Sync & Link - yikes, glad I did it.

[Moody Blue]

Finally got around to performing a sync & link on my 1971 Merc 800. Bought it last season but only ran it once briefly in early fall before winterizing it just to see if it was a runner. It ran but not a good as I would like and the idle was unstable.

Followed the procedure posted by Clams Casino (thank you for such an easy to understand/follow procedure) and found the following timing setup.

Throttle pickup timing was set to about 16 degrees BTDC (spec is 3-4) and the max spark advance at 28 degrees BTDC (spec is 21). Also found the secondary throttle pickup didn't engage till well after max spark advance. I did verify (dial gauge) the TDC timing mark to be sure these numbers were legitimate.

No idea how this would have translated into performance issues since I've never had it on the water. Got it set up right now and tomorrow its time to fire it up and see the results.

 

[daveswaves]

Re: Sync & Link - yikes, glad I did it.

Let us know how it runs. It would have been difficult to start and have too fast an idle with the settings as you found them. Mercs of this vintage dont tune the same as Johnsons and its very likely that somebody tried to make it run better by "adjusting" the three timing/idle/advance screws. No doubt they would have adjusted the carbs too. If you followed Clams procedure you should be good to go. If you find it falls flat on its face when you accelerate then back out the carb screws 1/4 turn each and try again. Repeat until you get rid of the stumble.

 

[Moody Blue]

Re: Sync & Link - yikes, glad I did it.

Well got the motor running fairly well I think. Only running on muffs for now till the boat is done.

Started up quite easily. Had trouble getting a steady idle without feathering the throttle. Kept wanting to stall. After fiddling with the idle screws I did get the motor to idle down to between 750-800 rpm which I think is pretty good. It will do for now till I can get it out on the lake and do a full test.

Should I try for a lower idle speed or be satisfied with what Ive got?

 

[macbee]

Re: Sync & Link - yikes, glad I did it.

Quote: Followed the procedure posted by Clams Casino (thank you for such an easy to understand/follow procedure) and found the following timing setup.

Can anyone please tell where I can find this "Clams Casino" information.
I have hunted through the Engine FAQ's without success.
Much obliged
Bill

 

[daveswaves]

Re: Sync & Link - yikes, glad I did it.

Well got the motor running fairly well I think. Only running on muffs for now till the boat is done.

Started up quite easily. Had trouble getting a steady idle without feathering the throttle. Kept wanting to stall. After fiddling with the idle screws I did get the motor to idle down to between 750-800 rpm which I think is pretty good. It will do for now till I can get it out on the lake and do a full test.

Should I try for a lower idle speed or be satisfied with what Ive got?

750 to 800 is a good start and indicates the reed system is ok, if the reeds are bent or not closing you would never get it that low. When you do get it on the lake if the engine stalls when you put it in gear or when you load it back the screws on the carb out 1/4 turn on all 3 and try again. Repeat until the engine does not fall flat when you load it up. Ideal set up is the engine idling in gear at 500 rpm and in neutral at 800. As long as its under 1000 then the gear box will be happy. The lower the better as long as it stays running when you shift back and forth. You need manueverability and reliability when docking your boat

 

[Moody Blue]

Re: Sync & Link - yikes, glad I did it.

Macbee, here you go.

http://forums.iboats.com/showthread.php?t=168855

 

[Chris1956]

Re: Sync & Link - yikes, glad I did it.

Moody, if you hit the primary throttle pickup at 3-4* BTDC, the secondary throttle pickup is automatically adjusted. I am unsure what you meant by Secondary throttle pickup starts past max advance. The carbs should be about 2/3 - 3/4 open at max spark advance.

For primary pickup, you need to loosen the bolts on the brass collar on the dissy, and turn the plate to just touch the carbs, at 3-4*BTDC, then tighten. The idle stop screw really sets minimum spark advance(usually several * ADTC) however, you do not care what this is, you only want the minimum idle speed.

 

[macbee]

Re: Sync & Link - yikes, glad I did it.

Many thanks Moody for passing on the Clamscanino info. Very useful stuff.