timing skips

[gregorious]

i have a mercruiser 485 and have changed the points to electronic about two years ago and timed it and ran well at home but put it in the water and it skipped on the way out at 3/4 throttle, got back in and brought it home lifted the distributor and moved the gear on spline put it back in and worked fine until this year when i put it in reverse to spin the weeds off of the prop to power up to leave the channel. It spit and sputtered and died,did get it started and took off but didnot want to start to come back in, finally started and when at shore opened dist.cap and noticed it was no longer timed again. Checked the rollpin on the distributor gear for being sheared and is fine. Does anyone have any ideas why it skips timing ? a friend thinks cam shaft bearings or the shaft is worn letting it move or timing chain but the shop i deal with keeps telling me there are not any parts available for this engine !!

 

[Fun Times]

You might want to try getting ahold of an inspection camera to get a good look at the CAM gear to ensure it appears okay. Also if possible, try measuring the distributor gear from the old one to the new one to ensure they are the same size, etc..

Years ago there used to be issues with mismatched Distributor to CAM gear material causing the distributor gear grind down to nothing left.
Also see if the info within the following link will help at all, http://performancedistributors.com/professional-tips/

 

[gregorious]

Thank you Fun Times for the input and will try to find something to inspect better. I did put my finger against it and it felt like there was some grit. Will check out your link and hope to get back down to the boat and back together later in the week and try it again