'63 544; B18D

Patrick (the 544) has been running okay for at least 40K miles after installing a pair of rebuilt SUs. Points and plugs have been refreshed twice a year.

Friday I took time to try adjusting the valves. With engine warm I followed the green book using .016 go and .018 no go to set the valve lash. To determine when to adjust #1 exhaust, I took out the plugs and hand turned the engine until #1 intake rocker just started to push the intake valve stem down. I worked my way down the exhaust valves and then started over at #1 working on intake after turning the engine until the #1 exhaust just started to open.

This process was repeated once and then valve cover replaced and engine started. Although the engine seems to be producing marginally more power (just my imagination?), a noticable valve tap has been added to the aural experience of driving the car. The tap is most insistent at idle and goes away entirely around 50 mph in 4th gear.

Today I went through adjusting the valves again as described above. Both #4 valves were a bit loose so I readjusted .016 go and .018 no go. The engine was started with much anticipation of regaining quiet valves. The rapping, rapping, rapping at my valve cover door continued though.

Is it possible to have the valves adjusted optimally and have a valve tap? If so, what is the likely cause of the tapping?

I regularly drive the car 150 miles a day. Would driving with the valve tap cause unnecessary damage to the engine? Is it better to tighten the valve lash to .015 to reduce hammering for now?

Thanks in advance,

Joe M