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I gapped all the rings (including the oil rings) to at least .015 at the bottom of the cylinders. I only had to replace the bearings on #8 (it was about .001 oversize via use of platicgauge). i'll pull the pan again, and check everything again, maybe I should put the old bearings on #8 and give it a shot. I don't understand how the engine cranked at a decent speed with the head off, and cranks very slow with the head on. Is there any way to check how hard it should be to turn the engine by hand before I put the head on for the third time?
Thanks in advance
Casey Rog

Casey,
Lets go over this, you replaced a Rod bearing and rings just in one cylinder. Than with the head off it cranked over fine. (Correct?)
Next you put the head on with the spark plugs installed and it cranks over slowly. (Correct?)
If both are Correct, I would look at the cables not able to carry enough current, next does your battery have enough juice and last is your starter good. If the starter is not using all the brushes, I would think without a load (Head removed) it would look like it is turning over the engine just fine. But if a brush or two isn't making contact and a high load it would turn slower.
This is what I would look into, maybe I'm missing something here but if you had a problem with the head removed than I would say look at the rings and bearings.
Wes

I hate it when these kinds of problems arise.

Is the battery fully charged?

Did you assemble the engine with lubricant on the bearings and cylinder walls?

Are you getting oil pressure?

(o{}o)

I only replaced one set of rod bearings, but replaced all the rings. All the carbon has been removed from the ring lands, all the new ring were gapped. The car started fine with the old rings, but was burning oil. Since I had to replace the trans, I figured I do the rings.
With the head removed, the car cranked fine, with the head on,it cranked very slowly. I rebuilt the starter a couple years ago when I got the car. The battery is fully charged.
Tonight I dropped the pan and pulled the head. I am going to pull all the pistons again check the fit of the piston in the cylinders at a time.
How tight should the piston fit in the cylinder? And how easy should the engine turn over by hand?
Thanks in advance

Casey, the correct piston fit is covered in the '51 Workshop Manual (1951 Packard Service Manual) under "Engine' section. See pages 14 and 15. There are a couple of methods described there for checking tolerance.

I recently put new rings in my 288. Put a "NEW" battery in the car at the same time. The car cranked incredibly slow. I cleaned all wire connections and even replaced the solenoid. I took the starter apart 3 times before having the brand new battery load tested and I found out that the new battery was bad.
As far as turning by hand (this is only my experience) it was extremely dificult to turn the engine over by had to get the last 2 pistons in. And the pistons fit tighter in the cylinders than I expected. There was no sliding them in. I had to drive them with the butt of a hammer.
Not trying to qestion your ability, but since you are taking it apart again, make sure the rings aren't in upside down. My car used a quart every 50 miles. When I pulled it apart I found the previous owner had installed all the rings upside down.

Thanks for the reply.
I took the pistons out again and rented a piston ring groove cleaner. Soaked the pistons in Zylol, cleaned the grooves really well and put the rings back on, and put the pistons back in the cylinders. The new pistons are move up and down better now, but not as free as the originals (with 80,000 miles on the rings). Engine cranked great without the head, slower when I put the head on. However, I still have to put the pan back, and it seems the engine cranks faster now. Hopefully fast enough to start the car. The whole thing about rings is to make sure first that they are gapped properly and that the grooves are shiny clean. By the weekend I hope to start the car.
Thanks, everyone for your responses. Next, I get to see if the 1953 trans I put in the car works.