# Reading a Build Sheet



## s27519 (Sep 11, 2018)

Received my build sheet from PHS. Notices that the "ENG or MOTOR UNIT NO contained the correct 78XW that matches my engine, but it also contained a -590364 after 78XW or 78XW-590364. Does anyone know if the 590364 number should match the 6 digit number stamped on the engine block? in my case below the 78XW?

Much appreciated.

John


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## PontiacJim (Dec 29, 2012)

s27519 said:


> Received my build sheet from PHS. Notices that the "ENG or MOTOR UNIT NO contained the correct 78XW that matches my engine, but it also contained a -590364 after 78XW or 78XW-590364. Does anyone know if the 590364 number should match the 6 digit number stamped on the engine block? in my case below the 78XW?
> 
> Much appreciated.
> 
> John


VIN numbers were not stamped on the 1964 block. The 6 digit number is the Engine Sequence Number or Engine Unit Number (EUN) used at the factory. This is sometimes found on the PHS documents.

Another way to verify if original, is to look at the cast date code on the block near the distributor hole. If it is within about 6 weeks of the build date of the car, then good chance it is original. You can also break this down further and start checking head casting dates, and assorted part numbers like intake and exhaust manifolds, carb, distributor, etc..


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## s27519 (Sep 11, 2018)

*Just more questions*

Thank you PontiacJim for the details. So if I understand this correctly, can I assume that if my build sheet shows a motor unit number and it does not match the one stamped on my block that it is a non matching block for my car?

Appreciate the input.


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## PontiacJim (Dec 29, 2012)

s27519 said:


> Thank you PontiacJim for the details. So if I understand this correctly, can I assume that if my build sheet shows a motor unit number and it does not match the one stamped on my block that it is a non matching block for my car?
> 
> Appreciate the input.



Yes, that is correct. If the original engine is long gone, what some will do is find a replacement engine having the correct letter code as yours does which matches the build for your car. Not a perfect replacement of course, but it can satisfy many as opposed to slapping in a different 389 block from lets say a 1966 Bonneville and then adding the 1964 heads, intake, carb, exhaust manifolds, etc.. So it is as close to "original" as you could get without having the original engine. Some will even go as far as locating an engine having the casting date codes that would correspond with your car's build date.

So value wise, not a big loss in my book because it does have the correct letter code to match what your car was born with and as long as the rest of the engine components also match the engine as it was originally assembled. If I sold the car, I would point out that it was not the original engine, but has the correct 1964 block letter code and matching engine components as would have been original to the car. :thumbsup:


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## s27519 (Sep 11, 2018)

Thank you for your knowledge and response. I now can state what I actually have. BTW the 78XW engine has all the proper date codes part stamping that match such as the heads, intake and exhaust manifolds. Thanks again.


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## Shake-N-Bake (Jun 16, 2015)

s27519 said:


> Thank you for your knowledge and response. I now can state what I actually have. BTW the 78XW engine has all the proper date codes part stamping that match such as the heads, intake and exhaust manifolds. Thanks again.


Curious. What is the Engine Unit number on the PHS docs and what is the Engine Unit Number stamped on the block? How close are those two numbers?

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## s27519 (Sep 11, 2018)

*Reading a build sheet*

My number starts in the 552,000 range the builds sheet shows in the 590,000 range.

Any thoughts you can share is appreciated.

Thank you.


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## Shake-N-Bake (Jun 16, 2015)

s27519 said:


> My number starts in the 552,000 range the builds sheet shows in the 590,000 range.
> 
> Any thoughts you can share is appreciated.
> 
> Thank you.


No more thoughts other than what has been posted. Not original engine but a suitable replacement. Donor car preceded your car. All engines were assembled at the same place and then shipped to the various assembly plants around the country.

What I was hunting for is the possibility of a single digit variance.....in any of the decimal positions. If that were the case, then we could plot out casting dates and compare with other EUNs and determine if a typo or production error was in play. Stuff like that has happened, but of course not the normal situation.

Doesn't sound like we have anything like that happening here. Just a more common story of original engine required replacement at some point along the line. Based on the intended use of these cars..it is to be expected the engines would be one of the first things to fail and require attention.

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