HELP! timing 3.7 merc with points

[vicsponjr]

I need some help. I have a 3.7 merc i/o with points and have been having trouble running at idle. After about ten minutes it starts bogging down and wants to stall. Runs great at mid-3/4 throttle. I put a timing light on it and it was at 4 degrees. Book says 8. I turned the distributer to bring it up to 8 and the idle went up. So I lowered the idle and the timing back. Advanced the idle again and the idle increased. lowered the idle and it started running like crap. Checked the points, they were at 17, move them to 22. I don't have a tach so I don't know exactly how fast the engine is idling. The boat is in the driveway so I'm not getting a real feel for anything. Could it be the carb? Please help. This is really frustrating.

 

[Don S]

Re: HELP! timing 3.7 merc with points

You need to set the point dwell first, the dwell will affect the timing.<br />After getting the dwell set, then set the timing to specs at the proper rpm.<br />The proper specs depends on if you have a Prestolite or Delco distributor.

 

[vicsponjr]

Re: HELP! timing 3.7 merc with points

Don,<br />How can I tell the difference?

 

[vicsponjr]

Re: HELP! timing 3.7 merc with points

Does anyone have a picture of the 2 distributors?

 

[Don S]

Re: HELP! timing 3.7 merc with points

Delco Distributor <br />

<br /><br /><br />Prestolite Distributor<br />

 

[vicsponjr]

Re: HELP! timing 3.7 merc with points

Don, when you say set the point dwell, do you mean gap them? I set the point gap to .022 as per the manual. I don't have a dwell meter, or even remember how to use one. Haven't delt with points since my first car in 82.