From my diagram the upper 2 holes are spaced 1 7/8" vertically above
the centre. The lower 2 holes are spaced 2.019" vertically below the centre.

The upper 2 holes are 2 11/32" horizontally from the centre, although
the left dimension lines are not clearly related to the hole in question.

The lower 2 holes horizontal spacing is as you give 2.218"

The numbers are quite clear in my manual.

The holes size is given as 17/32"

Hope that helps.

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