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power brake vac #2910505
04/15/21 02:28 PM
04/15/21 02:28 PM
Joined: Jan 2003
Posts: 1,599
westerly, ri. usa
4
440lebaron Offline OP
pro stock
440lebaron  Offline OP
pro stock
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Joined: Jan 2003
Posts: 1,599
westerly, ri. usa
hi,
1975 b-body 400 race cam no specs yet, (drag race no street use) anybody run power brakes? hard pedal? switch to manual??
thanks
gary


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Re: power brake vac [Re: 440lebaron] #2910564
04/15/21 04:55 PM
04/15/21 04:55 PM
Joined: May 2019
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Sniper Offline
master
Sniper  Offline
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Cam specs are somewhat irrelevant.

How much vacuum you have is, I've heard 17"/hg minimum.

If you have less than that there are things that can be done. Adding a vacuum pump is one. Going with manual brakes is another.

Since all my rides are manual brake setups it's not really an issue for me.

Re: power brake vac [Re: Sniper] #2910899
04/16/21 11:38 AM
04/16/21 11:38 AM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline
"Butt Crack Bob"
moparx  Offline
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north of coder
then there is the question of a single diaphragm or a dual diaphragm booster, and the booster size.
disc brakes usually use a dual diaphragm booster, while drums use a single one, but if enough vacuum is produced with a pump, maybe a single unit booster would work ?
beer

Re: power brake vac [Re: moparx] #2910945
04/16/21 01:16 PM
04/16/21 01:16 PM
Joined: Jan 2003
Posts: 1,753
Windsor, ON, Canada
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Diplomat360 Offline
top fuel
Diplomat360  Offline
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Windsor, ON, Canada
Originally Posted by moparx
then there is the question of a single diaphragm or a dual diaphragm booster, and the booster size. beer

This right there is a great point!

I have a dual-chamber booster on my Dippy coupe, the hydraulic flat tappet cam only pulls about 7" of vac, and it's dipped lower, right down to 5" at idle numerous times (mostly when I was tuning and trying a few things here and there), point being: my brakes have NEVER gone away!

This is with discs up front and drums at the back.

Re: power brake vac [Re: Diplomat360] #2911547
04/18/21 09:38 AM
04/18/21 09:38 AM
Joined: Jan 2003
Posts: 1,599
westerly, ri. usa
4
440lebaron Offline OP
pro stock
440lebaron  Offline OP
pro stock
4

Joined: Jan 2003
Posts: 1,599
westerly, ri. usa
Thanks I'll try it as is , if I have a issue I'll add a pump


all parts are sold as is, all parts are considered used no warranties or returns
paypal/check/money order, shipping is from zip 02891, buyer pays paypal fees 24% IRS 1099A plus 3% of part price, check/money order preferred
site is not monitored 24/7 there might be a delay in response

Re: power brake vac [Re: 440lebaron] #2911559
04/18/21 10:34 AM
04/18/21 10:34 AM
Joined: Jan 2021
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rust belt
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Moparite Offline
super stock
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rust belt

Re: power brake vac [Re: Moparite] #2911608
04/18/21 12:38 PM
04/18/21 12:38 PM
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Posts: 6,175
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Sniper Offline
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Originally Posted by Moparite


The booster is one big assed vacuum reservoir and neither helps if you don't have enough vacuum to begin with,

Re: power brake vac [Re: Sniper] #2912106
04/19/21 08:59 PM
04/19/21 08:59 PM
Joined: Jan 2003
Posts: 15,197
Omaha Ne
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TJP Offline
I Live Here
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I Live Here
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Joined: Jan 2003
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Omaha Ne
Originally Posted by Sniper
Originally Posted by Moparite


The booster is one big assed vacuum reservoir and neither helps if you don't have enough vacuum to begin with,


The idea behind the reservoir is that it will store the additional higher vacuum achieved while cruising at higher RPMs via a check valve. That higher vacuum will then be available at lower RPM's / vacuum. Might work in a marginal situation but I have had little success on customers cars so the pump gets my vote. I believe the reservoirs are more of a snake oil / band aid approach. but they are good at doing what they are marketed for, getting money from your wallet to the suppliers / manufacturers whistling twocents beer







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