There is little doubt that Chrome rings are superior to cast rings under certain conditions, and this difference is reflected in the price. Chrome rings are more expensive by a factor of two or more.Well it's all clear as mud to me, maybe I should start a poll on grey iron or chrome plated.
Well I brought all the parts indoors and let them stabilise at 20degC and remeasured everything, there was a slight improvement but not much.I opted not to spend several hundred dollars on "new" cam towers due primarily to the fact that they can be replaced, (with some difficulty), once the engine is placed back in the car and running. If at that time I observe an unacceptable level of ticking, then I'll make the decision... or not... to spend the roughly $600 bucks to replace one side (drivers) of the cam towers. I believe the cost to replace the cam itself would add an additional several hundred dollars.
I would suggest buying a replacement #5 cam tower (your right side) on ebay. You will likely be able to find one closer to spec and without the deep scratches visible on yours. I was able to find 2 cam towers at a reasonable price from 2 separate sellers and I was pleased with their condition.Well I brought all the parts indoors and let them stabilise at 20degC and remeasured everything, there was a slight improvement but not much.
Given that the cams and bearings are relatively easy to change, I have no ticking sound or symptoms and that it will be the best part of £1000 to change (bearing towers, camshaft, rocker arms and maybe shims), I will take your advice and reuse what I have. The worst that will happen is that I'll put off the expense for a year and have a project for next winter.
Put the valve stem in your drill motor and spin the valve in a scotch bright pad. The valve will come out looking new.I then went on to try to clean up the valves, I will leave them in this oven cleaner overnight, but don't have a good feeling of success. The main ingredient is Potassium Hydroxide. Does anyone have a suggestion of the best way to do this?