I just picked up a B20/M41 out of a 1968 P1800 and have started tearing it down to asses the condition, and slowly, as funds permit, rebuild it for my 122.

I just got the package inside the garage and broken down to the major components (head, block, trans) and have a few initial questions I was hoping someone(s) can shed some light on.

First up, the head has a thing-a-majig bolted to the right front, near the thermostat. I can't recall seeing one in pictures, and my (B18) head has a block off plate bolted on there. What is it?


Next . . . anyway to tell what kind of head this is? Being allegedly from a '68, it pre-dates fuel injection, and the freeze plugs in the injector holes seem to indicate that is accurate. It had been converted to a weber downdraft carb. Are all non-FI heads the same? B20B's?


Thirdly, whats the little square-headed brass screw near the crank gear?


. . . and this stud on the top front of the block? Something from an A/C setup? There was a double-stack of pulleys mounted to the crankshaft, which seems to indicate SOMETHING else was being run via belt.


Last question is regarding the cylinder bores. They all measure to just a shade under 90mm right at the top. For the most part the bores are nice and smooth, with some cross hatching that is not really visable with the camera flash. However in places there is discoloration on the right and left sides of the bores. It looks like surface rust, but is not seen on all the cylinders. It can be seen much easier than it can be felt. Something to be concerned with if I'm planning on having (at a minimum) a hone job done?