I think i broke rear main bearing

years ago in Australia
small country garages were issued with a main cap repair set by Chrysler Australia
and a special set of bearings that covered the normal oversizes plus a range with a couple of thou variation that came from the production line that "fixed up" bad tolerances, in problem engines

these caps were all slightly too tall
all had been honed with a precise offset one way or the other

in a situation like this a country garage would
spend some time with the kit and either the bore gauge or plastiguage

find the cap that fitted best
find a combination of upper and lower bearings that fit best which may or may not be a matched set. the one of "best fit" in the cap i think...might have that wrong..!

use a manual (flat plate glass and abrasive paper) method or a machining method to take off a few thou from the mounting face of the cap to get top/bottom clearance

if you could achieve 0.0005 to 0.0015 thou clearance at 3 places across the top surface of the journal put it back together and off you go 500 miles on break in oil. job done using chrysler parts when your nearest main dealer is 100s of miles away.

these kits have not existed since the 70s

you don't have to align bore...... its just a sensible way to do the job if you don't have the special kit...! (or access to the incremental oversize bearings)

i used a front cap from a 318 in my hemi 6 its a big fat thing compared with standard, cap 1 fitted nice in cap 2 position, (cap 2 was sprung, loose in the register) so i could fit the 318 cap in cap 1 position which accommodated its excessive thickness.

i had 4 318 caps to choose from
i chose the "best-fit" one and we got away with a hone i had the time i didn't have the money and i didn't have access to any hemi 6 main caps. there were only 4 of the motors in the country 1 in a museum and 2 in cars + my near scrap rebuilder, which, with much head scratching and swearing, I successfully tuned into a decent motor

needs must....and occasionally you get lucky


Dave