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Thinking about changing the head on my 1940 Super to a high compression head from the standard compression head. Any valve clearance, or other issues to be concerned with?
Thanks Todd

If you are going to use a Packard issued HC head then Packard already engineered it to work on your application.
M<any heads have the same bolt pattern etc and will fit: 40-50 Cust 8 356, 48-54 288 & 327, 54 359 aluminum. If any of these heads has not been resurfaced they should be OK but the smaller cubic inch 288's may give high compression and tend to knock/detonate.

As far as I know, none cause valve interference as long as they have not been resurfaced too much. How much is too much?? Only determined by installing the head and putting dum-dum above the valves to see if they hit.

None of the heads will make a hot rod out of your long stroke engine

Thanks for the response. It has been sitting around. May be doing a valve job, so thought I might give it a try.
Thanks again.

Have a tube of Permatex, non drying Prussian Blue, that I have not used in years. Might try putting that on the edge of each valve head. Doing an initial torque down, crank engine by hand, pull head and see if there is any blue on chamber?
Or not a workable idea? Valves my open a bit further at running rpm?

I would not expect any valve float on this low rpm engine, but at low cranking speeds hyd lifters may not be full

I think the dum dum or even modeling clay laying on the top of the valve is better. That way by how thin the dumdum is squished you can get an estimation of just how much clearance there actually is rather than just if it hits. Not having the lifters pumped up could give false reassurance the clearance is adequate so by using the dum dum you could estimate if there is enough clearance after the lifters were full -- or else use the stem grinding gauge to temporarily replace a few lifters. Unfortunately with that method you would have to move the gauge and do the test over a few times.

Thanks