1975 mercury 850, Cant find timing marks,,

jeepthangs

Recruit
Joined
Jul 8, 2010
Messages
2
Thanks for reading this post. I have been told too many things from too many people around here and really need an answer. I have read many posts and can relate to a lot of them. My flywheel only has the three small dots in a vertical line. No timing decal. Some people say it is the wrong flywheel. Others say the timing marks should be on the cowl. I set the #1 cyl to TDC and set the small arrow on the dist with the three small marks. Engine starts great and runs great, but will not run in the water. I dont how to adj. the high side without marks. Could someone Please tell me where the marks are supposed to be on the motor. Then I could do the link and sync. Thanks for your help in advance.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,910
Re: 1975 mercury 850, Cant find timing marks,,

OK, It sounds like the decal on the flywheel is missing. I think they are NLA, but you should check at crowleymarine.com and dougrussell.com and confirm. If you cannot find one, you need to make one. Accurately measure the circumference of the flywheel and divide it by 360*. Now make the decal with TDC, 5* BTDC, and 21* BTDC. Those should be all you will need to set idle and max spark advance.

Some of those older motors had timing marks on the upper cowling support. The newer models has a timing pointer instead.
 

jeepthangs

Recruit
Joined
Jul 8, 2010
Messages
2
Re: 1975 mercury 850, Cant find timing marks,,

Thanks so much, I really really appreciate your advice.
 
Top