So I've got a 472 in a 1971 caddy hearse I've been working on, and now I'm a bit confused. The car seems to be running rough despite being tuned correctly (dwell set at 30, timing set at 8b, new cap, rotor, points, plugs, wires, etc.)

My guess is that the car has too much oil in it. I did the typical put in about 5 quarts from a fresh oil change, then start adding 1/2 until I reached just about Full on the dipstick with the car full warm.

I suspect the oil is overfull for two reasons. There seems to be some oil running down from what looks to be the carb/aircleaner down the back of the tranny. (I can tell it's fresh since we Just put the rebuilt tranny in) and my other hint is that the dipstick says "use 4 quarts" right on it. I'm now thinking that this car (new to me) had the wrong dipstick in it, which was giving me false indications of the amount of oil in it.

Can anyone tell me how long that dipstick is supposed to be? Where can I source another one since noone seems to sell dipsticks other than generic replacement ones?

Thanks!

-Creech

If you change the oil and filter then add 5 quarts of oil then the level will be just right if it says full.
If added, an extra quart of oil will not upset this engine.
Idle problems can be tough. A sticking mechanical advance, vacuum leaks, crapped out carbonator or gummed up intake valves can all ruin your idle experience. Try setting the initial timing to zero instead of 8 before and see if it makes a large difference.

Crankcase capacity is 4 qts, so if you didn't change your filter, you added one qt too much. The dipstick in my 472 measures 20.50" overall length, measured from the point where it bottoms out on the tube. It's 18.75" to the "add one qt" mark and 17.94" to the "Full" mark.

Since you describe an overflow in the driverside valve cover, it could be possible that the oil returns are clogged up... I dont know, does the car give off alot of blue smoke?

Fresh engine oil running down the rear of the engine sounds like a leaky oil pressure sender.
I had a 500 years back that used oil. It had several skirts broken right off the pistons which were found in the oil pan years later. It was in a winter beater. Anyway, I used to add 6 quarts of oil with filter change and it ran just fine. No difference in performance between 5 or 6 quarts in the thing.