Author Topic: Cyl Head 3947041  (Read 2346 times)

jdv69z

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Cyl Head 3947041
« on: January 03, 2013, 02:38:00 PM »
Looking at a head #3947041 with casting date of C21 9; Has 5/8" tapered seat plugs. Is this a 69 produced head for 1970 model year? I thought 69's have the 13/16" plugs with the washers. Or could it have been changed?
 
Jimmy V.
Jimmy V.

1968RSZ28

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Re: Cyl Head 3947041
« Reply #1 on: January 03, 2013, 07:44:09 PM »

z28z11

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Re: Cyl Head 3947041
« Reply #2 on: January 04, 2013, 12:34:46 AM »
Jimmy,

Colvin references this in his 65-69 Chevrolet by the Numbers, and in the 70- up book also (I'll paraphrase) - "65-69 cars came with "N" series heads, or flat gasket spark plug seats. All 1970 and later model year cars were produced with a "peanut" or tapered spark plug seat. It is possible, due to late model releases in 1970, that 2 cylinder heads could have close or matching casting dates and be tapped for different type spark plugs."

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

KevinW

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Re: Cyl Head 3947041
« Reply #3 on: January 04, 2013, 11:32:43 AM »
The 041 head was used primarily on SS350 Camaros.  The 69 Models were made until Nov of 69.  So this head was made March 21 of 69, well within the model year. Maybe it was modified?

jdv69z

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Re: Cyl Head 3947041
« Reply #4 on: January 04, 2013, 01:48:05 PM »
What I thought. This head has inserts for unleaded fuel so maybe it was modified for tapered seat plugs. But I don't know why someone would do that. Either that or it wasn't used until 1970 production. But that seems hard to believe as well. There is another head that came with this one. I'll have to check the date on that one.

Jimmy V.

jdv69z

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Re: Cyl Head 3947041
« Reply #5 on: January 04, 2013, 01:57:23 PM »
Other head is same date

Jimmy V.

KevinW

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Re: Cyl Head 3947041
« Reply #6 on: January 04, 2013, 02:46:49 PM »
I have a set of D69 041 heads in the basement, I have to take a quick look at the plug holes :)

KevinW

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Re: Cyl Head 3947041
« Reply #7 on: January 04, 2013, 02:48:27 PM »
Oh yea, I am running a set of E69 heads on my SS350 and they have the regular flat plugs.

KevinW

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Re: Cyl Head 3947041
« Reply #8 on: January 05, 2013, 03:31:08 AM »
Yes, the D69 have the same flat plug holes.

tmodel66

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Re: Cyl Head 3947041
« Reply #9 on: January 05, 2013, 03:48:04 AM »
What I thought. This head has inserts for unleaded fuel so maybe it was modified for tapered seat plugs. But I don't know why someone would do that. Either that or it wasn't used until 1970 production. But that seems hard to believe as well. There is another head that came with this one. I'll have to check the date on that one.

Jimmy V.

Jimmy it's been a while. Refresh my memory on the unleaded fuel inserts. I can't get the picture in my mind.
Daniel  
'69 SS 350/4 speed  Fathom Green--POP

JohnZ

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Re: Cyl Head 3947041
« Reply #10 on: January 05, 2013, 04:08:25 PM »
What I thought. This head has inserts for unleaded fuel so maybe it was modified for tapered seat plugs. But I don't know why someone would do that. Either that or it wasn't used until 1970 production. But that seems hard to believe as well. There is another head that came with this one. I'll have to check the date on that one.

Jimmy V.

Jimmy it's been a while. Refresh my memory on the unleaded fuel inserts. I can't get the picture in my mind.

If it has hardened seat inserts, they were done in a machine shop somewhere - Chevrolet never used them. Unleaded gas wasn't mandated until 1975, and Chevrolet responded with electrically induction-hardened seat areas in the cast iron.
'69 Z/28
Fathom Green
CRG