As I am stuck at home during the continuing covid days I thought I would write abit about cylinders (mostly C1) and an interesting historical story I uncovered during my research.
Much earlier in these pages I included descriptions and photos of both C1 and C4 cylinders. I also compared them to the -46 cylinder off the helicopter engine. I have been rooting through my trailers looking to put together a few sets of cylinders and I thought I would give you a look at what I found. First, most cylinders are available in either steel bores (usually new black cylinders ) or chrome cylinders ( reconditioned with chrome bore to bring them back out to standard dimensions).They are usually painted primer red. These cylinders are choke bored meaning they have a taper of about.007 being bigger at the bore opening.They are very similar to the original aircraft type cylinders made by the Wright Corporation in the prewar years, but probably don't have the nitride hardening of earlier Wright cylinders.. Both the black and red cylinders have spark plug coolers and cast bosses beside the rocker boxes. The aviation cylinders (photos 3&4) are easily identified by the large size of the spark plug coolers and by the fact that the cast bosses along side the rocker boxes are drilled and threaded to accommodate baffles.
While some 7 cylinder (760) Wright aircraft engines apparently did not use any spark plug coolers, most did. They were a repair item and could be replaced on C1 engines. Note that C4 engines did not use them.
C4 cylinders were designed to significantly increase cooling. The increased fin area amounted to 50% on the head and 100% more for the barrel. The barrel no longer was machined with fins but instead an aluminum "muff" was slid over the steel barrel and this design was used on many other large radial aircraft engines of the time. At the bottom of the next post are photos of a steel barrel of the C1 style with machined cooling fins, and a much larger radial cylinder from a bomber, with aluminium muff on the cylinder base.