Re: oil pickup on a 39 120 - more issues

Posted by David Grubbs On 2014/7/10 12:52:49

Put the oil pickup and pan back on. The cause of all of this work is due to accidentally putting Rotella oil in the engine instead of non detergent. The car ran fine for several weeks, and then sputtered to a stop a few blocks from the house. I towed it back and started working on it. The carb is working fine, but the spark was weak. I changed the coil, cleaned and re-gapped the plugs and pulled the distributor. It has the two part points, which were too tight. I cleaned them and reset the correct gap. I suspect the problem was gunk that got knocked loose with the detergent oil, which kept several cylinders from getting good compression.

Put the distributor back in, guessing at the timing, since the goal last evening was to run the engine at 1500 rpm or so for a half hour with new Rotella with one quart of ATF to clean out any remaining gunk. Got the engine running, but missing on one or more cylinders. It sounded like a motor boat when I held my hand close to the tailpipe.

This morning, I pulled the oil gallery covers and sprayed all of the valve stems with PB Blaster, then rotated the engine, and sprayed again. Did this several times, and let it sit several hours. Got my antique compression tester out (it's about 50+ years old), pulled all of the plugs and tested each cylinder. Results are:
#1 100
#2 70
#3 100
#4 90
#5 100
#6 65
#7 65
#8 80
The variances may be due to the old rubber on the compression tester not making a good seal. I was pleased to see that the valves do seem to be working, at least in some fashion. I will go back this evening and button it up so that I can run it again. I will also pull the starter so that I can set the timing accurately (not one of Packard's best ideas!!). My question is, what it the best way to free up the valves on the low compression cylinders, without removing the head?