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Forgetting (for a moment) about correctly-coded radiator caps, as they came from the factory...
You're all probably going to think I am nuts, but I e-mailed Stant to point out what I interpreted as a mistake I happened to notice in their radiator cap applications catalog. I had been trying to look up my '65 327, for which they listed 2 caps rated at 16 psi. I contacted them to let them know that midyears never had a 16 psi cap and that the applications as I knew them (and courtesy of L.I. Corvette Supply's catalog) were:
13 psi (1963 327 all, 1964-5 327 no AC, 396)
15 psi (1964-5 327 AC, 1966-7 327, 427)
They promptly responded as follows:
"...all radiator pressure caps are built in opening ranges. The range for the pressure cap for the 1965 Corvette is 14-18 psi. GM designates their cap in this range as a 15 psi cap. Ford and Chrysler designate it as a 16 psi cap. Stant has chosen to use the mid-point of the range as the opening designation for their cap, 16 psi."
I guess I can accept their response as to labeling convention in the case of 15 psi caps (although I always thought a rating corresponded to the psi a cap should hold BEFORE starting to open), but this doesn't address 13 psi caps.
So now I'll get to my question, which relates to GM Service Replacement caps...
We know that 327s went from 13 psi to 15 psi based on AC sometime in 1964 and all beginning with 1966. After that, once GM's supply of 13 psi caps were used up, did they begin issuing 15 psi Service Replacements (based on real world feedback and/or engineering rethink) for all 327 cars previously supplied with a 13 psi cap from the factory? Or did they continue to recommend and issue 13s for cars that came with 13s and 15s for cars that came with 15s? If the latter, what was different in terms of mechanical parts or timing, carb, etc., settings between, e.g., a 350 HP 327 (non AC) in '65 requiring a 13 psi cap and the '66 or '67 version requiring a 15 psi cap?
Any thoughts and/or recollections would be appreciated.
Louis
You're all probably going to think I am nuts, but I e-mailed Stant to point out what I interpreted as a mistake I happened to notice in their radiator cap applications catalog. I had been trying to look up my '65 327, for which they listed 2 caps rated at 16 psi. I contacted them to let them know that midyears never had a 16 psi cap and that the applications as I knew them (and courtesy of L.I. Corvette Supply's catalog) were:
13 psi (1963 327 all, 1964-5 327 no AC, 396)
15 psi (1964-5 327 AC, 1966-7 327, 427)
They promptly responded as follows:
"...all radiator pressure caps are built in opening ranges. The range for the pressure cap for the 1965 Corvette is 14-18 psi. GM designates their cap in this range as a 15 psi cap. Ford and Chrysler designate it as a 16 psi cap. Stant has chosen to use the mid-point of the range as the opening designation for their cap, 16 psi."
I guess I can accept their response as to labeling convention in the case of 15 psi caps (although I always thought a rating corresponded to the psi a cap should hold BEFORE starting to open), but this doesn't address 13 psi caps.
So now I'll get to my question, which relates to GM Service Replacement caps...
We know that 327s went from 13 psi to 15 psi based on AC sometime in 1964 and all beginning with 1966. After that, once GM's supply of 13 psi caps were used up, did they begin issuing 15 psi Service Replacements (based on real world feedback and/or engineering rethink) for all 327 cars previously supplied with a 13 psi cap from the factory? Or did they continue to recommend and issue 13s for cars that came with 13s and 15s for cars that came with 15s? If the latter, what was different in terms of mechanical parts or timing, carb, etc., settings between, e.g., a 350 HP 327 (non AC) in '65 requiring a 13 psi cap and the '66 or '67 version requiring a 15 psi cap?
Any thoughts and/or recollections would be appreciated.
Louis
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