Re: Valve Tappet problem
Yes, I have encountered this problem on engines whose valves have been ground so many times that the heads are almost flush with the deck of the block. That translates to the valve stems now being "too long". The valve heads normally sit above the block. Are yours sunken to the point of almost being on the same plane as the top of the engine block? If so, that is why the new tappet bolts seem to tall. The real solution is to have new valve seats installed in your block, which will pull the valves back up where they belong.
However, since that is an expensive and time-consuming job, your next best bet is what I have done in such cases. Take the new lifters to a machine shop or use your own equipment if you have it and have the appropriate amount of "meat" removed from the bolt head, (not from the bottom of the tappet!) so that you have some wiggle room for adjustment. That gap varies in people's recommendations depending upon the camshaft and personal taste. At least 0.012" seems to be safe and will not result in a noisy engine or burned exhaust valves. If you have a Model "B" camshaft, the gaps are wider.
You can also have a little metal removed from the mushroom valve stems in conjunction with taking meat off the lifter adjusting bolt. Then you spread your losses and don't weaken one more than the other.
Marshall
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