Thread: Vacuum Reserve Canister Plumbing?

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I ordered a vacuum canister last week and have a question about placement. My engine makes only 9 " of vacuum at idle, 18" at 1200 RPM and I am running a dual diaphram 7" booster, one good stop - then hard pedal, but you can still lock'em up.
My question is on placement of the can. I figure it should as close to the booster as possible but I'm going to have to run about 5'of
vacuum hose from the manifold to the can then 2' back to the booster. Will this have an adverse effect on what what I'm trying to accomplish? I don't want to run a noisey Vac pump if possible!

I can't imagin it being a problem but I would run tubing as much as possible. Less chance of hose collapse

The event that will cause you the most trouble will be brake applications several times in a row @ less then 1200 RPMs. That canister is not going to overcome that, if you are trying to get those brakes to work like your dd, you already have the answer.

I found putting the electric pump under the car and under the drivers seat along with the side pipes took care of the noise.

I'm with Charlie!!! I'd limit the vacuum hose to as short of pieces as possible and use tubing for the line along with some quality connectors!

The canister location is not critical for the operation 9in or 18in will be the same through out the system. It will only hit one lick at full pressure, however it will take longer to recover cause of the added volume created by the canister, I'll throw in the extra volume of the lines from the run length just to nick pick this thing further.

The tubing is not a bad idea, but if you're running a good vacuum rated hose you should be OK with hose. I assume that you have a check valve between your vacuum source and the booster/canister so that your residual vacuum is held in the canister at idle, not bled back into the engine?

I guess I'm going to order a Vac pump! I like the looks of the Summit 760152 made by CVR Racing in Canada. It's self contained and sells for $269.95, CVR sells the same pump for $328.39. It's probably not a good idea to add the canister in line, it might screw-up the pump recovery? besides, that's more junk hanging off the bottom of the car.
It's time to solve the problem and quit screwin' around!

Why not try a canister and check valve and see what it does? If it fixes your problem you're done, and if not then you can spring for the pump. My logic is, how many times are you under way for extended periods at idle rpm, low vacuum conditions, and then need a panic stop? 99% of the time you're going to be at better vacuum for some period of time, charging your canister, and it may give you multiple brake applications once you're at your lowest vacuum. This is a dynamic system with variables, and your idle vacuum is not that far below what is needed for optimum operation. I'd find out what the canister does for you, and then make the decision on the pump as a last step if the problem is still apparent.

Roger, The can will be here today and I was going to try that first, it's easy to mount, I,ll try it this weekend!
Then if I doesn't do the job, off It comes and I'll order the pump!
Thanks! Joe

Not going to work, it is not idle that is the gotcha, the weak link is below the 1200 RPM range. Slowing down and back and forth movements put the car at risk of running into something. If all low speed situations were predictable and brake applications the same maybe you could chance it. Still the first hit of the peddle drops the vac range to a less then a desirable working pressure. You can analyze this to death but until one experiences it one cannot grasp the totality of the situation.

However putting SAFETY first this car needs a constant reliable and steady vac source. Place oneself into this persons shoes and ask yourself do I want to drive with maybe brakes, a hard peddle is not a good idea. Want to experience what he is talking about disconnect the vac line on any car and back out of the drive way.

He is making the right decsion and the not wasting his time hacking the power assist system. Even with a check in th system it still will only produce one power assist brake application @ below 1200 RPM, just the way it works.

??how many times are you under way for extended periods at idle rpm, low vacuum conditions ?? ever been in a line of cars entering a car show. More times then one realizes.

Well, I went and did some reading and Pepi's right according to this brake website - Master Power Brakes - Reference/FAQs: Power Boosters Seems to me that the canister should store enough energy to help, but it appears that's not the case. Looks like an electric pump is in your future, unless you change out your master cylinder to a non-power disc brake unit.

Thanks Roger & Pepi. I'm going to order the pump. I want consistant and reliable braking every time. Any thoughts on using the can between the pump & booster? Extra already on hand vacuum? Ya think?
I will be calling CVR to pick their brain.
11/7/12, Ordered the pump today from Summit, forget the can!

I installed my Summit 760152 vacuum pump today, I now have power brakes....consistantly, every time.
It still doesn't stop like the family sedan, but when you consider the mix of parts that we use in these cars,
I'm happy and I'll keep tweeking!
It's weird getting used to the pump running!
Thanks guys!
Joe

OK! New question. Now that I've installed the vacuum pump and have decent power assist, would there be any advantage to add
a vacuum storage canister? Would that really do anything? Seems like when you step on the brakes the pump will run either way. Maybe it would give me an extra stab! I don't know.
What do you think!
Below is a picture of the pump mounted under the floor. ( picture is upside-down )
Thanks! Joe

If you add a canister with appropriate check valves to prevent losing vacuum back through the pump when off, then your vacuum needs will be served first by the canister, and the pump will run to keep the canister charged, like the air tank on your compressor. The canister will delay the start of the pump a little bit, but will also extend the run time of the pump by the same amount of time once it starts. The only advantage you might gain is one application of the brakes if your canister is charged, and your vacuum pump fails to start, seems to me.