C3 Engine/Head I.D
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 5,159
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From: Indiana
C3 Engine/Head I.D
In my fact-finding re: the '69 vert I'm playing with, I've already figured out that the HY motor is a 350/300 MT. Now, the heads have casting numbers 3978487 with H191 under the first string of numbers. Are these the correct heads for this block?
Thanks also to Bluevetteman for answering my vacuum question earlier. Now I'm trying to find a way to seal up those fittings at the push/pull *****. They both leak a little.
Thanks all!
Randy
Thanks also to Bluevetteman for answering my vacuum question earlier. Now I'm trying to find a way to seal up those fittings at the push/pull *****. They both leak a little.
Thanks all!
Randy
Safety Car
Joined: Dec 1999
Posts: 3,605
Likes: 839
From: PA
Re: C3 Engine/Head I.D
In my fact-finding re: the '69 vert I'm playing with, I've already figured out that the HY motor is a 350/300 MT. Now, the heads have casting numbers 3978487 with H191 under the first string of numbers. Are these the correct heads for this block?
The heads used on the ZQ3 (350/300) engine in 1969 typically had a 3927186 casting number, although I'll mention that casting number 3947041 is also listed as correct in my reference material.
The 3978487 casting was used initially in Corvette applications during the 1971 model year. This casting had a combustion chamber with greater volume than the earlier castings which effectively reduced the compression ratio. The date code on your cylinder heads, H 19 1, would indicate a casting date of August 19, 1971 which would be a reasonable date for an early production 1972 small block Corvette (and probably other Chevrolet products as well).
To answer your question, no, these are not the correct heads for a 1969 "HY" code engine although locating a set of correct 186s shouldn't be too hard if you wish to replace the current heads with a more correct pair.
Regards,
