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Keane165's 1970 LeMans

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Need block decoding help!

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hi jim hopefully frosty will see your ask and chime in :dancingpontiac:he is the go too man for numbers

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On 2/12/2021 at 6:16 PM, JimK said:

I have a pontiac motor that others have said belongs to a 1969 GTO Judge. Can anyone validate that with these numbers off of the block?




GM 543482

WT 686879

Hi Jim

I doubt that you have '69 GTO Judge motor but it is possible that you have a GTO motor.

Casting 9790071 was the standard casting number for all 400s in both 1968 and 1969. This included the 265HP version up to the 375 HP versions. So this engine could go in Tempest, Lemans, GTOs, Catalinas, Bonnevilles, etc.

Casting date E038 - this is when the block was cast at the Pontiac Foundry and the engine was built sometime affer that. E038 mean May 03, 1968. So theoretically this is a 1968-built motor. Having been built late in the model year, could this have been put into a '69 Judge? Perhaps.

WT 686879 - WT is a block code that designates which engine and transmission configuration this engine is and the six digits represent the last six digits of the vehicle's VIN number. WT was for 360 HP version in 1968 and 350 HP version in 1969 (so this is still a strong motor all day long). WT further tells us this engine was paired up with a manual transmission and 4-bbl carb in a Tempest body (Tempest/Lemans/GTO/Custom S could all have this engine/transmission). It also tells us this is a NOT WW or XP coded engine, which would be the famous Ram Air IV engine. XX would indicate a Ram Air III motor.

SInce the Judges were either RA III or RA IV motors, you do not appear to have a Judge motor. However, you do have a high horsepower A-body motor from a manual transmission car. Mostly likely this engine would have been in a '68 or '69 GTO or a very highly optioned Lemans.

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