Trevor, no modification to the frame was required. I just sat the engine on a block until it was in the right position. The engine mounting lugs were milled down to the same width as the M20 lugs and some 741 and M20 engine plates were cut and shut (welded together). The dynamo chain mounting was also milled off as there's not enough room for a 741 dynamo. I scalloped the rear engine/gearbox plates to accept a miller dynamo behind the rear cylinder.
I used a standard single spring M20 clutch (again with 2 plates removed). The triplex chain teeth were machined off the engine sprocket (just leaving the dynamo sprocket in place and an M21 sprocket was suitably machined and welded in place of the triplex teeth in line with the clutch sprocket. Likewise a 741 dynamo sprocket was welded in place of the miller belt pulley. Ron
email (option): ronpier@talk21.com
Well I've never noticed the tank get any hotter than from the heat rising off the engine, which I imagine can only slightly warm the petrol and can that hurt? What about riding in the Sahara desert?? It was quite common practice during the 30's and I've actually used a 1938 BSA C10 tank. I made up oil pipes with Imperial fitting for the tank and US fitting for the oil pump. Ron
email (option): ronpier@talk21.com