FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: 67428GT500 on January 15, 2019, 02:53:22 PM
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I was curious what the OE 427 cam specs were. I noted many vehicles had power brakes with the 427. What kind of vacuum did the factory cam produce?
-Keith
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Here is all I got
The C3AZ-AA I believe is what was delivered from the factory and you probably could run power brakes with that. 306 duration, .500 lift, 78* overlap
I'm not sure the C4AE-B was only over the counter or not. 324* Duration, .500 lift, 112* overlap
I know the C4AE-B didn't have much Vac. in my 406, maybe 12 inches was the best, that was back in the day with 12 to 1 comp. That cam sure sounded good, idled about 900 with a 4 speed. A wide ration Trans or tighter gears would have made for better drivability with a 3800 lbs car.
And the big C8AX-D was definitely not going to satisfy power brakes 330* duration, .600 lift, 116*overlap
These numbers are factory specs (not at .050)
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I have my custom grind. I was just curious what the specs were as they supported power brakes, which needs about 16 inches of vacuum to work.
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I wouldn't count on a 'Double A' for power brakes. And I believe the only 427s that came with power brakes were the juice lifter ones that came in the Mercs. I believe they came with GT or perhaps CJ cams.
KS
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Several 427 cars came with power assisted brakes. My cam isn't that radical, but enough to lower the vacuum to about the minimum that a Midland-Ross booster will function with. I was just curious how the OE 427 cam compares with what I am running.
-Keith
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Several 427 cars came with power assisted brakes. My cam isn't that radical, but enough to lower the vacuum to about the minimum that a Midland-Ross booster will function with. I was just curious how the OE 427 cam compares with what I am running.
-Keith
Which 427 cars came with power brakes? Not doubting you cuz the "AA" cam would work ok with them but I just never heard of that combo.
Several 427 Cam grinds:
The "AA" cam from the 352/360hp 390/275hp 390/401hp 406/385hp 406/405hp 427/410-LR (maybe the 427-MR too, conflicting info)
228-228-114.5 at .050, maybe 14-15" vacuum at idle, works fine with stock stall automatic & power brakes.
The c3az-k cam, I've heard it called optional but also that it was stock on the 427-8v-LR:
244-244-114.5 at .050, maybe 8-9" vacuum at about 700-800rpm, marginal w power brakes, "good for one stop" anyway. I've run this cam with power brakes for years. It was the wildest production cam.
c4ae-b cam, factory stock on the Thunderbolt and LWG cars, if you call that production.
244-244-106 at .050, same as previous cam but a LOT wilder with the closer centers. I doubt if power brakes would work.
c8ax-d cam, factory stock on the 67-69 Tunnel Port factory Fairlane cars. Oh wait, there weren't any.
272-272-107 at .050, but you wouldn't want power brakes on that car anyway.
Finally, the hydraulic 427 of 1968 used the 390gt/428cj cam at
207-220-116 at .050, so smooth you can barely tell it from the vanilla cam, maybe 16-17" vacuum.
I'm pretty sure these came with a power brake option but I never heard of any other 427's offered that way.