[Bill Hanlon]

Originally Posted by Onestone

it uses only two gears

It would help if you could tell which 2 gears. Can you change gears by moving the shift lever while driving?

[Jack Gifford]

Great work on the horn switch!

[Onestone]

Next update here:

My original fuelpump was leaking fuel and oil. I replaced it with an electric Hardi pump, but I think this type of pump is maybe called different in the US (?). ... Its maybe also known as "Mitsuba fuelpump", used in many other old cars.

Technically its a diaphragm pump like the original one, but electric driven and it has an internal pressure sensor which makes the pump stop when the fuelpressure against the carburetor gets high (above ~0,35 bar). This way the pump always pumps exactly to the need of the carb - so when the float chamber is full it stops automaticly, and starts again as soon as more fuel is needed.

Another advantage is it fills the float chamber before cranking, which makes starting much easier after not moving the car for a longer time. These pumps are used on many oldtimer restorations to greatly increase reliability.

This is how this pump looks:


Preparation of the mounting location, also the integrated holder and mountplate I welded:


Ready mounted and wired:


Wiring of this pump is very easy, it just needs ground and +12V ignition. Everything I touch at this car I use new accessories, so here of cource also new hoses, new screws, new filter etc. came in too. The filter is will not stay fo very long, I used this transparent one to check if too much dirt is coming from the tank. After some driving later I will replace it with a metal one.

Also a litte optical beautification came in - I replaced these tail lights (I think they weren't original Pontiac ones...?):


...with new ones I got from a dealer in IL :




Coming up next: new crank case ventilation and pertronix ignition

[Onestone]

...I found something the craftsman updates from November 1955

So vacuum officially needs to be disconnected, and the port on the carb must be taped during timing.

[Onestone]

Thank you so much for your help!

I already thought the same way - how to determine which gear 2500rpm at 35mph is

So what I already did is measuring the circumfence of my tires -> it's 223cm, which is almost exactly 87,76" - as shown in the shop manual for 7:60-15 tires.

I did today some pictures from the differential and the transmission - because I was hoping to find anything on the housings that tell me the ratios. See the pictures attached.

On the differential housing I found a number called "A25 50" - Google didn't know anything about that. And on my transmission there is a plate which says "D56 - 46365" - is this a 1956 dual range Hydramatic on my 1955 maybe?

I was already thinking how can I get the exact rear end ratio, I will do as you suggest below and tell the result here. I will also do another test drive and measure the exact GPS speed in both gears with my phone.

Thanks again for all the help - I really appreciate it!

[Bill Hanlon]

Originally Posted by Onestone

Thank you so much for your help!

I already thought the same way - how to determine which gear 2500rpm at 35mph is

So what I already did is measuring the circumfence of my tires -> it's 223cm, which is almost exactly 87,76" - as shown in the shop manual for 7:60-15 tires.

I did today some pictures from the differential and the transmission - because I was hoping to find anything on the housings that tell me the ratios. See the pictures attached.

On the differential housing I found a number called "A25 50" - Google didn't know anything about that.

And on my transmission there is a plate which says "D56 - 46365" - is this a 1956 dual range Hydramatic on my 1955 maybe?

The "A25 50" is actually a casting date for the diff housing. And the zero is not a number, but a mark in the casting that sort of looks like a flat head screw. There is another such mark at the front of the casting date. GM did this on many major cast parts like engine blocks, heads, transmission cases, etc. After 70 years they can be hard to read.

The remaining A255 decodes as ...
A = January, B = February, C = March, etc
25 is the 25th day of the month (if less than the 10th only one digit is used)
5 is the last digit of the year, 1955

Originally Posted by Onestone

And on my transmission there is a plate which says "D56 - 46365" - is this a 1956 dual range Hydramatic on my 1955 maybe?

Likely, but my Pontiac decodes only go thru 1955. The '55 would be a "P55", but remember in 1956 Pontiac used two automatic transmissions, the dual-range HydraMatic like you have and the Strato-Flight Hydra-Matic (also known as Controlled Coupling Hydra-Matic or Super Hydra-Matic). Those would have a different letter/number on the plate.

I've updated my spreadsheet with your tire size. When you get me the rear end ratio I'll load a new one.

[Jack Gifford]

Bill- the only failure I would expect of a hydro's clutches would be failure-to-engage. A failure-to-engage the front clutch would cause 2nd & 4th to act as neutrals. (Ask me how I know...)
Perhaps he should try driving it in 3rd up to a speed where it would try to shift into 4th and see what happens?