Not only is work progressing well on the TR6 project, but it looks as though work is progressing well now that everything is looking freshly painted and shiny. I have been in charge of the spray painting in two pack black and Cherine has been ably picking around all the machined surfaces and the plated bits on the engine with a brush. As usual everything is primed with Red Lead Oxide which gives for a nice long life, all the cast bits are finished in satin and all the pressed steel bits in gloss. Fitting and final assembly is to follow shortly.
Work is also well underway with the 3.8 MK2 Jaguar. The owner and I had been aware for some while that the engine was a little tired, but an extremely loud knocking had brought the car’s story to an abrupt conclusion. This is not an entirely unknown phenomenon on the 3.8 Jaguar: The engine had been originally developed by increasing the cylinder bore size of the 3.4 litre unit and by fitting liners to the cylinder block. Jaguar had initially given suitable clearance for the larger pistons by machining a chamfer on the edge of the combustion chambers in the cylinder head. It wasn’t long however before someone decided that producing two different heads for the three available capacities of engine made no sense. Therefore the chamfer was deleted from the cylinder head and machined instead on the 3.8 litre pistons. What this means of course is that it is absolutely essential to make sure that the cylinder head and the pistons in a particular engine are compatible. In the words of Michael Caine, “not a lot of people know that”. This car is a 1961 model and has a c1965 cylinder head. All was fine until the big end bearings developed a little extra clearance and allowed the pistons to start contacting the head in a somewhat noisy fashion.
Also on the subject of cylinder heads, I have been attending to one such item from a 1935 Derby Bentley which is suffering from cracks on three of the exhaust valve seats. Despite this the head is still very “saveable” and well worth doing since few good original items seem to have survived. The sensible solution will be preheated gas fusion welding which will make a nice permanent job and will also allow plenty of scope for any future repairs which might crop up.