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learned something from tdb members--the lack of a cast boss just below the two lower valve cover attaching bolts on the 461x heads and the presence of such projection in the casting on the non-461x sbc chevy heads. BTW, when going thru my bunch of 461x heads, i found another with the most recent casting date in my heads--its a F 11 2 cast date. mike
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Re: 461-x heads
Can this cast boss be viewed with the valve cover installed or does it have to be removed? Can you post a photo?
Duke -
Re: 461-x heads
Can this cast boss be viewed with the valve cover installed or does it have to be removed? Can you post a photo?
DukeComment
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Re: 461-x heads
you can feel for it. the 461X is flat horizontally right below the head-valve cover interphase. on the later sbc heads, the protrusion is about 3/8" wide and protrudes about 3/16 . the protrusions/bosses are right where the head is drilled and tapped for the valve cover fastner. its presence or absence is real easy to discern by running your finger along the head, horizontrally, just under the valve cover. mikeComment
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Re: 461-x heads
you can feel for it. the 461X is flat horizontally right below the head-valve cover interphase. on the later sbc heads, the protrusion is about 3/8" wide and protrudes about 3/16 . the protrusions/bosses are right where the head is drilled and tapped for the valve cover fastner. its presence or absence is real easy to discern by running your finger along the head, horizontrally, just under the valve cover. mikeComment
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Re: 461-x heads
Thanks! Now I understand. I have a spare set of 461X and the casting below the valve cover rail on the exhaust side is dead flat, front to back.
And I understand the 461 non-X or later "double hump" castings will have a slight "bulge" at the valve cover hold down bolt bores on this surface.
Is this an absolute, positive, sure-fire way to ID 461X castings from all later "double humps" including 461 non-X or are there any exceptions?
DukeComment
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Re: 461-x heads
Thanks! Now I understand. I have a spare set of 461X and the casting below the valve cover rail on the exhaust side is dead flat, front to back.
And I understand the 461 non-X or later "double hump" castings will have a slight "bulge" at the valve cover hold down bolt bores on this surface.
Is this an absolute, positive, sure-fire way to ID 461X castings from all later "double humps" including 461 non-X or are there any exceptions?
DukeComment
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Re: 461-x heads
not aware of any exceptions but i only checked my 7 sbc midyears with camel humps(63 thru 65 FI's) and they have the protrusions.all my cars with 461X have the flat non=protrusion head horizontal surfaces. perhaps more will chime in on this issue. regards, mike PS: the 250hp 283 is getting close to needing the cam you've selected for it.Comment
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Re: 461-x heads
not aware of any exceptions but i only checked my 7 sbc midyears with camel humps(63 thru 65 FI's) and they have the protrusions.all my cars with 461X have the flat non=protrusion head horizontal surfaces. perhaps more will chime in on this issue. regards, mike PS: the 250hp 283 is getting close to needing the cam you've selected for it.Comment
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Is this the bulge...
you are talking about? This one protrudes about 1/16".
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Is this the bulge...
you are talking about? This one protrudes about 1/16".
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Is That "C 17 5"?
That looks like the "flat". The protrusion, which shows up on a pair of '63 heads that I have, is much more pronounced. As was stated earlier, they protrude about 3/16", and their radii are also about 3/16", so just about a full semicircle protrudes.
My April 1965 heads look like yours ("flat").Comment
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Is That "C 17 5"?
That looks like the "flat". The protrusion, which shows up on a pair of '63 heads that I have, is much more pronounced. As was stated earlier, they protrude about 3/16", and their radii are also about 3/16", so just about a full semicircle protrudes.
My April 1965 heads look like yours ("flat").Comment
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Joe, it is C 17 6 *NM*
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Joe, it is C 17 6 *NM*
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