I know you don't often want to put the accelerator to the floor while running in park. But just say you did. Would the starter engage? Is there anything that is supposed to prevent that from happening? I think I heard a brief grinding noise...oops.

When the engine is running vacuum at the start switch prevents starter activation.......Bob

And if that fails the charging generator will prevent starting.
Willie

Appears I may have a malfunction. I did floor it in park and I did hear a bad sound. I said a bad word and immediately took my foot off the gas. Seems to have not caused too much damage. I started it several times afterward and it sounded normal.

Contrary to popular opinion, pre-'61 Buicks did not require the driver to press the accelerator all the way to the floor to engage the starter (although to hear my godmother starting hers across the street while I was growing up, you'd think it did!). The '55 owner's manual says that with a cold or warm engine, you should depress the accelerator just far enough to engage the starter. The only time the accelerator was to be put on the floor when cranking was if the engine was flooded.

Yep about a 1/3 pedal does it. It really is great, pretty much takes care of the fuel priming needed in the summer anyway.

57Roadmaster75:
Rustysheperd has it right, you only need to push the accelerator pedal far enough to engage the starter. If the engine is already running, the starter should not engage in a properly maintained car if the accelerator pedal is suddenly pushed to the floor. However, if you hear a grinding sound, this is the starter gear trying to engage with the ring gear of the turning flywheel. Buick incorporated two systems to prevent this. The first is that the starter switch on the carburetor has a steel ball that is held by engine vacuum while the engine is running and this prevents the switch contacts from closing. In case this switch is not calibrated properly, the other system is the way a starter switch to activate the starter relay on the starter motor is wired. In this system the starter relay coil winding is grounded by way of the armature terminal of the generator. Ground potential only occurs when the generator armature is at rest or turning very slowly. Otherwise the armature terminal has a positive voltage on it and the starter relay will not close the contacts to operate the starter.
However, if the accelerator pump of the carburetor or some other engine system is not working properly, the engine might nearly stall when the accelerator is suddenly pushed to the floor. Pushing the accelerator wide open will drop the vacuum in the carburetor circuit so the carburetor starter switch may operate. Next, if the engine nearly stalls, the potential on tha armature of the generator may be close enough to ground potential to cause the starter to engage. This will cause a grinding sound that sounds awful.
I would check to be sure the accelerator pump in the carburetor is functioning properly and also that the carburetor gaskets are correct and tight to properly route vacuum to the starter switch.
Good luck.
Joe, BCA 33493

I found that the plunger in the carb start switch was installed 180 out. It had the the groove facing down. This was preventing the steel ball from rising up. Switched it around and now things are behaving as they should.