Timing Mercruiser 140

trobin0406

Seaman Apprentice
Joined
May 31, 2016
Messages
33
I know everyone... not another timing post... but i have read a ton of them the past few days and am still struggling. I have an 85 sea ray seville with the 140 in it. She ran great but couldn't hold an idle. I cleaned out the carb and added a water/fuel separator. Added new plugs since the old ones were MR44t. Now i am trying to check the timing and with it barely idling at 800rpm it was at 12ATDC.. is there a base timing mode i need to put the motor in before making changes to the timing? I know newer ones you have to put a jumper wire in but i have looked all over the area and did not see any wires. The only wire i see is the one going to the coil.

Is this motor old enough where i just need to make changes to the distributer without a jumper wire?

Thanks again everyone!!
 

Scott06

Vice Admiral
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Apr 20, 2014
Messages
5,542
I don't think there is a base timing mode, not sure factory setting but I think you should be 1-2 deg btdc so timing is way off. You make agave points and condenser that need attention in this rig.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
What ignition system do you have? (An engine serial number and year would also help)...

If it's points, then no 'base mode', just timie the engine to 6 deg BTDC at 650-700rpm.
If it's DDIS, also has no 'base mode', but is timed at 8deg BTDC at 650-700rpm.
If it's EST, then yes, there is a base mode, timed at 1 deg at 700rpm.

Chris.........
 

trobin0406

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May 31, 2016
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It is points. They looked alright but i can change them if you think they go bad quickly. It runs great just doesn't idle.

This morning i attempted to time it but it just kept changing. I would turn distributer until it was about 6BTDC and it sounded better but the RPM would rise. So i would lock the distributer down and adjust back the idle screw to lower the RPM. Then i would recheck timing and it would be off again. I also noticed when timing, the mark would shimmy a little bit and not solidly stay at a degree. I have attempted it a few times and each time i would shut it off for a min and then turn it back on and timing would be off again.
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,684
The timing will change with idle/engine speed.
Don't lock the distributor down until you have both at the correct setting.
The idle speed of 650-700 is in gear, in the water I believe.

It could be a carb problem if it won't idle.
 

trobin0406

Seaman Apprentice
Joined
May 31, 2016
Messages
33
I ordered a carb kit the other day and will install once it gets here. I am starting to think its more of a carb issue because i will adjust timing, then lower RPM, then adjust timing, then lower RPM... I unscrewed the idle screw so far out it wasnt even contacting anything and if i remember correctly the book says screw it in until it just makes contact and then 2 full turns. So its way off.. But its odd the boat kept running fine while the idle screw wasnt making contact and i checked the idle mixture screw and it was about 1 3/4 out. Just seems odd to me. Maybe otheres have had a similar situation.

I also noticed the choke cam ( i think thats what its called) doesnt really do anything and my choke seems to not work. During timing thought i let the motor warm up for 10 mins and adjusted the choke to stay open so it didnt effect my timing.
 

trobin0406

Seaman Apprentice
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May 31, 2016
Messages
33
Well i wanted to provide an update on this. After an hour of playing with it i believe its good.I will probably buy a dwell meter to be sure that is correct and recheck timing on the water since I still need to make final adjustments since it needs to be in gear.

Thank you everyone for your help!!!
 

Starcraft5834

Lieutenant Commander
Joined
Jun 2, 2013
Messages
1,677
It is points. They looked alright but i can change them if you think they go bad quickly. It runs great just doesn't idle.

This morning i attempted to time it but it just kept changing. I would turn distributer until it was about 6BTDC and it sounded better but the RPM would rise. So i would lock the distributer down and adjust back the idle screw to lower the RPM. Then i would recheck timing and it would be off again. I also noticed when timing, the mark would shimmy a little bit and not solidly stay at a degree. I have attempted it a few times and each time i would shut it off for a min and then turn it back on and timing would be off again.



if this helps, Ive got a 1987 3.0 GM 181, just put a Pertronix Electronic Ignition in it with Flame Thrower Coil 40K volt... no more resistor wire.. timed to 6 BTDC, idle is 700-800 rpm, purrs like a kitten.... pretty sure 6 is the # you want on that engine... I contacted Pertronix about timing, the feedback I got from them as well as others here was the same, timing is not changed, "a spark is a spark", set to original spec,, i believe 6 is the # for u also.. I have noted faster start up with electronic ignition, electronic ignition with 40K flame thrower sparks hotter... it's been wired when running to drop voltage so not to burn out the plugs..
 
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