OK, after rechecking, it appears I was wrong, I'm mixing up the J and 2J bolt
pattern. Here's what I now believe is correct:

The top 2 are spaced 1-7/8" vertically and 2-11/32" horizontally from center.
The lower 2 are spaced 2.019" vertically and 2.218" horizontally from center.

GWE

Grant Erwin wrote:
I have the BP manual. You are correct, there is a bolt pattern which I
never noticed before because it is so small and sort of smudged. Even
with 4X magnification I can't really satisfactorily read it. If you
don't mind, would you confirm these?

All 4 holes are spaced 1-7/8" vertically from the center of rotation.
The upper two holes are spaced 2-11/16" horizontally from the center.
The lower two holes are spaced 2.218" horizontally from the center.

Thanks!

GWE

David Billington wrote:

The hole position details are in the BP manual I have. If you want I
can scan the page and email it to you or maybe you can find the manual
online. Its page 5.2 in my manual.

Grant Erwin wrote:

A J-head is held on by 4 1/2" bolts, as many of us know very well. I
am planning to work on my extra J-head, which is at the moment braced
up on a rolling platform. J-heads are devilish awkward things to
move, lift, or do anything with until they're properly mounted. But I
have to work on this one, so I'm planning to mount it on an
inexpensive engine stand, procured today for $25. First woops is it
won't mount on the 4 fingers of the engine stand, they don't go that
close together. So I'm going to make another mount plate, my engine
stand mount plate just uses regular 1½" pipe.

I'm wondering if any of you guys know the bolt pattern of these 4
bolts. I stuck a piece of steel under there and punched it using my
transfer punches (there are those ubiquitous transfer punches again)
but the pattern is really crooked and I figure someone knows the
actual designed values. Anyone?

GWE