'55-60 Block Dowel Locations
 

A PY member asked for help with dimensions of dowel pin locations on the rear of '55-60 blocks, so I took measurements off one of my Harvey Aluminum blocks, which are very accurate copies of a '60 Pontiac block. In fact, it's possible that PMD machined them, after Harvey cast them, using Pontiac mold patterns. I'll attach a sketch of my results.

Note the potential for tolerance-buildup, which could detract from the precision of the results. After sketching the layout, I searched my notes and found that I had instructed the machine shop to do a "skim cut" on the pan rails, so .005" is probably a good guess. I also found that my rear main clearance is a hair over .004", so the "+/- .0015" shown on the sketch for crank location should actually be +/- .002".

Rather than just sending this info to one person, I decided to make it available here, in case someone else might find it useful. Also- if anybody has actual block blueprints, it would be nice to post the blueprint, and delete this empirical stuff.

Thanks much Jack
The following dimensions from Taff2 match up well enough for me to go ahead and start fabbing.(measure twice cut once) Diagonally from the crank centreline to the centre of the dowel is 7.4375".
Horizontally from the crank centreline across the rear pan rail and then vertically to the dowel centre is 6.875".
Vertically from rear pan rail to dowel centre is 2.80". Dowel diameter is .495".These measurements were taken with a steel ruler so could be a smidge out.

Thanks much both of you guys.

Attached is the SB mopar pattern as seen facing the trans. also attached is the 61-64 t400 adapter(which doesnt have the crank centerline dimensions in relation to the dowels)

Bruce