Troubleshooting the new (to me) truck...

[shuttermutt]

A few weeks ago I picked up a 1968 CST LWB with a 327, factory air, TH400, Posi, and other goodies. The body's a little rough, but nothing out of the ordinary. I'm having some ignition and/or fuel troubles, though that are driving me wild.

Here are the symptoms:

- Runs best when cold (choke on), but a little miss can be heard. The miss gets worse when warm.
- When warm, she "stumbles" a little off the line. In other words, the truck hesitates and cuts out for a second or two when throttle is applied from a dead stop.
- On occasion, the truck is hard to start (almost like it's flooded) when allowed to warm-up then shut off for 5-10 minutes. When it does start, a cloud of grayish smoke comes out the exhaust.
- Good oil pressure except at hot idle when it drops to nearly zero and a slight knock can be heard from the bottom-end.
- Starting today, the truck is throwing an all-out hissy fit. Now it's backfiring pretty regularly through the carb when under a load and I'm hearing a "ticking" noise that varies with engine speed and sounds like it's coming from the distributor. If I put it in drive, take my foot off the gas, then tap the throttle it will backfire once through the carb then rev up relatively smooth.

These problems have been getting progressively worse as I've been driving the truck. What started as a little miss has manifested itself into a truck that doesn't like to run. The engine was supposedly rebuilt a few years back by a competent mechanic, but I'm treating it like a completely "unknown condition" engine. Here's what I've done so far:

- Replaced cap, points (yes, I know... HEI is on the way), condenser, plugs, and wires. BTW, the plugs looked okay, but were carbon fouled.
- Confirmed the timing at 8-degrees.
- Replaced the fuel filter, air filter, and PCV valve.
- Visually inspected for obvious vaccum leaks.
- Verified that the power valve (or whatever that damn thing is called on a Quad) wasn't stuck.
- Verified that the secondaries were closed all the way.
- Literally drowned the carb with B-12. Once while running and again while shut off (and left to sit overnight).
- Confirmed that the distributor looks okay. The base plate can be moved, the rotor doesn't turn backwards, nothing is cracked/missing/loose, the springs are on.
- Confirmed that the vaccum choke pulloff is working as it should.

Note that the engine doesn't ping (detonation) or smoke (other than described above).

My thinking is one or more of the following:

So, does anybody have any ideas what I might be looking at? Stuck valve? Broken spring? Flat cam? Possessed carb?