Hi George, my main bearing stud holes in the base plate are through holes. My intentions are to fashion the new bearing castings and their gunmetal 3/16” risers, soft solder them together, drill through and team to 5/16”, put witness marks on for reassembly. Next, unsolder them, fit on reamer and superglue the lot in their correct positions on the base plate with the reamer inserted. Then, using a 5 BA tapping drill, drill through bearings and risers from beneath the base plate through original threaded holes. Finally remove them and open the holes in the bearings and risers to 5BA clearance. Can you see anything wrong with this method.
Secondly, I can’t get my head round the inlet and exhaust arrangements. The plans indicate two 3/16” bore inlet glands bolted to valve chests and a 3/16” o/d piece of copper pipe with a 90° bend in it. One flange is tapped 3/16” 40 TPI, the other is 3/16” plane. Next their are 3 castings for pipe unions/flanges, one elbow flange and 2 straight through 1/4” flanges. I presume the elbow and one 1/4” bore flange straight through are for exhaust manifold joined and exited by 1/4” copper pipe. That leaves a 3/16” bore straight through flange which must be for the remaining inlet. So how does the bent 3/16” pipe get to the second flange. It’s not long enough for one and two the second flange needs to be split and and a 3/16” stand off pipe inserted between the split. Unfortunately I can find plenty of photos of the compound engine but none for the twin that I can make sense of. Could you send me some photos to help?
ps the half holes in the base plate will either have half round sections of brass soldered in or I may fashion the outer bearing risers with a lower lip to cover the holesinset into base plate. The centre one will be largely invisible.
Jerry C.