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I need help identifying original 1965/1966 spark plug heat shields.I use to own a survivor 1965 396.As i remember them they had a difinite seam running down the center of the shield.I just saw a set, and the owner of the car(1966 427/425)let me look at his original shields.Upon viewing, off the car, his shields had what can best be described as a faint straight line scratch at about the 8 o'clock position.I recall the seam being in the middle and much more defined.Can anyone tell me how to identify an original? Thanks, for any help.
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Re: 1965/1966 big block spark plug heat shields
Louis,
It's possible that the originals from your 65 396 car are different than those found on a 66 427 car. There were a few changes in the part some time around late 65 or early 66 and the part number changed for the newly released replacement. One of the changes I remember was the fact that the small 1/4" hole used to mount the shield to the cyl head was changed to a slot. I also vaguely remember a change in the way the part was formed and that would have resulted in a change in the seam. Maybe someone has one of each style and can better describe the small changes. I don't have info on the original 65 part number but hopefully Joe Lucia would be able to help with that.
Michael -
Re: 1965/1966 big block spark plug heat shields
Louis,
It's possible that the originals from your 65 396 car are different than those found on a 66 427 car. There were a few changes in the part some time around late 65 or early 66 and the part number changed for the newly released replacement. One of the changes I remember was the fact that the small 1/4" hole used to mount the shield to the cyl head was changed to a slot. I also vaguely remember a change in the way the part was formed and that would have resulted in a change in the seam. Maybe someone has one of each style and can better describe the small changes. I don't have info on the original 65 part number but hopefully Joe Lucia would be able to help with that.
MichaelComment
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Re: 1965/1966 big block spark plug heat shields
Michael and Louis-----
The spark plug shields for 1965 L-78 were supposed to be GM #3868828. However, if these were used, at all, they were used only on very early L-78s (which, of course, were introduced mid model year). Most, if not all, L-78s used the GM #3871266 shield, the same as used for 1966 big blocks.
The 3868828 had the slot for the retaining bolt; the 3871266 had a complete hole for the retaining bolt. There were a few other configuration differences between the 2 shields. The slot versus hole is the easiest way to tell the difference. Also, the 3868828 was 2-1/2" long whereas the 3871266 was 3" long.
The GM #3868828 shields were NEVER available in SERVICE. If they were manufactured, at all, they were used for PRODUCTION only. The 3871266 were used in PRODUCTION and available in SERVICE (until 1977).In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
Michael and Louis-----
The spark plug shields for 1965 L-78 were supposed to be GM #3868828. However, if these were used, at all, they were used only on very early L-78s (which, of course, were introduced mid model year). Most, if not all, L-78s used the GM #3871266 shield, the same as used for 1966 big blocks.
The 3868828 had the slot for the retaining bolt; the 3871266 had a complete hole for the retaining bolt. There were a few other configuration differences between the 2 shields. The slot versus hole is the easiest way to tell the difference. Also, the 3868828 was 2-1/2" long whereas the 3871266 was 3" long.
The GM #3868828 shields were NEVER available in SERVICE. If they were manufactured, at all, they were used for PRODUCTION only. The 3871266 were used in PRODUCTION and available in SERVICE (until 1977).In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
Joe the original tubes from 65 # 16120 are a full 3" long with slots . The line is the tube weld line and is not in the same position on each tube. The tubes were dull silver cad plated.....BillComment
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Re: 1965/1966 big block spark plug heat shields
Joe the original tubes from 65 # 16120 are a full 3" long with slots . The line is the tube weld line and is not in the same position on each tube. The tubes were dull silver cad plated.....BillComment
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Re: 1965/1966 big block spark plug heat shields
Bill-----
What is the configuration of the rear of the "cutout" section on the front portion of the shield? Is it squared off or radiused?
The GM specs for both of these shields called for zinc plating. No optional spec for cadmium was specified.In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
Bill-----
What is the configuration of the rear of the "cutout" section on the front portion of the shield? Is it squared off or radiused?
The GM specs for both of these shields called for zinc plating. No optional spec for cadmium was specified.In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
Joe, FWIW, I just removed one from my 66 and it's radiused. (Nov 65 build)Comment
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Re: 1965/1966 big block spark plug heat shields
Joe, FWIW, I just removed one from my 66 and it's radiused. (Nov 65 build)Comment
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Re: 1965/1966 big block spark plug heat shields
Michael------
Apparently, these things were made up a variety of ways. The 1965 GM #3868828 are supposed to be 2-1/2" long with a slot in the bracket and a radiused end for the rear of the "cut out" section.
The late 1965 and 1966 GM #3871266 are supposed to be 3" long with a hole in the attaching bracket and a "squared off" end at the rear of the "cut out" section.
Maybe the supplier couldn't get it right.In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
Michael------
Apparently, these things were made up a variety of ways. The 1965 GM #3868828 are supposed to be 2-1/2" long with a slot in the bracket and a radiused end for the rear of the "cut out" section.
The late 1965 and 1966 GM #3871266 are supposed to be 3" long with a hole in the attaching bracket and a "squared off" end at the rear of the "cut out" section.
Maybe the supplier couldn't get it right.In Appreciation of John HinckleyComment
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Re: 1965/1966 big block spark plug heat shields
I believe you are correct Joe. The one I just removed has the radius but also has the hole instead of slot. I just tried to post a pic but my hosting service failed.Comment
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Re: 1965/1966 big block spark plug heat shields
I believe you are correct Joe. The one I just removed has the radius but also has the hole instead of slot. I just tried to post a pic but my hosting service failed.Comment
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