I want to know if the oval port "206" cylinder heads could have possibly appeared on the very early '66 427/390 hp engine. Raymond
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anything is possible
It all depends upon the date codes for the heads and engine. If the heads for instance have a July 65 date code and the block has a July or August code, that would certainly be plausible, but if the heads have a February 65 date and the block is July or later, that would be less likely as those heads were used on ALL the oval port engines including the pass car 396, so there was quite a turnover in the castings. I would be surprised to find a "date code matched pair" that somehow managed to sit together at Tonawanda in a back corner for several months waiting to be put on a later date block - less likely, but may have happened.
On the other hand, I don't think there are a lot of external differences between the 1965 and 1966 model oval port head. As far as I remember, there were a few 1/8" holes on the intake manifold face of the 1965 heads, and the cooling holes for the spark plugs were different (I think only one instead of two at each plug?). So if you left them on the engine, would anyone be able to tell?
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Re: anything is possible
That's exactly what I'm talking about. Late dated "206" heads could have appeared on very early 390 hp Corvettes or pass. cars for that matter. I have a pair of those heads dated mid-July of '65. The next question would be when the "702" heads came into production. RaymondComment
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what dates are the block casting and engine? *NM*
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Re: what dates are the block casting and engine?
Mark, There is no block that I can refer to. I did a minor BB survey many years ago & checked my info on early '66 "IL" & "IM" blocks. Alas, I lost some data & I had scant info & could not come up w/ any 206 heads. When I was doing the survey I had no idea that the cylinder heads could be other than "702's"Comment
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