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OK mystery solved...

I thought I would post this in case it will help someone else. As I stated earlier, I had just replaced the generator and I thought I didn't tighten the chain enough and that the somehow it may have skipped a tooth on the gears and the cam and crank were out of time. This was not the case and I don't think it could ever really happen no matter how loose that generator is. By looking at the depth of the chain and size of the gears it would take more slack than the available travel the generator has to even come close to that chain skipping a tooth. Silver lining - I wanted to freshen up the engine compartment anyway so since I took most of it apart I'm doing it now.

Initial compression readings:
#1 - 50 psi
#2 - 120 psi
#3 - 100 psi
#4 - 90 psi
#5 - 120 psi
#6 - 0 psi
#7 - 30 psi
#8 - 120 psi

At the advice of a seasoned engine rebuilder near me, I adjusted all the valve lashes to 0.008" and added 4 'squirts' of oil to the low compression cylinders. I re-ran the compression test on those 3 cylinders and the only one that showed improvement was #1 which went from 50 to 90 psi once the oil was added.

I then fired up my air compressor and with both valves closed and the valve lash double checked I pressurized cylinders #1, 6 and 7 with the following results.

#6 which read 0 psi with both valves closed and the valve lash checked at 0.008", air coming out of the exhaust. No air felt coming out of the radiator hoses, nor the carb, nor the oil dipstick tube.

#7 which read 30 psi with both valves closed and the valve lash checked at 0.008", air coming out of the carburetor. No air felt coming out of the radiator hoses, nor the exhaust pipe, nor the oil dipstick tube.

#1 which initially read 50 psi then 90 psi after adding the oil with both valves closed and the valve lash checked at 0.008" no air felt coming out of the radiator hoses, nor the carb nor the exhaust pipe, nor the oil dipstick tube.

So in conclusion, my #6 exhaust valve is shot as is my #7 intake valve. Not sure what to think about #1 since I didn't feel any air coming out of the exhaust, intake, radiator hoses or oil dipstick tube.

Moving forward I'm going to replace both valves, seats and guides on the 3 troublesome cylinders and that should be that.

In retrospect, I think I may have caused the valve failure as I did not change the oil on a regular basis since I didn't drive the car all that much. When I did drain the oil, it was a nasty shade of gray and I remember thinking to myself, "hope I didn't break anything". Well hard lesson learned but I will be changing my oil every three months regardless of how much I drive the car.

So since I have to take the head off and the intake and exhaust manifold I thought I would send the manifolds off to get some new porcelain on them. Any recommendations for a good porcelain place?

Like I said, I posted this in case it will help someone else. So if you hear popping through the carb and lose power don't take the whole engine apart like I did ... check the simple things first.

Thank you all for indulging me and have a great day
-Crin

Number one is very likely stuck rings.

You could still have stuck rings or sticking valves that do not seat fully. I'd re-check the valve clearances and squirt some Marvel Mystery oil (about a tablespoon full) into the "bad' cylinders and then crank the engine with the spark plugs out and observe the valve action. If the valve clearance appears to change, it could be due to sticking calves, weak springs, debris under the valve faces, or the cam not on the base circle when the adjustment was made. Intake valves rarely burn, and no valves burn when an engine is sitting, and a head gasket leak is very unlikely to develop in an engine that is not running. If the engine ran well before the generator work, it should run as well after.

I'd check the valve action very thoroughly before pulling the cylinder head. If the valves are sticky or have debris between the valves and seats, running the engine at a fast idle, about 1,000 RPM, while squirting or dribbling something like Marvel Mystery Oil into the carburetor intake may clear up the problem. Doing this will generate a lot of smoke, so do it outdoors, preferably on a breezy day.

Thank you for the tips. I will certainly do that but here's the real problem ... blown gasket. Someone mentioned it early on and you were right on it. So cyl 6 & 7 were 'talking' to one another which explains why when pressurizing #7 air came out the exhaust (#6 exhaust valve was open) and when pressurizing #6 air came out the carburetor (#7 intake was open). Problem solved - I will definitely take the bits of advice and make sure I cover all the bases before I seal her up again.

Thank you again for all the great help.

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No question the gasket is bad... but on a compression test, it should only affect the two cylinders on either side of the break. When the engine is running, it can affect other cylinders to some degree by disrupting the mixture in the intake manifold. I'd look for evidence as to why it failed. Other sections of the gasket look suspiciuously sooty. The correct tightening pattern and procedure for the head nuts is crucial, and several retorqes are advisable to assure a good seal.

Glad you found the source of the problem. A blown head gasket will mess with the leak down results, as you found. If two adjacent cylinders are zero, or nearly so, on compression then very likely it's a blown gasket.

Now with the head off you can double check the valves you are concerned about. But my guess is a new gasket and proper torquing sequence (multiple times) will solve the problem. The head and block surface must be spotless before a new gasket. An old engine builder friend recommended 8-10 coats of copper gasket spray on both sides of the gasket when we did a recent valve job on a '52. We did not machine the head.

Thank you for the tip.

About 5 years ago I replaced all the valves, guides and ground the seats (which were replaced back around 2007 or so). At that time I had a gent that runs one of the best machine shops in my area come out and we placed a straight edge on the block and it checked out ok (which I fully expected since it was milled when rebuilt), then he took the head and milled it as well. I'm looking at the gasket which I got from Olson's gaskets and what they have on their website now looks different than what I have. Maybe they updated their design. I have also contacted Egge and Bestgaskets.com to see if I can possibly get my hands on an NOS one. I followed the torque sequence to a T and re-checked it periodically with favorable results. I'm hoping to either find an NOS gasket or maybe this new design from Olson's (pic attached) will last longer than 5 years. I don't think I have more than 500 miles on the car if that since the last time I replaced the gasket. I do agree that if you look closely at the gasket, it certainly looks like it wasn't 'crushed' enough. I also did not put as many coats of the copper gasket spray as was mentioned in the previous post. I may have put one to two coats per side.

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I don't know about 1936 but when milling a Packard head in general, one has to be very careful and do so only if absolutely necessary as there is a very little clearance between the valves and the combustion chamber. Was it checked for clearance after the milling?