How tight to set solid lifters

No, for the second time, mass does NOT matter. Take a piece of flat steel strip, 1" wide, 1/8" thick & 9" long.

Heat it up so that the temp difference between hot & cold is 100*. Measure the 9" length before & after heating to see how much it has expanded with the heat.

Now take a piece of steel 1" wide, 1/4" thick & 9"long. Repeat the heating experiment. The 9" length has expanded the same amount, but the piece of steel is twice as heavy......