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Need help decoding big block.......

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Old Sep 22, 2010 | 10:34 AM
  #1  
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Default Need help decoding big block.......

Heads are marked GM4T, pass side-3931063
drivers side-3964280. other no. J7\8

Block is GMT7, no 3963512 on rear surface,
clock at 5 o'clock dot on pass side

654
512 on rear face

PASS
1 PERF on front face

Serial pretty obscured, I can make out C?1673?4

Thanks for anything you can do. K

Last edited by Kerrmudgeon; Sep 22, 2010 at 10:38 AM.
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Old Sep 22, 2010 | 12:16 PM
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Originally Posted by kerrmudgeon
Heads are marked GM4T, pass side-3931063
drivers side-3964280. other no. J7\8

Block is GMT7, no 3963512 on rear surface,
clock at 5 o'clock dot on pass side

654
512 on rear face

PASS
1 PERF on front face

Serial pretty obscured, I can make out C?1673?4

Thanks for anything you can do. K
That block was used from '69-'71 for 427 and 454 applications - heads are oval-port 390hp style, and one has been replaced (driver's side head is 4290, not 4280). Block casting date was on the pass. side just forward of the starter in '69, and moved to the rear flange in '70.

The partial VIN starting with a "C" says it's out of a Chevy pickup.
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Old Sep 22, 2010 | 12:23 PM
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Originally Posted by kerrmudgeon
Heads are marked GM4T, pass side-3931063
drivers side-3964280. other no. J7\8

Block is GMT7, no 3963512 on rear surface,
clock at 5 o'clock dot on pass side

654
512 on rear face

PASS
1 PERF on front face

Serial pretty obscured, I can make out C?1673?4

Thanks for anything you can do. K

Could the serial number start with CE on the block which would then indicate it is a warranty motor.

Mike
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Old Sep 22, 2010 | 01:24 PM
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Originally Posted by mhanley
Could the serial number start with CE on the block which would then indicate it is a warranty motor.

Mike
Good catch! If it reads "CE 1673?4", that's the correct format for a Tonawanda "CE" big-block assembled in 1971.
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Old Sep 22, 2010 | 01:37 PM
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You guys are great, thanks very much. So it looks like a warranty/replacement motor was installed in 1971. The car is supposed to be a 68 427 390hp 4-sp car, but I just got the vin, here it is, 194678S406634. Does that make sense? What else does it tell you? Thanks again, K
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Old Sep 22, 2010 | 01:55 PM
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Originally Posted by kerrmudgeon
You guys are great, thanks very much. So it looks like a warranty/replacement motor was installed in 1971. The car is supposed to be a 68 427 390hp 4-sp car, but I just got the vin, here it is, 194678S406634. Does that make sense? What else does it tell you? Thanks again, K
Sez it's a '68 convertible built on 12/13/67; that's all you can get from the VIN; there was no engine info in the VIN until 1972.
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Old Sep 22, 2010 | 02:29 PM
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Thanks again John.
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Old Sep 22, 2010 | 07:57 PM
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Originally Posted by JohnZ
Sez it's a '68 convertible built on 12/13/67; that's all you can get from the VIN; there was no engine info in the VIN until 1972.
better than google.com....thank goodness we have people like John on here ....
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Old Sep 23, 2010 | 09:38 AM
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Originally Posted by MidYearRoadster
better than google.com....thank goodness we have people like John on here ....
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