Trigger Wheel and IS ICM

[cef2lion]

I have a '98 STD and replaced my ICM from with one from an Interstate.

I'm not the original owner. Is there a way to visually tell if the original trigger wheel has been replaced with a 4 or 6 degree?

I have been following the annoying noise thread. I have a similar noise. I started thinking about the ICM and trigger wheel.

What degree is the OEM trigger wheel in a STD/Tour and IS?

[sandy]

If you use an IS ICM, then you only want a 4 deg trigger wheel. The IS ICM already has 2 deg of advance in the mid range.

[cef2lion]

Thank you.

From parts diagram the OEM trigger wheel is 30291-Mn5-000 for STD/Tour and IS.

If there are 4 and 6 degree available. What degree is OEM?

Also, if you take timing cover off is there a visual means to tell if you have the 4 or 6 degree wheel?

Since I have the IS ICM I'd like make sure past owner didn't put on a 6 degree trigger wheel.

[Momz]

When referring to the degree of a trigger wheel, wether 4 or 6 degree, it means an additional 4 or 6 degrees initial static advance over the OEM trigger wheel.

The OEM trigger wheel has slots/cutouts while the aftermarket wheels don't.

If you remove the first/outermost crank pulley, you should be able to see a stamped mark indicating either 4 or 6 degrees.

[98valk]

Thank you.

From parts diagram the OEM trigger wheel is 30291-Mn5-000 for STD/Tour and IS.

If there are 4 and 6 degree available. What degree is OEM?

Also, if you take timing cover off is there a visual means to tell if you have the 4 or 6 degree wheel?

Since I have the IS ICM I'd like make sure past owner didn't put on a 6 degree trigger wheel.

The OEM has squared cut teeth.  the aftermarket do not, they are more like pointed teeth.  Also there is also the chance the OEM was modified for the extra degrees.

to see the actual ignition curves of the ICMs, not really just 2 degrees more
http://www.timskelton.com/valkyrie/tech/trigger_wheel_plus_dyna3000.htm

[Robert]

The original trigger wheel is pretty much TDC since the timing is not controlled by the wheel but by the ICM it doesn't need to be advanced. The wheel is only a reference trigger for the spark.

[rocketray]

I used a 6 degree trigger wheel with a DYNA 3000 on an advanced curve and got into pre-ignition issues--I was only getting  some 60 miles per tank at something a bit over the speed limit...I would skip the trigger wheel