Dear Jonathan Most of my work is rebuilding aged engines which often needs to re machine cases to fit new main bearing cups etc. I have a full machining plant to manufacture complete new Scott replica engines mostly for folks who wish to be more competitive in historic racing. I have all patterns and cases are cast in high strength LM25TF aluminium and machined at our plant in entirety. Blocks for sports engines are usually also made from LM25TF and the bores chrome plated and ground as per Yamaha TZ racers. I used to offer a service to TZ race teams to recondition barrels. Heads are also high strength alloy with a combustion space contour to match the piston shape and an ignition pre chamber similar to Ricardo principles. These are often supplied to replace Shipley heads that have become porous. Big ends have bearing cages. I have everything to fix engines and some other parts like undertrays. You can see what is available if you visit our website at http://www.mossengineering.co.uk and do not forget our free newsletter if you are not already on the list. Transfer Port Covers (TPC) Before fitting place TPC in position and see if it rocks. This would confirm the plane of the faces. You only need a little silicone to give a film of about 0.010″ thick as the gap will not exceed this. Standard DIY silicone sealant is fine and I have used it for over 30 years without problems. Kind Regards Roger
