Poly Engine?

[Guest Georgeorge]

I have a 1955 Windsor Delux. I was told that the engine was a Poly, but I don't know how to confirm this information. The valve covers are curved around the plugs, not straight. If it is a Poly does that make the car more valuable, and if so by about how much?

Any information appreciated.

Thank you,

Mike

[Rusty_OToole]

If the valve covers are curved or notched along the bottom edge it is a Polysphere engine.

There is no such term in geometry as Polysphere, it is a name invented by Chrysler to describe a new type of engine related to the Hemi.

A Hemisphere is half a sphere. All the best high performance engines since 1912 have featured the hemisphere combustion chamber design. Chrysler was the first to introduce this type engine to mass produced cars in 1951.

In 1954 they brought out the Polysphere. This was a modified Hemi that was lighter, simpler and cheaper to produce. They continued the Hemi engine in the big New Yorker, Imperial, and 300 letter models. The Poly engine was used in the cheaper Windsor and Saratoga Chryslers, and other Poly engines were made for DeSoto, Dodge and Plymouth.

The poly engine is very close to the hemi in design and performance. Practically the only difference is the arrangement of the exhaust valve and the valve mechanism. By moving the exhaust valve they could eliminate one rocker shaft and also make the head casting smaller and lighter.

In back to back road tests when your car was new, the poly engine cars could keep up with the hemi cars up to 80 MPH. After that the superior breathing of the hemi allowed them to pull ahead.

In short, the Windsor model is the cheapest model in the Chrysler line. It is a little less powerful and a little less luxurious than the New Yorker but still it is one of the best medium priced cars of its time.

Today the Windsor is a little cheaper than the New Yorker but not much, maybe 5% difference.

[Guest Georgeorge]

Thank you for your information. This is making more sense now. I was looking for a carb kit, and the search tools said the '55 Windsor had a 2 bl, but mine has a 4 bl. The carb number showed up as the one on the hemi.

Thank you,

Mike

[Rusty_OToole]

The poly engine was the same as the hemi except for the heads. Same block, crankshaft, pistons etc.

Even the head was the same as far as the intake valve. Intake manifolds the same.

What they did was make a smaller 300 cu in poly engine in 54, when the big one was 331. Next year the hemi was enlarged to 354 and the poly got the 331. Finally the hemi was enlarged to 392 and the poly got the 354.

The poly came with a 2 barrel but a 4 barrel was optional at extra cost. They used the same manifold and carb as the previous year's hemi.

You can convert a poly engine to a hemi by bolting on the hemi heads and exhaust. This used to be a trick hot rodders did if they blew up their hemi and needed a new block.

Like I said, there is little or no difference in performance below 80 MPH so this trick is not worth the bother unless you are building a racing engine or hot rod.

[Guest Georgeorge]

Thank you again for your information. I have another question. This is a lost/purged tilte car. The VIN on the door is W5590888, but the VIN on the 1984 registration and inuurance card that I got from the seller is W559888. I remember seeing something that explains what the numbers stand for, but I can't find it now. I am sure that the 0 is just a "place holder" until they get to 1000, but am concerned about motor vehicle. I hope to get a title next week. Do you have any ideas?

Thank you, Mike

[keiser31]

The poly engine was the same as the hemi except for the heads. Same block, crankshaft, pistons etc.

Even the head was the same as far as the intake valve. Intake manifolds the same.

What they did was make a smaller 300 cu in poly engine in 54, when the big one was 331. Next year the hemi was enlarged to 354 and the poly got the 331. Finally the hemi was enlarged to 392 and the poly got the 354.

The poly came with a 2 barrel but a 4 barrel was optional at extra cost. They used the same manifold and carb as the previous year's hemi.

You can convert a poly engine to a hemi by bolting on the hemi heads and exhaust. This used to be a trick hot rodders did if they blew up their hemi and needed a new block.

Like I said, there is little or no difference in performance below 80 MPH so this trick is not worth the bother unless you are building a racing engine or hot rod.

Rusty...aren't the hemi pistons dome-topped for 1955?

[Rusty_OToole]

Oops the piston tops may have a different shape. The point I was trying to make is the Poly and Hemi are closely related, and many parts interchange.

[Rusty_OToole]

I don't know about the numbers but there are other members who do. You may get more response if you start a new thread like "Help me ID a 55 Windsor".

[Guest Georgeorge]

I did start a new post. Thank you.

Mike