I know this has been covered here but I can’t find the original article with the search words I’ve been using. So I thought I’d post pics of the pieces I’ve collected and ask a few questions because this is a common topic.
The pieces shown are what I’ve collected to run the early tach gen on my xJ engine. The head has tested well at the machine shop so it is undergoing some minor machining: I am taking this rear intake cam shell to be checked while the shop has the head; it extends through the large opening on the smooth cam covers but has to substitute for the shorter XJ intake rear cam shell.
I will have to drill and tap three holes to bolt the tach generator to the XJ head. Does anyone know how deep these holes should go and or have a good photo to orient the tach drive for drilling?
I believe there are also a few bits to connect the tach gen drive to the cam, and some sort of operation is required to adapt the newer cams to the peg drive on the tach gen. Also may need some drilling in the center of the later cams, again how deep should one go with that hole.
Hope this is helpful and if anyone wants to cross link the earlier articles that I could not find I will not be offended.
It seems to me that if you simply want a working tachometer it would be much easier to modify the tach to trigger from the ignition pulses rather than modifying the head to use the potentially problematic and inaccurate tach-gen system.
Ditto, Mike. And if the presence of the tach generator is desired for appearance purposes, stop at the point of drilling/tapping the mounting holes. I’m using the tach you modified for me and bolted the tach generator (without the drive dog) in place for originality purposes only. (The tach works perfectly, by the way).
Won’t have go very deep if you’re just hanging it there for appearances. By the way, you might be able to gut an old tach gen case if the stickout stuff forced you into expensive machining on the cam, for example. I can’t remember what that area looks like). Anyway, here’s a photo of the rear of a 3.8 head. I mounted the generator after the engine was installed (dumb move), so no decent photos.
