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Old 03-10-2022, 09:40 PM
Mark O'Neal Mark O'Neal is offline
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Default 1956 287ci

I have a buddy searching for a 3.250 stroke crankshaft, if anyone has been hiding one from human eyes for 50 years or so.

Any help in locating one (or three) would be appreciated.

If there is a better place to put this, please let me know.

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Old 03-10-2022, 10:04 PM
tom s tom s is offline
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try these guys.Tom
https://www.pontiacparts.net/

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Old 03-10-2022, 11:09 PM
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Bill Hanlon Bill Hanlon is offline
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Noticed your title "1956 287".

There weren't very many 1956 287 cubic inch engines. More likely that your friend has a a 1955 287 cubic inch engine or a 1956 317 cubic inch engine. Whichever, he needs to be sure before looking for a crankshaft because the Master Parts Catalog says the 1955 engine uses crankshaft part number 518047 and the 1956 engine uses part number 521602.

No, I don't know the difference.

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Old 03-10-2022, 11:16 PM
Mark O'Neal Mark O'Neal is offline
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Thank you.

They don't appear to have any engine parts.

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Old 03-10-2022, 11:17 PM
Mark O'Neal Mark O'Neal is offline
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Quote:
Originally Posted by Bill Hanlon View Post
Noticed your title "1956 287".

There weren't very many 1956 287 cubic inch engines. More likely that your friend has a a 1955 287 cubic inch engine or a 1956 317 cubic inch engine. Whichever, he needs to be sure before looking for a crankshaft because the Master Parts Catalog says the 1955 engine uses crankshaft part number 518047 and the 1956 engine uses part number 521602.

No, I don't know the difference.
Neither do I...but as long as it's 3.250....we'll make it work. We have to make spacers anyway.

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Old 03-10-2022, 11:27 PM
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I bought a 57 crank from them.Call and ask.Tom

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Old 03-10-2022, 11:28 PM
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Thread copied to Big Pontiac Parts Wanted classified forum.

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Old 03-11-2022, 12:30 AM
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FWIW, both the 1955 287 engine, and the 1956 317 both list a 3.25 stroke. The difference is in bore size, stroke was the same for both years. I have no idea if the main, and rod journals are the same size.

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Old 03-11-2022, 12:46 AM
tom s tom s is offline
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They are 2.5 mains.I used those main bearing in my 303 SCCA RA V engines.57-58 got bigger and 59 went to 3in.Tom

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Old 03-11-2022, 01:02 AM
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‘55 - ‘56 = 2.5”

‘57 - ‘58 = 2.625”

‘59 - up = 3”

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Old 03-11-2022, 10:55 AM
tom s tom s is offline
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FYI,most of the early cranks were forged but not all!Tom

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Old 03-11-2022, 03:29 PM
Mark O'Neal Mark O'Neal is offline
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Quote:
Originally Posted by Mark O'Neal View Post
Neither do I...but as long as it's 3.250....we'll make it work. We have to make spacers anyway.
Doesn't have a crank, but does have a short block. That may work out too.

Thanks.

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Old 05-02-2022, 04:14 PM
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Quote:
Originally Posted by Bill Hanlon View Post
Noticed your title "1956 287".

There weren't very many 1956 287 cubic inch engines. More likely that your friend has a a 1955 287 cubic inch engine or a 1956 317 cubic inch engine. Whichever, he needs to be sure before looking for a crankshaft because the Master Parts Catalog says the 1955 engine uses crankshaft part number 518047 and the 1956 engine uses part number 521602.

No, I don't know the difference.
The difference is probably the pilot bore for the dual range hydramatic pilot shaft. Stratoflights do not require a pilot bearing.

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Old 05-02-2022, 04:59 PM
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but some '56 Pontiacs had dual-range Hydra-Matics.

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Old 05-03-2022, 12:15 AM
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Quote:
Originally Posted by tom s View Post
FYI,most of the early cranks were forged but not all!Tom
I can't prove it, but I believe that all '56 and '58 cranks were forgings; all other early cranks were castings.

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Old 05-03-2022, 07:36 PM
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PM sent

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Old 05-03-2022, 08:20 PM
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Jack,I can tell you forsure they are NOT!I bought one myself and had to take it back where I bought it.Also the one Kaase got was cast.They were both 57-58,dont know about 55-56.Tom

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Old 05-03-2022, 08:48 PM
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I can confirm that a 518047 is forged, and has a counterbored pilot hole.

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Old 06-25-2022, 01:50 PM
flat-bill flat-bill is offline
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Default '56 motor parts

Are you still looking for a '56 crank? I have one that is probably std/std. Maybe some other stuff too. Send PM. Billk

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