Sounds like a bad ground. Check all ground connections. Especially starter to rear plate/bell housing. Often too much paint in these locations.

Dean, as Ric has pointed out, check all your grounds again. Knowing how through you are, you have probably already checked these numerous times, but that is good info. Something we have run into, basically the same problem, we have found the starter solenoid is bad, drawing all the juice, but not delivering it to the starter. Something else to check for is too much initial timing. If your distributor is still stock, check to insure the centrifugal counter weights have not fallen apart inside the dist. base and/or stuck in place?. If you have a modified dist., remove it, have it checked for proper operation, insuring that it does not produce too much advance. The advance weights in the conversion dist. can also be of concern?. You probably have or have access to an actual amp draw gauge. These were an old type tool/instrument used to measure draw of the starter by laying it on the cable, watching the amp draw while trying to start the engine?. Obviously, just trying to add a few things to check. Also, another simple though, take a good set of battery jumper cables, go from the battery to the frame and engine. This will add extra grounds wherever you select, and can give you a quick response to see if it helps the concern?. Hope to see your car at the Dells!

Thank you for the extra suggestions. I have one of those cable overlay gauges somewhere, so I'll have to dig it out. It seems like the slowness is irregular, which causes me to be concerned about a bad field in the starter itself. I did find some corrosion on the + terminal. My solenoid is the old style with a button, but actuating it manually didn't change the response. Cleaning it helped a little, as did putting my best 6V battery in place. I also noticed that as I try multiple time to start it, when the oil pressure come up to about 20psi it gets easier to turn over. So many things to check. Thank you again.

Well, I dug out my cable style amperage gauge and it drew full scale 400 amps while trying to turn the engine. I actuated the starter both from the start button and directly at the solenoid switch. No difference as the starter is laboring to turn the engine over. The needle goes over full scale as the engine labors to turn over. To me that adds up to a field coil with an open, so that the starter cannot maintain full speed and get the engine to light off. A trip to the rebuilder seems in order. Thank you for the replies I received.
Dean

PROBLEM SOLVED:
I got the starter back from the local rebuilder.
The battery cable stud was damaged internally and the wire to one of the fields was disconnected. He installed a new stud, resoldered the wire to the field coil, rewraped both field coils and installed a new bushing. Now it works like a champ. Probably the idiot owner overheated it.
I made an offering to Electra for forgiveness.
Dean

Was that Electra 225 or Electra Estate?

Hope that is NOT Sophocles' Electra.

Persistence in trouble shooting, and determination to complete !!! Good job Dean!

Good to know that HET members are well read.

Well this starter is kicking my rear.
The problem has reappeared.
I just can't get the engine to turn over fast enough to light off and the voltage on start drops to 4V. The book says I need 5.
This doesn't provide enough voltage to the coil, and it barely fires. It pulls 400 amps on start. The book says it should draw 160- 180.
When I got the starter from the shop, the tech said it has 2 field coils. The Hudson manual says it should have 4 poles (page 6-2 of the 1951 Mechanical Procedures Manual), and I assume this refers to the field coils.
I wonder if I have a binding problem? I think I have a 1956 block because the codes read: 532500 CWC 2 with 262 head 304621 2 CWC 8202. The starter is a MCH 6204.
The transmission is apparently original to the car, an H-50 single range Hydramatic.
Could it be that transplanting the 1956 engine into a '51 Hornet is causing a conflict with the earlier tranny and that is producing drag?
I read that the 1955 and 1956 crankshafts are 1/2 shorter at the crankshaft flange. Could this be producing a binding at the starter drive?
I am out of Aces.
Dean

You DID check the grounds, right? Battery (+) ground strap connects to engine at some point, right? And the (--) cable is a 6-volt one (3/4" dia.) not 12 V? (Sorry, just throwing in some "obvious" possibilities, though you have probably progressed way beyond these in your quest.)

Yup, when I had the starter rebuilt the first time, I replaced the cables with 1/0 stuff and I added an additional ground between the block and the body at about midway on the block. I guess I could move the block end closer to the starter though, and check for corrosion at the battery to body to block at the front .

Dean, I think the later blocks have a 7 digit part#. Yes, the 55-6 crankshaft is about .500 shorter. I would think your car has to have the correct crankshaft or otherwise it wouldn't work at all. If it has the 5-6 crank, it would have to have an adapter/spacer in between the crank and flywheel. With the inspection cover removed, looking up into the bell-housing, you should be able to see the adapter, if equipped, and if it has the adapter, it would also require you to have a 55-6 auto flywheel. The torus bowl bolts are 3/8th's fine VS. '51-'54, 5/16th's fine. Out of curiosity, have you retarded the timing trying to compensate for the hard crank?. My Dads '56 engine did the slow/hard crank thing, but that problem went completely away when we converted it to 12V. He wanted a modern stereo and accessories.

A NOTE. We have found when using the 55-56 block, it is so much easier to use the '51-'54 crankshaft in them, unless you are racing and/or using it for severe usage. Using the '51-54 crank in the later block makes the trans, starter and so many other parts all standard. You still need to change the frt. and rear engine support plates, change the location of the oil dipstick to the rear., change oil pans, and probably the water pump, depending on your application.

Doug:
Thank you for this notes. You're right the block number is 5325000. I left one zero off.
There is no adapter between the crank flange and the torus cover. The bolts are 3/8".
I have retarded the spark in the past, but thought I could advance it after I got the starter back from the shop. Looks like I should retard it again.
I think the long term solution is to rebuild the GMC 700R4 I have in my parts bin and buy the Wilcap kit and change over to a 12 V system.
BTW my dipstick is located 4 inches back from the front end of the starter, between the starter and the block. So it looks like I'm half way there.
Dean