pontiac 400 small block - Pontiac GTO Forum
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post #1 of 17 (permalink) Old 08-23-2013, 08:26 PM Thread Starter
 
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pontiac 400 small block

Hello there! I am new! My name is Cristian and I am from Orange County, CA!


I bought my 71 nova about 5 years. When I bought it, the seller told me the motor was a Pontiac 400 small block out of a GTO. I knew very little about muscle cars back then and I thought I was buying it for a good deal.

Now im 23 years old and wanting to rebuild the motor yet IDK what I exactly have. I was looking around the block and I saw on the passenger block above headers had some numbers. I also looked under the distributor cap. After doing my research I understood that the 6x heads were never in a GTO to begin with because they started in 77-79. I uploaded two images. Where else should I look on the motor?


The numbers by the passenger side above headers were C306 Then over the last spark plug it was D then N. Also vertically as you can see it is GM3 and horizontally 6X.

Under the distributor cap as you can tell by the picture the numbers are A038.

I googled these numbers and have no luck. Can anyone steer me in the right direction on finding out what I exactly have? Thank you. I really want to build this motor to 300 ponies or more!
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post #2 of 17 (permalink) Old 08-23-2013, 08:35 PM
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Welcome to the forums!
Check this site...
Pontiac Power
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post #3 of 17 (permalink) Old 08-23-2013, 08:45 PM Thread Starter
 
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Appreciate it ill go under my car and look.
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post #4 of 17 (permalink) Old 08-23-2013, 09:06 PM
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The heads are '76. C306 - March 30th, '76
Block is a '68 or '78 - A038 January 3rd '68 or '78. Block casting number would help determine the year...

D and N is the shift - Days/Nights



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post #5 of 17 (permalink) Old 08-23-2013, 09:25 PM Thread Starter
 
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Sweet thanks for the info.

On the driver side of the block I saw 6x and also A068.... Vertically it said G M 7. After the A068 to the right it said D and N.

On each head the stamped ID is 8.
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post #6 of 17 (permalink) Old 08-23-2013, 09:26 PM Thread Starter
 
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Where is the block casting number ?
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post #7 of 17 (permalink) Old 08-23-2013, 09:33 PM Thread Starter
 
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9790071 Wow there it is! I found it!
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post #8 of 17 (permalink) Old 08-23-2013, 09:36 PM Thread Starter
 
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So I have a 1968 block with one side 76 head and the other 78?

A068 was driver side head.

C306 was passenger side head.

Weird....
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post #9 of 17 (permalink) Old 08-23-2013, 09:45 PM
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I would double check the last digit on those heads. 8s can look like 6s and 6s can look like 8s.....



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post #10 of 17 (permalink) Old 08-23-2013, 09:47 PM Thread Starter
 
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I cleaned them up well it is clearly visible that driver side is 8 and passenger side is 6.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO General Discussion

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