Anyone fab up an external crank trigger?

[bszopi]

I can draw something up as well.... I might have a look at one of my cranks here in the next week or so.

[Guest]

I know at one point there was a rather long thread on 3rdgen.org about the crank triggers, started off discussing N* crank trigger, but also a lot of discussin on the 660/OHV I4 crank trigger wheel as well.

[bszopi]

Bringing the subject back from the dead... Messed around with a spare crank, a dial indicator and AutoCAD 2004 and came up with the following picture... Marty, if you can verify this, that would be great! I want to try to do a 3D version of it kinda like my intake flange I did awhile back...



I just noticed I need to add the measurement of the small piece of metal between the reference notch and the first timing notch. I'm pretty sure its 0.10", but I'll get it on the drawing sometime to make it easier to fab up.

Once its verified, I can probably make the CAD file available for people if they want to take it to a machine shop to get plugged into a CNC machine.

[RacerX11]

I'll try to dig out my 3 spare cranks this weekend and verify these measurements. We should also include the three bolt holes that would mount this to a stock damper, since that is the most likely method of attachment.

Marty

[bszopi]

I can do the bolt holes as well. To reply to your question in the Site Discussion area thread, I just looked at my crank timing gear and noticed the dot marking TDC is offset from the crank key. I was just going off the crank key as TDC, but obviously its not. I'll have to change that tonight. Thanks for pointing that out!

[bszopi]

Well, if my calculations are right, it looks like TDC is between 28.8* and 30* CW from the crank key. Does this seem about right?

[RacerX11]

I guess what I was thinking of were these two diagrams showing the DIS system. It shows the crank sensor lining up exactly with the first notch before the reference notch (labeled 6 in the picture) for cylinder #1 TDC.

Marty

[bszopi]

Alright, after talking to Marty for awhile tonight, we really didn't come to much of a conclusion. He is going to try to figure out exactly where the stock sensor hits when #1 cyl is at TDC. But, as we discussed, it really won't matter too much because once this is mounted externally, the sensor will be mounted in a different location and possibly orientation than the stock. So what I'll probably end up doing is making a drawing similar to the one above and reference where the sensor should be mounted in relation to the reference notch. From there, the mounting holes can be changed to match where you will locate your sensor.

Does that sound about right Marty? Oh yeah, and here is the updated drawing...

[bszopi]

Even though it seems that no one else really cares about this... Marty verified the location of the notches and sensor with #1 @ TDC, so I made changes to the drawing to match.

[RacerX11]

Holy crap that's huge! BTW, that 2.85" bolt circle is for the FFP pulley...the stocker is slightly bigger....but I couldn't measure it.

Marty

[Guest]

so that last drawing is of actual size of the disc that needs to be made to make an external setup?

Trust me you two aren't the only ones interested in this setup. I find this stuff fascinating.

Nice work. Thanks for taking the time to do this.

[bszopi]

Well, the size may not be exact if you print it out. But the measurements are exact. I plan on making the CAD file available in the near future so someone can take it to a CNC operator and have one milled out.