Radiator Caps - What's the Difference

[Frosty]

These two old Pontiac radiator caps look nearly identical except for the plating finish. However, there are other differences. These belong on different year Pontiacs. Can you tell what year each cap belongs on?

BTW - I am now the proud owner of the one on the left.

 

Something tells me that this thread is going to be right in 31pontiac's wheelhouse!

[Ringo64]

Is the one on the left slightly smaller than the one on the right? Can't tell if that is just the photo.

[Frosty]

Yes, the one on the right is just slightly taller. Not by much though.

[Last Indian]

59 minutes ago, Frosty said:

Yes, the one on the right is just slightly taller. Not by much though.

Ok good one Frosty, i’m Stumped! The one on the right is definitely a 1926-27, but I’ve seen the one on the left as well on a 26-27. Which doesn’t mean much because people don’t always have correct pieces. 

Still the one on the right is a correct 26-27 model cap. So what is the left for?

They could be two different sandcasting molds, but you indicate a different car is involved.

Edited April 18, 2018 by Last Indian

[JUSTA6]

My guess is the one on the right is the older of the two. Brass face cast head dress.  Yours appears to be plated.

[Frosty]

1 hour ago, Last Indian said:

Ok good one Frosty, i’m Stumped! The one on the right is definitely a 1926-27, but I’ve seen the one on the left as well on a 26-27. Which doesn’t mean much because people don’t always have correct pieces. 

Still the one on the right is a correct 26-27 model cap. So what is the left for?

They could be two different sandcasting molds, but you indicate a different car is involved.

 

46 minutes ago, JUSTA6 said:

My guess is the one on the right is the older of the two. Brass face cast head dress.  Yours appears to be plated.

Correct JUSTA. The one on the left is chrome plated. The one the right is nickel and brass plated.

Now look at the top and middle photos. Count the feathers behind the head dress. The chrome one has 7 feather from top to bottom. The nickel one has 8 feather. Also, the feathers on the chrome one come closer to the edge of the cap than the nickel, at the base.

Now look at the base under the heads. The chrome one was a wide base and narrows to meet the head while the nickel is more mushroom shaped - narrow at the bottom and wider at the top.

Therefore, the chrome piece is the correct radiator cap for the first-year, 1926 Pontiac.

The nickel/brass piece is the correct radiator cap for the 1927 model year Pontiac.

[SPRINT 6]

FWIW and as pointed out Size, Shape and Feather Count differ between the two years. Sadly seeing early Pontiac's at shows anymore is almost as rare as the Caps themselves.

My related pin board ; 

https://www.pinterest.com/mrbigbluesky/pontiac-sky/

Cheers

 

Edited April 19, 2018 by SPRINT 6

[Frosty]

I am totally with you Sprint6.

Even more rare are Oaklands. Fortunately one member of our club owns a 1910 Oakland. At our 2016 Dustoff, I was lucky enough to ride in it. It is the second oldest car I've ever been in (a 1903 curved dash Olds being the oldest). He won Best of Show with it too.

 

[Ringo64]

Funny, was thinking the slightly large one was going to be the older one. I just didn't think it would be old by only 1 year.