Flywheel swapping and timing question

[FCnLa]

When the light weight flywheel lost a magnet, I installed my stock flywheel to check the timing. The light weight flywheel has no numbers or marks on it. I am now ready to install the new light weight flywheel. Will this work?

Thanks, Paul.

[captcarb]

with a dial indicator.

Jim

[Jeff_G]

It should. The timing is determined by the relationship of the timer base to the crankshaft and block.

Any time you replace a flywheel you should check the timing. A degree wheel and dial indicator will do it. You can then mark the flywheel for future timing.

[FCnLa]

I used a piston stop (OMC part) and did the proceedure as per factory manual as far as setting the adjustable timing pointer to 0*. I was wondering about flywheel deviations where the timerbase picks up the signal on the flywheel.

[captcarb]

You need to mark your new flywheel and check the timing.

Jim

It doesn't matter a hill of beans where that metal insert under the flywheel is (within reason). When you find TDC and mark that flywheel you're set.

When you start the motor, if the insert under the flywheel is off it just means you'll be adjusting the timing base one way or the other more in order to compensate.

Once your timing light is showing the right setting on the flywheel everything is in synch.

While you're at it, find TDC for all the other cylinders and mark the flywheel for them also. Then take your calipers and measure 26 degrees clockwise (whatever you run at WOT) from each TDC marking for each cyl. Your flywheel should now be marked for both TDC and WOT timing. Now check each cyl with your light. Your flywheel is now indexed.

You may be surprised at what you find Then again the markings on the flywheel might be 100% symmetrical.

I use the dial indicator to find TDC. Set it up through the plug hole, turn clockwise, note where it stops, mark it, go past TDC, turn it counter clockwise, note where it stops, mark it, divide the distance between the stops in half, that is your TDC. The distance between where the indicator stopped both times should be small (.002-.003).

-BL

[captcarb]

Mercury recommends measuring the max spark advance directly with a dial indicator, and they publish that number. It is the most important setting. When the inline 6 came out they did not publish spark advance settings in degrees, only in thousanths of an inch before tdc. They supplied a guage that would measure it directly if the mech did not want to use a dial indicator. Why do you need to know where tdc is anyway? It is more difficult to measure and has no use that I can see. I don't use the factory pickup advance settings, I set it up to come off idle smoothly. If you want to know where tdc is then you can use your caliper and if it is off a little, it won't matter.

Jim

They should be the same, degrees on a flywheel or measuring piston movement. One is linear (straight line) the other rotational. That is interesting though and I can see doing it that way.

By "degreeing" the flywheel it just makes it easier to set for different settings and you need to find TDC to degree it. You can degree it with just finding TDC on one cyl but that won't show you the varying TDC points from cyl to cyl.

As far as coming off idle smoothly, are your referring to idle timing? I never set idle-off idle according to a number, always how it runs, idle speed, smoothness off idle etc.

-BL

[captcarb]

You open yourself up for tolerance build ups when you use several measurements to arrive at an answer that can can be measured directly. Try finding the max setting directly, and I think you will find that it is a lot more sensitive and accurate. I just mark the max setting for each cylinder.

Try it, I think you will like it.

If you want to try different max settings you can then calculate the value for a degree on the circumference of the flywheel. Or just eyeball it.

We agree on idle timing.

Jim

[ken medendorp]

Use a dial indicator find TDC on no#1 cyl.Then rotate your crank around so that you are at .150 BTDC.Then either adjust the pointer on the fly wheel cover to match up to the 25 degree mark on flywheel or make new mark.That's on a merc 2.5

[baddjonny]

Take a old sparkplug cuy out porcline thread inside I belive 3/8 fits get a peice of 3/8 treaded rod aprox 3.5" install with locknut .put stop in #1 plug hole other pulgs out to make life easy
bring piston almost to top, screw in stop keep turning flyweel by hand till piston hits stop screw mark flywheel now turn engine counterclockwise till it just hits stop again make a mark on flywheel now measure center between two marks .Now you know where TDC is .and everything else you know what to do .

no outlay for expensive tools. just comin sense.

Right on about "tolerances" adding up!

If you degreed the flywheel completely from just one TDC measurement you could end up off by several degrees in a cyl.

Measuring TDC on every cyl and then marking off degrees should be exactly the same as measuring BTDC in each cyl and marking the flywheel.

-BL