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1965 Impala SS 396 Convertible
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34 Posts
Discussion Starter · #1 ·
My recently purchased '65 has aftermarket power brakes that the previous owner installed. However, at the same time he installed a rebuilt 396 with a hot cam that will only get me 15 inches of vacuum at idle. My mechanic says 18 " are needed, others have said 15-16" is OK. Is it worth installing an electric vacuum pump to get 3 more inches? The car is hard to stop, so any improvement in breaking performance would be a good idea. I am currently going through the brake hardware but so far, all the rest looks OK, I could also swap out the cam for a stock one, I guess. I don't really need the extra performance nor the lumpy idle, as I plan to use the car as just a cruiser. Any thoughts Thanks!
 

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1961 Impala 2 Door Sedan
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103 Posts
Unless you have drivability issues with the engine I wouldn't go into it to fix a braking problem. Can you get the wheels to lock up? If so, then you are getting enough assist to get the maximum braking performance and it's about driver effort, which the vacuum pump will help with.

IDK what '65 originally came with, but I feel my Impala stopped better and had better feel with the original 1961 single pot, non-assist, 4 wheel drums than it does with the dual reservoir, power booster front disc conversion.
 

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1965 Impala SS 396 Convertible
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34 Posts
Discussion Starter · #3 ·
Thanks, cintocrunch. Makes sense. It's at the shop having some front-end work done. When I get it back, I'll find a safe place to do some brake testing. Thanks for the advice--I didn't really want to tear into the engine yet! I have heard others confirm that their cars worked better with drums all around, -- Interesting.
 

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one way to look at it is they built using drum brakes back then. if the drum brakes were verified by the factory as adequate, then they probably are. however, other things I like to consider are that was 50+ yrs ago and:
1) people drive a lot faster now which requires better brakes
2) if better brakes are available (disc), why wouldn't you upgrade?

btw, my '65 SS convertible with 327/Powerglide has drums and a single master cylinder with booster. it's all original, should I upgrade for safety's sake to dual master cylinder and disc in front? or leave it original and take the risk?
 

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1961 Impala 2 Door Sedan
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103 Posts
one way to look at it is they built using drum brakes back then. if the drum brakes were verified by the factory as adequate, then they probably are. however, other things I like to consider are that was 50+ yrs ago and:
1) people drive a lot faster now which requires better brakes
2) if better brakes are available (disc), why wouldn't you upgrade?

btw, my '65 SS convertible with 327/Powerglide has drums and a single master cylinder with booster. it's all original, should I upgrade for safety's sake to dual master cylinder and disc in front? or leave it original and take the risk?
If I had to do it again I'd upgrade to the dual reservoir master cylinder but that's it. I like that extra safety element and if you keep the old master cylinder and can save the old hard lines you can easily revert it back for originality (or the next owner).

I did keep all of my old parts so technically I could go back. The performance is there on the discs it's the feel that's lacking. It honestly used to feel like a modern car in modulation/feedback, now it's more numb so less feedback but more travel still means more braking.
 
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