There's a small pile of oily crud where the crankcase vent opens into the air cleaner, as you can see in the photo. Also, my air filter is very oily (the rubber parts look wet). Is this normal? If not, what does it indicate?

Not normal. Provided you have a valve cover with baffles unerneath the PCV and the crankcase breather, then oil should not make its way into the air cleaner housing. That much oil is indicative of blowby- either worn cylinder rings, worn piston bores, or worn valve guides.

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Casually looking for a Clifford hyperpak intake for cheap.

What Reed says is true, but there are a couple of asterisks. Even an engine in good condition will send oil to the air cleaner like this if the PCV valve is wrong or clogged, or there's another problem in the PCV system, or the crankcase breather no longer has an effective filter mesh in it, or (as Reed says) if you have an aftermarket valve cover that doesn't have a baffle below the breather.

Make sure you use the correct PCV valve. Many look alike, but the wrong one will give bad results. Some years ago I broke mine getting it out of the (original) grommet when I did the first-ever valve adjustment on my low-miles '73. Rummaged around in the trunk, found a PCV valve in a Chrysler box, tossed it on, everything seemed fine. But not too long after that, I was trying to diagnose a weird idle problem. I took off the air cleaner lid and the idle changed dramatically. Air filter -- nearly new -- was wet with oil, as was the inside of the air cleaner. And I could see smoke coming out of the air inlet fitting in the wall of the air cleaner. I was thinking the worst until I remembered having swapped that PCV valve. I went rummaging in the trunk again, found a known-correct new PCV valve, swapped it on, and the smoke disappeared. The replacement air filter did not get oiled down. Ya gotta have the right PCV valve or the system won't work correctly!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I do have the stock valve cover with baffles. Also, I have recently replaced the PCV valve (it's not the Chrysler brand, but it is a correct replacement, and it passes the shake test) and also replaced the crankcase breather. What I just realized is that I should have cleaned out the air cleaner when I replaced those items; I don't know if the oil is still building up or is left over from when the old PCV and breather were in place. I don't think I have significant blowby because I have vacuum at the crankcase breather with the engine running and PCV valve in place, and I'm not burning a significant amount of oil.

I guess the next step is to clean everything out, replace the air filter, and see what happens.

Good...
The shake test doesn't tell us anything here.
Good...
True.

If you're still oiling down the air filter, then yeah, it's time to think about rebuilding or replacing the engine. To buy yourself time, you can make an oil catch can and put it in the hose between the crankcase and the air cleaner.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm still (slowly) working on this issue--to recap, the crankcase breather is sending a mix of oil and unburnt fuel back into the air cleaner. The new air filter I installed 2500 miles ago is now full of oil, even worse than the last one.

I did a compression test today and all cylinders hold between 130 and 140 psi. Can I rule out blowby?

I also tried removing the oil filler cap with the engine running, and there was no significant suction or outflow of air through the filler opening either at idle or higher RPM.

When I removed the spark plugs for the compression test, l noticed that one of them had a significant buildup of crusty orange stuff, all over but particularly on one side of the side electrode. I had to scrape/sand off a lot of buildup to reset the gap to 0.035".

And finally I have an intermittent hiccup at idle.

Here are the plugs, arranged 654321.

If there's much unburned fuel in the crankcase gases, it suggests your fuel pump is faulty. Pull and smell the dipstick; does it smell of gasoline?
No.
That sounds like your PCV system is not working. Check for clogged or incorrect PCV valve, split PCV hose, clogged PCV port and passages at the base of the carburetor, or incorrect carb mounting gasket blocking the PCV passage.
Looks browner than orange to me. You're burning dirty.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yes, the dipstick does smell like gasoline, but I don't think the fuel pump is to blame because I replaced it not long ago. Initially I thought that fixed things, but it didn't.
I'll do that.
Could you elaborate on "dirty?" I should mention that most of my trips are short--a 6 mile, 20 minute commute to work. One other bit of info: I'm losing oil but not leaking it onto the ground. My exhaust is not visibly smoky but it does smell bad.

Oh, and I meant to ask you to elaborate on that. How can there be significant blowby if the compression is good?

Could timing be to blame? I have it set to 0 degrees per the fender label. Should I modify that for modern fuel? All of the original emissions equipment is still there, though obviously some of it may not be working properly.

Also, I understand the fuel in the oil is bad for the engine. Should I stop driving until i can get to the bottom of this problem? This car is my daily driver and I don't have a lot of time to work on it. If repair is urgent, I might take it to a shop.

If you're doing nothing but 6-mile trips, the choke's going to be on most of the time, and you're going to pour raw gasoline right down the cylinders into the crankcase. Under those conditions you need to be changing the oil and filter very often -- or, preferably, taking the car out for regular longer, higher-speed drives to get the engine up to full operating temperature, the spark plugs and combustion chambers clean, etc.

The other thing about all that cold-engine operation and oil dilution is that it greatly increases engine wear.

Change the oil and filter ASAP. Pour a couple of cans of BG 44K in the gas tank and fill it the rest of the way with gasoline. Figure out why the PCV valve isn't vacuuming out the crankcase and fix it. Set your timing to 5° BTDC (at idle, with the vacuum advance hose pulled off the distributor and capped so it doesn't create a vacuum leak). Then hook the vacuum advance back up -- one hose directly from the carburetor to the distributor, not stopping at that widget on the passenger side of the firewall, which you should ignore. Drive the car (note how much peppier it is with the timing advance and bypassed widget) until you're down to a quarter-tank, and then the fun part, do as the old Steppenwolf song says: Getchyer motor runnin' and head out on the highway. 60 mph til the engine's good and warm, then put it in 2nd gear and floor it -- up a hill, preferably. Don't fracture the speed limits or endanger yourself or others, but what you are doing is a good old-fashioned "Italian Tune-Up". Prepare to be amazed at the amount of brown smoke that flies out the tailpipe -- you'll see it in your rearview mirror. Keep on alternating 3rd-gear cruise and 2nd-gear haul for awhile; eventually the smoke density will decrease. Circle back to homebase and let things cool down awhile, pull the spark plugs and you'll probably find them a whole lot cleaner.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

hi sages- agree with uncle dans erudite analysis and check list. adding my 2cents- at least 5 times on different slant 6s i have solved this problem by cleaning out or replacing the hose to the pcv valve which was clogged up completely . uncle moe said it was coked up with charred oil sludge. this shuts off the vacuum suction which is needed for the engine to breath properly and dispose of the crankcase oil fumes. using the correct valve is critical too. have also found that the pcv valve like the thermostat is frequently replaced unnecessarily. like the timer on washing machines for you folks who have taken apart that bad boy. my 77 maytag still has the original timer and transmission. some have accused me of being a cheap.... and hurt my feelings. regards bob f

Just the excuse I was looking for. :-)
I don't have any vacuum widgets on the passenger firewall. Do you mean this widget on the side of the air cleaner? It seems to be the only vacuum component between the distributor and the carb.

Awesome, thanks. I'm looking forward to this.

Yup, the widget on the air cleaner is the one I mean. In '73 it was on the firewall; moved to the air cleaner for '74.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

If I pull the PCV valve out from its grommet in the valve cover, the valve sucks air. However, when I put the valve back in the grommet, there's no suction at the oil filler opening or the crankcase breather opening. It seems either there is some obstruction in the valve cover baffles that is blocking airflow, or there is air being pumped into the crankcase somehow. This set of symptoms is described inthis thread and over here. My engine has only 82K miles on it and the compression is 130-140 psi on all cylinders, but the car did sit in a garage for several years before I started driving it about 2 years/3K miles ago. One other tidbit: when I changed the oil today, the old oil was very dark, like chocolate syrup.

Separately, when I went to advance the timing I found the distributor is already as far counterclockwise as it will go (see picture) when the timing is at TDC. Do I need one of those VIM V103 wrenches as described here?