Timing an engine

Rdock

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Joined
Dec 29, 2002
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9
Is there anywhere I can buy a manual that will teach me how to time an engine step by step. Also on where to buy the tools needed. I have a 2001 115 H.P.Merc. Or can you get me started in the right direction. I would really like to learn how to do this. Thankyou!
 

ob

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Aug 16, 2002
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Re: Timing an engine

Rdock, You can obtain a factory manual from several places or get a general one at the bottom of this page.Not sure whether the general service manual will have specifics on timing set-up.Here's one site for factory manuals.Click on outboard motors,Mercury and then on engine manuals in the upper right box.They run around $45.<br />www.marineengine.com
 

12Footer

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Mar 25, 2001
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8,217
Re: Timing an engine

Yes. The Clymer manuals usually have such information in the front pages...Things like reading engine condition by plug appearance, and basic "how-to's " on timing, testing, ect, and basic carb priciples yadayada.<br /><br />But this stuff is not easy to start with zero wrench time in cars,or other mechanic werk. I'm not saying it's impossable, just hard to start from scratch. Most of the tools you will need are standard, off-the-shelf stuff, available at the nearest auto parts,hardware, or building supply stores. Of course, other tools are only available from the engine maker,and are absurdly expensive (for the most part) for what they are.<br />Most boat owners who do thier own maintainence, started by just aquiring the tools as they needed them, and many opt to make thier own or have the tool made . this category includes such tools as prop bearing carrier wrench, made out of a pice of 2" galvanized water ppipe. Maybee not as sturdy or pretty as the factory tool,but gobs cheaper.<br /><br />But back to timing. Timing on most outboards is largely linkage movement, and seldom "jump" time.<br />Unless someone has moved or adjusted this linkage, the timing is allready at factory settings,and a timing light will generally bear this out.<br />The plugs may be causing a problem that at first, would act like a timing issue. Switchboxes on modern outboards are computer-controlled,and for the life of me, I don't know why,as they are not as reliable as some of the older CD designs, which were also much more fuel-effciant (which was the excuse to computerise them)--Fuzzy logic, if ya ask me,but I digress.Suspect compressiojn and the plugs first,second, and the fuel delivery system third.<br />If the timing linkage has been futzed with,then yes, all bets are off.<br />Good luck, and let us know how it goes.
 

Rdock

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Dec 29, 2002
Messages
9
Re: Timing an engine

Thankyou: OB and 12Footer. I have the repair manual from Mercury. I also have a friend who owns an auto repair shop. I think if I give him a Big Mac he will help me out. In the manual it says to insert Spark Gap tool in the #1cylinder plug boot. It says this tool can be obtained locally. Do you think from an auto parts place or a marine dealer. Can a timing light used on a car be used? Heres the problem I'm trying to solve.When I go on a high speed run and return the shift to neutral, the engine races up to about 1200 RPM. If I sit there for a few minutes it will eventually work it's way back down to about 800 RPM. At 1200 it really clunks if I shift. I noticed after I brought it in for service that the throttle cam and roller Position have been moved. If I change this to it's original position, will this change the timing.I can follow the steps in the service manual,but I would feel alot safer if I could get this timing thing figured out. My high speed is fine. I don't want to bother you with the reasons why I don't want to return to the dealer. Plus the 80 mile round trip. thanks for your time!
 

ob

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Aug 16, 2002
Messages
6,992
Re: Timing an engine

Rdock,The throttle cam and roller are factory preset to perform best under load with engine in water.If this setting was moved from original and there is a scribe line on cam for roller center I would return it to that position.The roller on the linkage should be aligned with a predetermined point and "just touching" when controls are in neutral.This insures your carb flaps are opening in time with ignition advancement.Could be that this setting is off a tad which would indeed have an effect on the idle speed in neutral by positioning carb flaps slightly open, as would an out of adjustment throttle cable trunion.The fact that engine will return to normal idle speed several seconds ,not minutes, after throttling down is indicative of sticky cable movement or carb linkage.<br />If you wanted to check timing as per manual specs a conventional timing light works fine.
 

Rdock

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Joined
Dec 29, 2002
Messages
9
Re: Timing an engine

OB Thanks again. Is it necessary to use a spark gap tool on the #1 plug wire. Can this part be purchased in an auto parts store?
 

joe Hetz

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Joined
Jul 2, 2002
Messages
22
Re: Timing an engine

My 94 75 hp.Merc. did the same thing and it was a matter of taking out the slack in the trottle cable. Its in the manual.
 

Yepblaze

Lieutenant Commander
Joined
Jun 1, 2001
Messages
1,686
Re: Timing an engine

Some of the outboard had a cold fast idle incorperated into the electronics. I don't know about your motor specifically, but it could be a sensor, thermastat, or something like that acting up.<br /><br />For a lot of us, once we set the timing we pretty much know it will stay set. Rarely needing occasional re-adjustment. Also the timing advance if not set correctly (exactly correctly) can cause piston failure.
 
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