Re Dr. Entropy's remark about RTV, I want to suggest that above all else, ignore the instructions on the tube, which say squeeze out a bead all round where you need a seal. Assuming of course there are not very irregular surfaces, that leads to far too much material, which then squeezes out. Not only is the result unsightly from outside, but much worse, it means that there is cured RTV floating around inside. I suspect that my oil starvation problems are the result of oil passage blockage caused by RTV. I found that a thin layer, applied with a finger, was effective with little or none to squeeze out.
Ken G, 1925 Rover 16/50 (San Francisco)