Flywheel indexing

[Go Time]

Can somene please explain how to go about indexing a flywheel to check timing on each cylinder? Is it done using TDC for cylinder number 1 and then marked every 60 degrees or is each cylinder's TDC located individually? Is there a special tool needed?

[53w]

On my twin cylinder race engines this is how I do it.

I use dial indicator and thru spark plug hole and degree wheel find TDC on your first piston and rotate to your desired timing and dial it in. Remember the indicator travel from TDC and then check other cylinders if flywheel and ignition is good they all should be extremely close to same degree with timing light.

PS remove indicator before turning over engine to check timing. It is been proven to be vary hard on equipment if left in spark plug hole!!!

53w

[wired247]

Use the dial indicator to determine the TDC for each cylinder and mark the TDC on the flywheel. Use the highest cylinder to set the timing with. On mine I think its #4 that is 2 degrees higher than #1. I set the whatever the high cylinder is to 25 degrees advanced at WOT which means that #1 is 23 degrees BTDC at WOT. Had I set #1 to 25 degrees I'd have 27 on #4 which might not benefit me except to help lighten my wallet.

[Go Time]

I understand. I have noted the TDC is not the best place to index from as there is a lot of crank rotational travel with little deflection in the dial indicator and TDC varies some depending on the direction of rotation (CW vs CCW). Do you roll it back and forth to find the "center" of travel? Guess that's why the factory sets the timing pointer at .462 (or whatever it is).
How much variance is there normally Wired saw 2 degrees between 1 and his highest, (didn't say what the lowest was). I'm surprised there is that much "slop".

[dompie99]

A good advice from a S&F user (Criss Carson), he told me to run an extra wire or two between ECU plate to engine bloc and make sure that all the ground wires between cdi modules and ground are in excellent shape .

He also told me that a bad ground would make the CDI module to advance the timing if not grounded properly.

[Go Time]

I am surprized that there isn't more discussion/information on indexing flywheels considering you see many threads here recommending indexing and checking timing on all cylinders. My concern is getting the other cylinder timing marks on the flywheel accurrately enough to use them reliably for timing. If they aren't accurrate, the process is of little value.
My other question is, can you index one flywheel and then use it for timing all your engines? Then put the original fly wheel back on the engine after the timing is completed.

[rock]

I measure the flywheel's diameter then cut a thin strip of metal that exact length. I divide by 6 and locate the marks on the thin strip. Then I very accurately punch those points on the thin strip. Then I wrap the thin strip around the flywheel locating the ends of the strip on the TDC mark taping it in place. Then I punch thru the previously punched holes in the strip and this marks the flywheel locating the other 5 positions. I usually fill punched holes with a paint stick wiping off the excess. I also like to number the marks above the dot to make it easy to determine which mark you are actually seeing.I have found there are several different flywheel diameters meaning you would need several different strips to cover them all.

Rock

[Go Time]

That's a cool way of doing it Rock.
Where does the variance between cylinders come from? Flywheel magnet location tolerances or trigger construction variances? I would assume all cranks and blocks to be pretty percise...right?

[Dave Strong]

I index all cyl to .150", 25deg and check at max timing.

Dave

[powerabout]

Down load a compass card from web, blow up and print to suit your flywheel
Stick it on or just use as template.
As for timing indicator, piston stop is the only way.

[wired247]

Evenly spaced marks on a flywheel do not tel you anything about actual timing events in your motor. Crank throws can be off by a degree or more between cylinders. Each cylinder should be indexed individually on any performance engine outboard or automotive.

As far as piston stop versus dial indicator its a lot easier to dial in the TDC with a dial indicator and a degree wheel. New bearings versus old bearings make a huge difference too.

[rock]

That's a cool way of doing it Rock.
Where does the variance between cylinders come from? Flywheel magnet location tolerances or trigger construction variances? I would assume all cranks and blocks to be pretty percise...right?

I think the variations come from many places. All my method does is make the tdc mark at 60* intervals. I use it mainly to verify there is no crossfire.

Rock

[Slimm]

I index all cyl to .150", 25deg and check at max timing.

Dave

I assume the .150" is BTDC?

Slimm

[Go Time]

OK, so to do it right..you need to index each cylinder by locating and marking TDC with the flywheel that will be used with a dial indicator. Then locate and mark desired advance for each cylinder. Then check each cylinders timing.
Wired, what do you do about the fact that TDC when rotating CW does not match TDC when rotating CCW...just use the mean value?

[Slimm]

OK, so to do it right..you need to index each cylinder by locating and marking TDC with the flywheel that will be used with a dial indicator. Then locate and mark desired advance for each cylinder. Then check each cylinders timing.
Wired, what do you do about the fact that TDC when rotating CW does not match TDC when rotating CCW...just use the mean value?

From my experience you always use the TDC number from rotating the direction of operation. If you rotate CCW to pull the piston back down the cylinder, you need to rotate a little more and then rotate the crank in the direction of operation to take out any slack created by reversing rotation.

Slimm