[40-A Twins]

I removed the intake manifold and checked flange flatness using the cast iron wing of the tablesaw and a feeler gauge.
Flanges were warped by approx. .006. I lapped the flanges with a sheet of 150 sandpaper by holding each flange down firmly against the tablesaw surface and moving in a circular pattern. Both flanges now have .003 gap at the lower edge.
I opened up the valve cover to check tappet clearances and found these to be the old solid type.
I measured each of these 2 or 3 times each to be sure - motor does not turn over smoothly when using the hand crank and is difficult to see when each tappet reaches the top of its stroke.
clearance measurement are as follows:
#1 .018
#8 .015
#2 .010
#7 .014
#3 .012
#6 .013
#4 .015
#5 .018

In my spare parts collection are nearly 3 full sets of solid tappets of varying lengths. I might be able to swap out tappets and get nominal .015 clearance at every tappet location.