Help for date code on BBC heads - Team Camaro Tech
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post #1 of 13 (permalink) Old Feb 8th, 10, 11:44 AM Thread Starter
mike
 
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Help for date code on BBC heads

Hi, I am looking for some help with the date code on a set of heads I have. I have searched but have not found the exact answer I am looking for. The heads are a set of 3964291 closed chambered square port heads with a date code of L1, and this is where it gets cofusing, a small blob or what looks like maybe a symbol and either an 8 or could be a 0 if they put a line through the middle of the 0 like some do. If these are 1970 heads would there be a 70 or just a 0. If they are 68 heads could they be original to my late 68 camaro 396 car that I bought in 1982.
Sorry if I have duplicated this question but I could not find an answer during my search.

thanks
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post #2 of 13 (permalink) Old Feb 8th, 10, 12:24 PM
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Re: help for date code on bbc heads

If they were 1970 there would be 70. I would say either L 1 8 or L 1 9
Nov. 68 or Nov. 69. I think they remove I from calender dating , so 11th month 109 cc heads.
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post #3 of 13 (permalink) Old Feb 8th, 10, 12:50 PM
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Re: help for date code on bbc heads

Quote:
Originally Posted by 02dynamike View Post
Hi, I am looking for some help with the date code on a set of heads I have. I have searched but have not found the exact answer I am looking for. The heads are a set of 3964291 closed chambered square port heads with a date code of L1, and this is where it gets cofusing, a small blob or what looks like maybe a symbol and either an 8 or could be a 0 if they put a line through the middle of the 0 like some do. If these are 1970 heads would there be a 70 or just a 0. If they are 68 heads could they be original to my late 68 camaro 396 car that I bought in 1982.
Sorry if I have duplicated this question but I could not find an answer during my search.

thanks
Are both heads the same date?

L casting date month is December. See this link.
http://www.camaros.org/numbers.shtml...ernalDateCodes

The 291 heads were not used on 1968 vehicles. If the date code on yours is December 68 - they would have been on a 1969 model year vehicle. If December 69, then on a 1970 model year vehicle.

68 Camaro SS 396 - 468 BBC now, Air Gap Intake, 781 heads, M21, 12 bolt. / 67 Chevelle SS 396.
Looking for 68 Camaro with body number NOR 181016
CRG - www.camaros.org
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post #4 of 13 (permalink) Old Feb 8th, 10, 01:56 PM
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Jay
 
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Re: help for date code on bbc heads

I have a set of those heads from a july 67, 68 camaro mx coded block.. I will check em and see if they are similar...
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post #5 of 13 (permalink) Old Feb 8th, 10, 02:52 PM
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Vince
 
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Re: help for date code on bbc heads

I agree that the 3964291 heads were from the 70 model year, great pair of heads.

1967 327 4spd convertible 119K
1968 RS Z/28 68K
1969 307/350 57K----sold
1969 Z/28 X33
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post #6 of 13 (permalink) Old Feb 8th, 10, 04:03 PM
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Re: help for date code on bbc heads

Quote:
Originally Posted by red67L78 View Post
If they were 1970 there would be 70. I would say either L 1 8 or L 1 9
Nov. 68 or Nov. 69. I think they remove I from calender dating , so 11th month 109 cc heads.
Don't think so. On 70 cast heads, it would read L 1 0. However, that is either L 1 8 or L 1 9, as GM did not put a line through the 0. Sometimes very hard to distiguish 8 from 9 on those casting dates.

Here is a 186 head cast Feb 4, 1970 (B 4 0)
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post #7 of 13 (permalink) Old Feb 8th, 10, 04:11 PM
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Vince
 
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Re: help for date code on bbc heads

Dec 1 of 69 would be for the 70 model year.

1967 327 4spd convertible 119K
1968 RS Z/28 68K
1969 307/350 57K----sold
1969 Z/28 X33
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post #8 of 13 (permalink) Old Feb 9th, 10, 09:27 PM Thread Starter
mike
 
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Re: Help for date code on BBC heads

Thanks to everyone for the replys the info was very helpfull especially for the info regarding the month of casting. I have taken a better look at the second head and it has a little better year cast into it with the same month and day. L 1 8
Now that I have a better idea about what these heads are and when they were made I will be able to decide if I will reinstall these back on the 427 in the car or find a more suitible head for my combination.

Thanks again

mike
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post #9 of 13 (permalink) Old Feb 10th, 10, 08:29 AM
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Robert
 
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Re: Help for date code on BBC heads

Those heads were used 69 and 70. One thing you guys missed is the spark plug hole size. ALL 1970 model year heads used the small tapered seat spark plug and all 69 models used the larger flat washer type speark plug. the spark plug hole will tell you which year they are.


The pic looks like L 1 1969 to me, check spark plug holes for tapered seat machining

Last edited by 1stGenLvr; Feb 10th, 10 at 09:46 AM.
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post #10 of 13 (permalink) Old Feb 10th, 10, 09:06 AM
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Thumbs up Re: Help for date code on BBC heads

Quote:
Originally Posted by 1stGenLvr View Post
... ALL 1970 model year heads used the small tapered seat spark plug and all 69 models used the larger flat washer type speark plug. the spark plug hole will tell you which year they are.
^^^

Looks like Dec. 1 1969 to me
Cast on second shift ...

1968 Convertible
Some trucks
Other V8 things - some of which float
Other V6 things - none of which float
Oh yeah, and 1 "Straight-Six" ...

If a man says something in the garage - and his wife can't hear him - is he still wrong !!!
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post #11 of 13 (permalink) Old Feb 11th, 10, 05:27 AM
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Re: Help for date code on BBC heads

The date would be L 1 9.
The 840 casting heads were phased from casting production in May of 1969.
The 291 casting heads did not begin production unitl June of 1969.
The first production runs of 291 heads have washered plugs.
Late 69 engines, from July to October, have been found with mixed casting heads one #840 and one #291.
Hope this helps.
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post #12 of 13 (permalink) Old Feb 11th, 10, 05:49 PM Thread Starter
mike
 
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Re: Help for date code on BBC heads

Wow, My first post and I have already made a mistake. Really thought that 9 looked like an 8 but after looking at it closer and comparing it to the 9 in the 3964291 it must be. Also the heads do have the tapered plugs.

Thanks again.

Also one other question, just out of curiosity how do you know they were cast on the second shift? Is it the GM2T
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post #13 of 13 (permalink) Old Feb 12th, 10, 10:15 AM
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Wink Re: Help for date code on BBC heads


The shift is indicated by the shape of the screw(s) used to anchor the casting date plate
(or on the 'clock' used on some other parts)
Most GM casting plants operated in two 10-hour shifts.
'Flat' is 1st shift
'Round' is 2nd

1968 Convertible
Some trucks
Other V8 things - some of which float
Other V6 things - none of which float
Oh yeah, and 1 "Straight-Six" ...

If a man says something in the garage - and his wife can't hear him - is he still wrong !!!
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