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Discussion Starter · #1 ·
I just found a set pf heads casting #3748770 date code K 6 57 & K 15 57. They have the traditional PP symbol on one end, but the other end has bosses cast into it like later 350 heads. The bosses are not drilled & tapped. Yes, they have staggered valve cover holes. Anyone ever seen these heads before.
 

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I just found a set pf heads casting #3748770 date code K 6 57 & K 15 57. They have the traditional PP symbol on one end, but the other end has bosses cast into it like later 350 heads. The bosses are not drilled & tapped. Yes, they have staggered valve cover holes. Anyone ever seen these heads before.
With those dates they are for a 58. I have seen some 58 & 59 P/P heads with those bosses usually on Vette applications.

-Bruce
 

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Discussion Starter · #3 ·
Since the bosses are not taped what were they for, possibly an air pump for an Impala with air ride if so equipped.
 

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Since the bosses are not taped what were they for, possibly an air pump for an Impala with air ride if so equipped.
Casting #3748770 fit 1958-62 283 with a 1.72 intake valve and a 1.5 exhaust valve. Your cast date indicates an early 58 model year production. They were used on 58 base engines as well as some optional engines in both passenger cars as well as Corvettes. There are some differences in the machining process between the two though. The passenger cars had a somewhat rough cast on the end without the bosses where the vette application had a machined surface on the raised portion of the typical P/P pattern. If you post or send me some pics of the ends I can help further ID these.

-Bruce
 

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What are bosses?? Peter
Raised areas on the ends of the heads.....I thought Chevy didn't start doing this on cars until 68 or 69, when they drilled holes for the accessories.

New one on me for sure!
 

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Discussion Starter · #10 · (Edited)
Casting #3748770 fit 1958-62 283 with a 1.72 intake valve and a 1.5 exhaust valve. Your cast date indicates an early 58 model year production. They were used on 58 base engines as well as some optional engines in both passenger cars as well as Corvettes. There are some differences in the machining process between the two though. The passenger cars had a somewhat rough cast on the end without the bosses where the vette application had a machined surface on the raised portion of the typical P/P pattern. If you post or send me some pics of the ends I can help further ID these.

-Bruce
I compared the end of the head with the bosses to that on a mid 70s 882 casting and the quality of machine work is equal .

I would have agreed with eariler post that Chevy did not do this until 68 or 69 until this week.
 

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I compared the end of the head with the bosses to that on a mid 70s 882 casting and the quality of machine work is equal .

I would have agreed with eariler post that Chevy did not do this until 68 or 69 until this week.
Any pictures yet? These may or may not be for Corvette depending on what the end casting looks like. :dontknow: There is a big difference in value between the two.

-Bruce
 

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Discussion Starter · #12 ·
The heads are at the machine shop at this time and I may return them to the current owner as they have 62 CC combustion chambers. I need a pair with 58 CC. I can tell you the bosses are machined smooth, sorry I dont own a camera.
 
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