Vacuum reservoir for power brakes

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TRWRacing

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1973 Mild 360. It is an A/C that has power brakes and a dual connector vacuum reservoir for the heater control that is connected to the v-nipple on the intake manifold. The other connector goes to the power brake booster. I am looking to add a larger reservoir for the power brakes since I am getting about 14-15” of vacuum.

Can I add this reservoir to the vacuum connector on the intake connector and then to the power brake booster leaving original existing canister for the heater control?

Thanks
 
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With 14-15" of vacuum you shouldn't need a reservoir for the brakes, that should be plenty of vacuum if everything is working properly.

I'd swap to manual brakes long before I added a reservoir. I swap all my cars to manual brakes anyway, I prefer the pedal feel and brake control with a 15/16" master cylinder to any of the vacuum boosted set ups out there.

If you still want to add the vacuum reservoir, there shouldn't be any reason you couldn't add the reservoir off of the intake connector and leave the original alone for the heater control. Shouldn't hurt anything.
 
Vacuum seems low for a "mild" engine. How mild is your mild? Possible leak?
 
It’s an MRL 360 Cruiser.

LA 360 Block
Summit Cam
284/228 .480 lift 112* LSA 108* ICL
Compression 9:1
2.02 / 1.60 valves stock heads mild porting
Airgap intake
Edelbrock 600 cfm 1406
73 340 exhaust manifolds

I have power brakes, just wish a little more assist.
 
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Hmmm. More assist? That vacuum level really shouldn't be messing with the brakes unless you're talking about extended, repeated brake applications. If the assist is always constant, but less than you'd like, you may have a master cylinder bore sizing issue.
 
I’m not sure how the pedal should feel. I’ve only driven modern cars with power brakes. My first car (‘71 Demon had manual drums).

I do know the master cylinder and power booster were replaced a few years ago with NAPA parts. I just assumed 15” of vacuum was low.
 
I’m not sure how the pedal should feel. I’ve only driven modern cars with power brakes. My first car (‘71 Demon had manual drums).

I do know the master cylinder and power booster were replaced a few years ago with NAPA parts. I just assumed 15” of vacuum was low.

15” of vacuum at idle really isn’t low. I mean, it’s probably a couple points lower than a 100% bone stock engine in good tune but it shouldn’t cause any brake booster issues. Typically you can run down to about 12” before the booster starts having issues.

And even then it wouldn’t be constant. During low vacuum situations it might come through as a lack of assist, but during high vacuum situations it would be normal. So, if you constantly have low boost assist you probably have something else going on.
 
I'm with 72bluNblu on this. 14" of vacuum is enough for your power brakes. I'm running a bigger cam than you and have about 11" at the booster and my brakes work fine. You may have a leak in the booster itself.
 
Hay... How do like that Summit cam? I've been always wanting to try one but never have.
 
Hay... How do like that Summit cam? I've been always wanting to try one but never have.

It’s good for what it is. I wanted a 360 close in performance to the ‘73 340 that was pulled and sitting in the garage. The 340 rebuild will be my son’s project.
 
The reservoir is........... just a reservoir............ just like the big chamber on your current booster. Adding one only extends the number of stops you can make on a stalled engine. It does not increase your braking performance one little bit on an already properly working system.
Your biggest enemy is the combination of; an Ica around 72*, in a 9.0 engine,with log manifolds. I have no idea how you coaxed 14/15 inches of idle vacuum out of it, unless she's idling really high.. or has Rhoads lifters.
Ima thinking to get a second opinion as to that vacuum number.
As Blu already said, the 15/16 M/C is a nice size.
 
Keep in mind that drum brakes feel very different than modern disc's and they suffer from brake fade quickly.
 
Idle is set at to 800 rpm in park. The cam was a MRL pick... which in hindsight, I would have picked a different engine builder. With my kids college coming up in the fall and a car driven about 500 miles in the summer. I will have to live with it for a few years.

Would a different intake manifold be better? Recommendations? I really don't care for the chinese knock air-gap that MRL put on it.
 
The reservoir is........... just a reservoir............ just like the big chamber on your current booster. Adding one only extends the number of stops you can make on a stalled engine. It does not increase your braking performance one little bit on an already properly working system.
Your biggest enemy is the combination of; an Ica around 72*, in a 9.0 engine,with log manifolds. I have no idea how you coaxed 14/15 inches of idle vacuum out of it, unless she's idling really high.. or has Rhoads lifters.
Ima thinking to get a second opinion as to that vacuum number.
As Blu already said, the 15/16 M/C is a nice size.

Here is the MRL paperwork

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You said that was a solid-lifter cam right?
Do I recall .016/.016 lash?

I think I would just lash the valves a lil looser and see what happens. Say .020 intake/.024 exhaust This will make your 285cam behave like maybe one cam size smaller, with a lot less overlap and therefore idle with a higher vacuum. Just be sure there is room in the Scr to do this without getting into detonation.
This combo also wants bigger gears and a looser TC. The looser TC allows the engine to spool up before moving out. This slight delay pops up the vacuum; and if the booster vacuum has fallen off from say an extended idle-time, now it will jump to attention. So now you don't really care about idle-vacuum, unless your booster is just not working right;that's another story. In my experience, at low vacuum levels,the dual-diaphragms do not work as well as the big singles. Otherwise they seem to work fine.

Ok so the Summit site says FTH ,not solid, so I guess that ain't gonna work so good with hydraulics.
Or will it? You can run Rhoads on those lobes and get a ton of torque at low-rpm. Or you can run anti-pumpups with some lash added. Some HD lifters with circlip retainers are already APs and being an MRL engine, I suppose you may already have those; IDK.But in any case, adjustable gear would be required
 
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