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Casting number and date code don't jive

2K views 7 replies 4 participants last post by  TroyBoy 
#1 ·
I received a pair of big valve double hump heads for free from my old neighbor (what a guy!). Of course they look pretty rough, and are going to need some money sacrificed at the machine shop. The casting numbers are the same on each head, but the date codes are different.

Casting: 3917291
Valves: 2.02/1.50
Chamber: 64cc

Date codes:
C26 (C=March, 2=second day of month, 6=1966)...this seems to line up exactly with a 327 or 350ci engine.

D30 (D=April, 3=third day of month, 0=1960 or 1970)
The big valves in this casting number were only made from 1964 - 1968. So where does the "0" digit fit into a year?

All the other visual cues match on both heads:
-Valve cover bolt holes are on the edges and are symmetrical top to bottom
-Drilled and tapped temp sending unit boss
-No accessory holes
-Pressed in studs
-No pushrod guide plates
-Heavy casting style
-Exhaust mounting holes are the early two hole style with no third hole or left over boss for the 3rd hole.
-Spark plug seats I believe are the flat style...which would make it pre-1971. Does anyone have a good picture or link to positively ID tapered vs flat style?

Can anyone help me with the D30 casting date?
Thanks!
 
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#5 ·
delawarebill said:
the zero is a good question.. don't have the answer either.. i'm try'n to do my motor but the numbers don't make sence.
G747 ??? well to me anyways...
Well that is odd isn't it. I assume these are standard SBC heads?

G: July
7: 7th
47: 1947

But the small block didn't appear until 1955. Do you have the casting numbers?
 
#6 ·
You sure the c/n isn't 3912291? These were used through '70.

Even if the c/n IS 3917291, these heads were used through '69. I suppose it could be possible for them to have been cast into the '70 model year.

Info above from HERE, a really good site for casting numbers. There are still a few discrepancies, but less than many lists and there are numbers here that aren't found in other lists. ;)
 
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