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Hi all, the bottom of my left head where the 10mm bolt goes in cracked off. Not sure why as I didn’t over torque the bolt. I’ve got a 75 gl1000 with 1100 block and 1000 heads and carbs.

Anyway, I have an 1100 left head I got for pretty much free. Was thinking to put my 75 cam in it, and bolt the ignition on the back by drilling and tapping new holes in the 1100 head. I’ll use an old ignition plate clamped down as a guide for the drill. Anyone ever do this?

Thanks for any insight on whether this’ll work.

PS I’m in canada so shipping a US 1000 head here is going to be 200ish dollars

I suggest you wait and a 1000 head will soon be listed in Canada. Worth the wait if you ask me.

Hmm, it seems like Sidecar Bob successfully pulled it off by tapering the 1000 ignition boss to fit the 1100 head which is beveled rather than flat. I'll give that a try and hope for the best!

https://www.ngwclub.com/forum/viewtopic ... 45#p721345

Note that I did not need to drill or tap any holes to make that work.
- The left head on a GL1100 has a steel cap to cover then end of the camshaft, which uses the same holes used for bolting the points case onto the 1000 head. Actually, you will find the same hopes on each end of both heads because they are also used for attaching the timing belt covers and the fuel pump.
- The GL1000 ignition plate that the points (or in my case the Dyna-S electronic ignition's modules) are mounted on is attached to the inside of the points case so the points case already has the holes for that.

You can see the holes that the points case bolts to on either side of the opening where the camshaft (not yet installed) will be in this pic


BTW, you should use the rockers that came with the cam you use and use the cam holders that came with the head.
And you want the left head and camshaft to match the right one.

Are the valve sizes the same for the 1100 and 1000 heads?

Yes. When I lapped the valves in my 1100 heads I found several that were slightly bent (you can tell when only one side of the valve becomes shiny) so I replaced them with ones from a 1000 head.

Shes up and running with no leaks! Filed my ignition module's boss down like Sidecar Bob, it took a few rounds of filing and test fitting but it works great. Also, didn't realize theres a slight difference in the 1100 and 1000 heads so probably good that I have 1100 heads on both sides now.

Thanks for your assistance fellas!!