#16 heads mystery numbers - Pontiac GTO Forum
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post #1 of 5 (permalink) Old 06-20-2019, 09:34 AM Thread Starter
 
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#16 heads mystery numbers

Hi,

Looking for help understanding what some numbers on my heads mean (if anything).

Here is what I know:
#16 casting number
F288 date code on both heads (June 28, 1968)
2.11/1.77 valves, 72cc chamber

What do these mean?:
Driver side casting#s: G DN. Passenger side casting#: 5 36
Below the "16" casting numbers on the center exhaust ports (on both heads) "6 2" is stamped into the flange. Have not seen this before. Any meaning?

Thanks!
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post #2 of 5 (permalink) Old 06-20-2019, 07:04 PM
 
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Sorry. Drawing a blank. I could help with the 16 and F288 codes but you have that covered already.
The other stuff is unknown to me.
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post #3 of 5 (permalink) Old 06-20-2019, 07:41 PM
 
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Originally Posted by ylwgto View Post
Hi,

Looking for help understanding what some numbers on my heads mean (if anything).

Here is what I know:
#16 casting number
F288 date code on both heads (June 28, 1968)
2.11/1.77 valves, 72cc chamber

What do these mean?:
Driver side casting#s: G DN. Passenger side casting#: 5 36
Below the "16" casting numbers on the center exhaust ports (on both heads) "6 2" is stamped into the flange. Have not seen this before. Any meaning?

Thanks!


The "62" looks fresh as compared to the rest of the casting. May simply be an ID stamping a machine shop or rebuilder added to keep track of the heads. Not anything I have ever seen as factory.

The "DN" should mean when they were cast, "Day" or "Night."

My Pontiac Performance book says the 3/6 is called the "sub-shift" and my educated guess would be the "5" represents the 5th week as some months have 5 weeks.

The "G" if large and located on the first port most likely represents "GM" as many of the heads do have the "GM" with the "M" below the "G" on the first exhaust port.

So that is my best educated guess on a few of the stampings.
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post #4 of 5 (permalink) Old 06-21-2019, 08:43 AM Thread Starter
 
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Great, thanks a lot. I suspected they weren’t factory stampings but you never know!
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post #5 of 5 (permalink) Old 06-21-2019, 11:46 AM
 
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I'll just take a "wild stab", or a "shot in the dark", as they say.

Since the '68 #16 heads were followed by #62 heads, on similar '69 engines, and since your #16 heads were cast late in the '68 model year, I suppose it MIGHT be possible that some of the left over #16 heads were used on '69 model year engines. Also, some #62 heads may have been used on some late '68 model engines. Lots of strange things happened on the production lines, that were not common practice. So, rather than hold up production, waiting on a set of #62 heads, they may have used some left over #16 heads on a few engines. Stranger things have happened on GM production lines.

EngineSpecs

OR, the stamped #62 may have absolutely nothing to do with the cast #16, or a the year model of the engine. The guy that added the stamped numbers may be one of the few, or maybe even the only guy who knows for sure.
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