SB - i have crane roller cams on these engines

If the cam is rolling and cycling rockers but the cam gear isn't moving....only one thing that can be...bad cam....its possible I guess if the cam gear is pressed on that it could have came loose and is slipping...however regardless the cam needs to come out IMO

looks like SB nailed it...........btw ^^^^^^the gear is machined into the core

update
 

Cam was broken in Starboard engine. - sent them down to Larrys Engine and Marine in Tucson, AZ. did Both Engines and completely.