[C2] Gear ratio with A/C
05-18-2017, 12:10 AM
#1
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Gear ratio with A/C
I have a question that I need some help with. No amount of searching has turned up the answer I'm looking for, so here goes.
I can find listings of rear gear ratios available for 1967, but none specify with or without A/C. My experience with other GM performance cars of that era is that many were often limited. The car in question is a 4 speed 427/400 with A/C. I need to know what gears were offered with that combination, not how to identify what I currently have.
Any facts or link to facts would be greatly appreciated.
As always, thank you.
I can find listings of rear gear ratios available for 1967, but none specify with or without A/C. My experience with other GM performance cars of that era is that many were often limited. The car in question is a 4 speed 427/400 with A/C. I need to know what gears were offered with that combination, not how to identify what I currently have.
Any facts or link to facts would be greatly appreciated.
As always, thank you.
05-18-2017, 12:34 AM
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C1 of Year Finalist (performance mods) 2019
I don't think there was anything limiting what you could have.
The way that Chevy limited potential damage was by cam availability. After A/C was available in a high lift cam in 64-65 they ended it. My guess would be from warranty claims for A/C compressors being damaged from hi RPMs but that is just an educated guess from spend many years in the new car business.
The way that Chevy limited potential damage was by cam availability. After A/C was available in a high lift cam in 64-65 they ended it. My guess would be from warranty claims for A/C compressors being damaged from hi RPMs but that is just an educated guess from spend many years in the new car business.
05-18-2017, 10:33 AM
#3
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The same ratios were available with or without air conditioning. Specifying AC did not require a different/special rear gear.
Larry
Larry
05-18-2017, 10:40 AM
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Interesting. With GM mid-sized musclecars of that era, AC cars were limited to about a 3.36 gear at the lowest. The preferred ratio by the manufacturer was about a 2.93-3.08, though. Anything 3.55-up, no AC. Strange you could get a Corvette with AC and 4.11 gears with a 427...talk about a time bomb on the freeway on a hot day!
05-18-2017, 10:57 AM
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Axle ratio availability '67 427, 390 and 400 HP
WR four-speed: 3.08 STD, 3,36 OPT
CR four-speed: 3.36 STD, 3.08, 3.55, 3.70 OPT
PG: Same as CR four-speed except with A/C: 3.08 STD, no OPT ratios
Assuming the speedometer gears are correct for the OE installed axle:
Installed axle ratio = top gear revs @ 60/760
Duke
WR four-speed: 3.08 STD, 3,36 OPT
CR four-speed: 3.36 STD, 3.08, 3.55, 3.70 OPT
PG: Same as CR four-speed except with A/C: 3.08 STD, no OPT ratios
Assuming the speedometer gears are correct for the OE installed axle:
Installed axle ratio = top gear revs @ 60/760
Duke
Last edited by SWCDuke; 05-18-2017 at 11:06 AM.
05-18-2017, 12:50 PM
#6
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I thought there was a directive or something that went out for multiple reasons! The belts would jump out of the non-deep groove pulleys and the rpms! I know some like 3 belt deep groove pulleys were released, pretty rare things and I could not off the top of my memory tell you on what years or cars!
Last edited by TCracingCA; 05-18-2017 at 12:51 PM.