That's hysterical!

I still can't believe that a "warped" cast alu. head could resist the clamping pressure of the head fixing bolts and studs.

Is it that the compression / combustion overpowers the clamping force?

Now those are numbers needing investigation!

Where did I leave those old books??

CalG

The aluminum Indian heads have larger bosses for the bolts than cast iron ones. Some neighbor boys were doing aluminum casting in the school shop, so I gave a spare 101 Scout head a coat of enamel to smooth it out and had them use it for a sand cast pattern. The reason was that despite Ted Hogdon's and other's propaganda, all the 101s (4) that I have ridden had abrupt combustion, not nearly as smooth as later ones. A 101 doesn't require nearly as much ignition advance as the aluminum head motors, apparently because the combustion is faster and each power stroke seems more jarring. I copied the later combustion chamber shape in the new one. It worked all right for a few miles, then the greater expansion of the aluminum crushed the bosses enough that the next time I ran it, the head bolts had lost their pressure and it blew the gasket. If you don't get too wild with the hold downs on the aluminum heads, I think there is enough material to keep it straight. Sort of OT, but that is the only time I have had to machine on an Indian head.

Bill

Edit- it occurs to me that I should have mentioned that I do not know the either the alloy of the original head or the one they cast. That may have contributed to the problem, but the Indian aluminum heads do have a lot more around the bolt holes.

I should have some time to work on the Indian a bit this weekend after a crazy work week.

It looks like there are a lot of opinions on what I thought would be a simple setup for those with experience.

Working on bikes for me is a stress free zone- sorry I got everyone worked up. I've read all of the posts and several good ideas come out of it. It seems best to use 3 jacks and clamp through the spark plug hole, using a rotary table, similar to donie's setup.

I just noticed there is a workholding area with no posts on this site- maybe this would be a good first post to be moved. It is fascinating to see how many options there are for the same task. That is one of the reasons I started machining.

I am a big fan of lapping warped parts flat . doing it this way there is no issue in set up it is progressive so you take no more than necessary and easy get your self a blanchard ground pc of steel or better yet iron much larger than part cover it with lapping compound , machinist hand book says use gas as lube but wd40 works fine . Try to cver the entire lap with your lapping to wear it evenly .

Thank you everyone for the advice, the milling setup with 2 jacks and a support, with a clamp through the spark plug hole made it easy. Now lapping should be easy to remove the machining imperfections.

I have an 8x10 piece of precision ground flat stock that I wrap 800 grit around and wet it with WD40 for lapping MC cylinder heads. Setting it on a large rubber mat on the work bench holds it in place very well so I can use both hands on the cylinder head.

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for starters i've never cut a head in my life, but that doesn't mean i don't have an opinion on the matter

not knowing to any degree how flat was good enough, i'd ere on the side of caution and make it very bloody flat.

making things very flat is not trivial, its difficult to do so when clamping pressures are involved....how are you going to hold it such that the clamping forces don't temporarily change its shape? I'd scrape it, be done in a hour and have it flatter than any process mentioned. Maybe an hour's too long, maybe the other ways mention are quicker, maybe the flatness i'd get with scraping is overkill.....i dont know, but (I think like the OP) i'm not doing it for a living, i don't have special set ups and would be approaching this as a one-of specialty job that had to be perfect and couldn't risk the part.

Just an idea from a guy who's never fly cut a head Is it that crazy?

neilert you did it, looks good. Zagnut, you REALLY did it