How thick is EE 16 carburetor insulator? My aftermarket choices are 1/4" and 1/2".

I have spark at idle and swapped wires and plugs to see if I have interment issue at higher speed. No change. Verify distributor next. Must be valve or oil ring issue.

Thank you Howard.

OK. I will drive it. Seems strange that only number two is carboning. Must be borderline valve seal. I'll give an update later this spring. Thank you for your help. Any comment on oil filter cicuit?

oh - one more question. My car has the original in series oil filter to lifter circuit. Is it advisable to put the oil filter parallel kit on?. Do I really want to drill and tap a hole in the block? Existing circuit contribution to noisy lifters? Oil pressure shows good. oil pressure picked up after lifter circuit or?

done. registered. The valve story will continue until solved.

ok. done. a partial story anyway. Thank you all for Packard help.

ok. #1 cyl 92 psi. #2 88 psi #3 93 psi. Then the inlaws pulled in the driveway and that is far as I got. lifters toward front of engine are complaining so I think I have sticky valve(s). All plugs look great except for #2 - all wet and carboned up.
Will be traveling so I think I will soak with PB blaster or Marvel Mystery while I'm gone. Then I will decide how to get under her and reach up and adjust the valves (while running or cold? possible? What is recommended). Drove it quite a bit today. Seems like lifters are worse maybe because of carboning in valve - not sure. Also I have a rapid tic toc by the fan in the front like the water pump or timing chain circuit. This car is just starting to loosen up and showing her personality. oil circuits need some help maybe. Any further advice is welcomed.
Maybe I should do a full valve job and get it done right? 90 psi is borderline no? Drives nice - has power - no blue smoke. Heck - its an old wonderful car.

Thanks for the advice. Could I possibly have a little rust in the exhaust valve guide causing sticky valve? (repaeated caution in the service manual) the problem increased when I took it out of storage and yes the car went through a number of short start stops in the cold when it was first delivered to me. How would I free this up? Low compression. not zero. I gotta find a better gage. You can hear a small exhaust periodic pop just less of a non- perfect idle. Will continue to post as I go through this.

My new 1940 acquisition: Flat 8 Number 2 cylinder is seeing spark but has wet plug. Valve or piston assy seal obviously. All other cylinder combustion looks good. What to do next? Valve adjust or pull head? Burnt valve potential? lap valve required? no gas in oil accumulation. no blue smoke. Car has 50K mile and most likely engine not rebuilt.
How do I go about this efficiently and effectively?