Originally Posted by robertc82

I might go ahead and take it al the way off. I know I am supposed to file the hole counter clockwise but how much?

Originally Posted by SoCal-305

I did the tone wheel mod this morning and it was pretty easy and straightforward like Mathew stated. There are 60 teeth on the tone wheel but there is an area that is missing a tooth or two to give a reference point for the ECM. In other words don't just count the teeth and do your math based on that.

Here are my measurements for people who are interested:

-there is up to 1.0mm of rotational play in the stock tone wheel mounting configuration that could amount up to 0.5 degrees of timing difference going from truck to truck. I'm surprised the tone wheel has so much play considering its importance to the operation of the engine. This is maybe why some people who install the Rokktech sensor experience some knocking as they have a more advanced stock tone wheel mounting?

Radius of tone wheel = 105mm
Diameter of tone wheel = 210mm
Circumference of tone wheel = 660mm (using the formula 2x"pie"xR)

2degrees = about 3.7mm of circumference movement, I shot for 3.5mm so I wouldn't overdo it.
Each tone wheel tooth looks to be just over 4.0mm in width, possibly around 4.25mm. Mathew, maybe you're just over 2 degrees of advance by a 1/3rd of a degree if you used the tone wheel tooth as a reference point?

The dowel pin slot is 22.5mm from the center and I calculated I would need to remove 0.75mm from the counterclockwise side to get the adjustability I wanted.

I started the truck when I was done and there is a bit more rattle to it, more like how a standard older diesel engine would sound. I will test it after I'm done with this post.

MikeyB, I notice your post in where Rocktech said they remove 0.080" from the thickest part of the sensor to get the adjustability they want. Does that mean the sensor tip actually moves 0.080" over the tone wheel or does the sensor rotate and the tip moves more than that? The reason why I ask that is 0.080" of movement over the tone wheel would only account for an advance of a little over 1.0 degree. Thanks!

Originally Posted by Superduty

Something doesn't add up here. Rocktech is claiming 2 degrees with 80 thou removed from the sensor. From what I can tell, removing 80 thou from the sensor is going to advance the sensor face 80 thou. 80 thou = 2mm. I'm assuming the sensor still sits flat in its holder and isn't pointing in a different direction.

The dia of the tone wheel is 210 mm, so the radius is 105mm. The advance in degrees is thus

sin(adv) = o/h = 2mm/105 mm adv = asin(2mm/105mm) = 1.09 degrees

To get 2 degrees of advance, we would need:

sin(adv) = o/h o = sin(2degrees) x 105mm = 3.66mm or 144 thou.

Now, people slotting the tone wheel dowel:

sin(adv) = o/h o = sin(2 degrees) x 22.5mm = 0.785mm = 31 thou.

The easiest way to do this exactly might be to measure the dowel pin hole and then carefully drill it 62 thou oversize. 31 thou is not much material. Judging by the comments the tone wheel people are making (more rattle) compared to the sensor mod people, I'd guess that they are advancing the timing more.

I find it interesting that there is play in the dowel hole. If I had a truck that was getting poor fuel economy, I'd advance my tone ring as much as I could.

One mroe thing: there are 60 teeth on the tone ring. That means that each *tooth and space* is 6 degrees and if the tooth and space distances are equal, each tooth is 3 degrees wide, as is each space. Thus to change the timing 2 degrees, the sensor would have to move 2/3rds of a tooth.

I think the Rockteck sensor is actually advancing the timing by 1 degree.

I think I'm going to adjust my tone ring for fully advanced timing with the stock dowel pin hole and then mod my sensor to advance the timing by 1 degree. I don't want a rattly engine.

Can someone give me good, conclusive MPG or EGT numbers ?

Originally Posted by lawnmaniac883

How do you relieve tension off of the belt...i know there is a self tensioner but cant figure out how to defeat it?