how to time a recoil start engine?

[akwormy]

So I r ead the sticky on synch and timing and am trying to do it on my 68 merc 500

I guess I have two questions -

First question - how do use a timing light on a recoil motor?? I can't seem to get it...does it just take two people or what?

Second question is about the first timing event, (here is the quote from the sticky)
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"Timing Event One - throttle pickup.
As the throttle is advanced, the spark timing advances toward TDC and then to before TDC. As the timing is just passing TDC the 1st (minor)throttle pickup should hit and start to open the carbs. Use the timing light. Adjust the tang or trigger screw to make this a reality. All of them are speced different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win. Use the timing light with a friend cranking it to complete this setting."
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So - what exactly do I adjust if the timing is advanced too far at idle? I know how to adjust the max advance (with the stop screw) but I'm around 4-8 after TDC at idle and just don't know what to tweak or adjust to move it to 3-4 BTDC as suggested.

Thanks

 

[Yepblaze]

Re: how to time a recoil start engine?

I'm not sure what you are referencing for a timing procedure on this motor. Nor do I have the appropriate service data in front of me.

Before proceeding with any timing process.

You should initially check and make sure any timing marks you are using are accurate. By finding TDC and making sure.

I also am not sure your motor is timed while running. It may be timed statically with a continuity lamp or buzz box, in conjunction with the specified piston stop tool. (And perhaps others)

Mechanics use a test prop on a motor set into a test tank to enable a motor to be run up without propulsion while still having a load on it.

I've heard of others backing the boat on a trailer halfway into the water and running it up like that, but would never suggest that, as, if the bow stop failed it could cause severe damage or injury.

Where the motor idles is determined by the idle stop screw or cable adjustment. There is no specific idle timing point, but a good motor in reasonable tune will idle at the spec range if provided. If your motor needs considerable advance beyond spec to idle you have other issues and messing with link and sync may just compound your issues.

I suggest you find model specific service data. (a manual)

 

[akwormy]

Re: how to time a recoil start engine?

Talking about the sticky found here:

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

I have the manual, Thanks. But as many people stated in the thread about this sticky (here - http://forums.iboats.com/showthread.php?t=128495 ) the manual offers a confusing procedure.

Thanks - I already checked that the timing mark on the flywheel is accurate and it is. At least as close to accurate as I can tell without a dial indicator. I also check that the distributor pulley matches the appropriate mark on the flywheel.

This motor is a jet unit so a test prop doesn't help, but thanks for that.

I'm not saying my motor "needs" more advance than spec at idle- I'm saying it 'has" more advance than spec at idle and I want to adjust it to be in spec.

Both the manual and the sticky talk about adjusting a setting at idle so we're clearly not just talking about the idle stop screw. (sticky says adjust the tang or trigger screw...manual says retard the driver...of course in typical manual fashion that is an undefined term with no picture)

 

[akwormy]

Re: how to time a recoil start engine?

So to restate the question after the confusion.


How do you actually use a timing light on a recoil start unit? Will roping it actually give you enough time to see the mark? I tried it by myself, but pulling her over and trying to aim the light just didn't work. Will it work if I get a second body?


Since I couldn't get the timing light to work while roping it I went ahead and started it up - looks to be around 8 ATDC, clams sticky says it should be 3-4 BTDC.

How do I adjust this? (the sticky talks about a tang or trigger...the manual says retard the driver)

 

[Yepblaze]

Re: how to time a recoil start engine?

Your motor is not timed with an automotive type timing light.

And the idle speed is governed by the ignition timing and what ever the timing ends up to be at idle, is for the most part irrelevant.

 

[akwormy]

Re: how to time a recoil start engine?

Thanks, but if that's the case then I have to wonder why the sticky with 4,000+ views titled timing and sync of merc inlines would say:

"this basic procedure will work for all the 2/3/4/6 cylinder inlines from 1960 to 1988."

and a few sentences later this:

"Remove all plugs except #1, hook a timing light to #1. Then follow the narritive."

 

[Yepblaze]

Re: how to time a recoil start engine?

Yea, huh?

 

[akwormy]

Re: how to time a recoil start engine?

now that's funny!

cheers~