I really need to get a vacuum pump on my car for the brakes.

I also wouldnt mind a vacuum pump on the engine itself to help the rings seal.

Is there anyway to kill two birds with one stone? i.e. use just one pump for brake booster and also an evac system?

Suggestions on what type of pump to get, I was looking at the SSBC electric booster pump, but I guess i wouldnt mind fabbing up a V belt vane style if I can evac and brake boost from it.

Also, do I need a vacuum resevoir in addition to the pump, or can the booster store enough vacuum on its own to not need a separate resevoir.

Thanks!

 

A vacuum pump for street duty is not recommended. It dries up the splash oiling to the cam and piston pins when ya get above 12 or so in. hg.Otherwise what is the use of having it.
Put an electric vacuum pump on it with a can. Have the pump set up to come on at??? in. of vacuum and go off at??? in. vacuum. 10 in. will do the brakes and air if ya don't repeatedly hit the brakes.If ya got 10 in. put a can on it and it will help and ya may not have to buy a pump.

 

Ya i dont have 10 inches at idle, lol. Doing the MAP math i have about 7 inches. Even on decel in gear the braking is weak, just too much cam (259/270) and the big intake/heads seems to eat vacuum.

So that leads me to believe that a can wont help by itself.

Make sure I am following correctly, you would run a pump AND a can? I thought I had heard that the booster itself could store a little vacuum.

Thanks for the heads up on the piston pin/cam oiling, I had never heard that before. My SR lifters will take all the oil they can get at idle. Ill just stick with the breather/PCV then

 

You dynoed this damn thing yet?

 

You can limit the vacuum of the pump to 12-10" and you will be fine. Have you looked at a vacuum canister for the brakes? I would do that first. If you do the vac pump then you could have a setup where that pulls on both the engine and canister at different levels to produce enough for the brakes and not too much for the motor.

WTF do you need that big of a cam for in a street car?

Bret

 

Im running .584/.579 lift on my street car and having the same problem. Want to fix it too, and have a breather.........what can be done to help get vacuum, and what else will this effect besides the brakes? Performance?

 

the lift is not the problem it's the compression and overlap that make the problem.

Bret

 

It only has about 40 degrees of overlap in it. I didnt expect any problems???? Its actually a BES grind, will see how it does.

As for the street car thing, really isnt any more. It has quickly passed by that and is more and more of track duty. Suprisingly enough, the advertised on this cam isnt than much bigger than the 847 I had before, and the driveability is pretty nice too.

Dyno SOON. I finally got my obd2 computer and underdash harness, just need to wire and then off to dyno i go! Its only been two years since I started this motor project, lol. Been on the dyno once, pretty depressing, so I went back in and have changed bunches of stuff here and there.

On a totally unrealated note, everyone here complains about working on 4th gen cars. I just did upper and lower ball joints on my durango tonight. I dont wish that on my worst enemy. Ill stick with the f body stuff ANYDAY.

 

Ok so it's on a 112 then.... what are you around 12:1 compression?

Bret

 

Yes on a 112, 11.5 CR.

I have the exact lobes written down somewhere if you wanted to see. Just let me know

 

I could probably figure that out if I knew the lift lol.... you coule take another point of compression in that thing without too much trouble.

Bret

 

Its .630/.670 (within .001 or .002 with 1.6). I cant find the spec sheet, maybe its on my laptop?

Ya i know it could get away with a little more static, but I wanted to keep a bigger chamber on my heads in case I ever went the forced induction route. I know I know, big chamber = crappy flame travel, but its what I am working with for now.

 

Like I mentioned try a can and see if it won't store enough to keep the brakes working. If ya only got 7 in.on decell that may not be enough to stop it with the pedal pressure ya are use too.
I built a blown '94 Lighting that has 10" vacuum and no can and runs 11.10@4700lbs( wish I had that 356 in a Mustang a 9.50/60 street car) and he tows his 26' offshore race boat with it no problems until he is on the launch ramp and repeatedly hitting the brakes.

40*@.050 maybe-- more like 76-80 in the real world.

 

I tried a few things already in regaurds to that.

I tried a completly new booster. That gave me NO assist. I guess the diaphram is stiffer. I was standing on the brakes trying to get the car to stop.

I switched back to my old booster which still has crappy braking, but at least some boost. To that I added a resevoir from a blazer junkyarder. Helped a touch, but its still not enough.

Im going to order the SSBC electric pump through nickles tomorrow, should be here soon enough and will post back.

Thanks for you help larry and bret!

 

Any update on this? Looks like I'm going to need a can or pump soon myself.