# Decoding a 400 small block



## Shaffersphac (Oct 27, 2014)

I purchased a 68 gto it came with a 400 small block sitting in the trunk don't ask why it was in the trunk lol, so I'm wondering how to tell if it is the numbers matching motor for the car ive got some number of the motor 9790071 and gm 10 on the side of the motor let me know if I need to find more numbers thanks


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## eeyore (Oct 23, 2014)

Pontiac engines are externally all the same size except for the 301. Is it a chevy motor in the trunk?
Wallace Racing's Pontiac Engine Search


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## ibarbuckle (Feb 24, 2014)

9790071 is a '68/'69 400ci casting. As mentioned, Pontiac's are just V8s, no big/small block nonsense.


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## geeteeohguy (Feb 2, 2008)

Agreed. No Pontiacs are small blocks, not with their size and weight!! Closer to a big block than anything, but actually a 'mid' block.


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## 05GTO (Oct 6, 2004)

9790071 was used for 68 and 69, if the block has an 8 bolt water pump it is 68 and an 11 bolt WP was used for 69, also there is a date code on the machined pad next to the distributor pad, that date should be just prior to the car's build date.

I agree with geeteeohguy a Pontiac block in my opinion compared to Chevy's big and small would be a medium block.

JMHO


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## Shaffersphac (Oct 27, 2014)

Sorry haven't checked for a few days I'll run a stakes look Arvin number thanks for the picture


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## Shaffersphac (Oct 27, 2014)

28p229042 motor vin

242378r156215 car vin

Apparently not matching thanks for the help


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