I'm looking to buy a 36-1 trigger wheel to mount on my harmonic balancer and the options I have to choose from are 4", 6 3/4", and 8 1/4" in diameter. I'm not near my Jeep right now, so I was wondering if anyone could tell me what size will match up best. Basically it needs to be slightly larger than the balancer I believe.

 

The OD is 7-7/16", as measured by tape measure, so the 8-1/4 looks like what you need.
Another option could be to have the notches milled into the OD of the balancer itself, looks like there's lots of meat to be able to do that.
Are you installing MegaSquirt? Keep us posted, I'd like to know how it works out for you.

 

Thanks for the info! I didn't think about notching the balancer. I may try that on an extra one I have first.

And yep I am gonna try and install megasquirt. I have it built already, but I didn't realize it would be so difficult to get a tach signal in. I plan on controlling the ignition after I get the hang of fuel, so I'll need the trigger wheel setup instead of using the coil.

I'll start a thread in a couple weeks when I'm home from school for awhile and can dig in. This forum needs some megasquirt posts. Lol