From my manual the J head and 2J2 head seem to have the same bolt
pattern for mounting.

Grant Erwin wrote:

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