Wild Cam, 9lbs of vaccume in gear, VERY bad power brakes

[fasterthanu]

Please help. I am running dual edelbrock 1405's. I have a full race cam. I have been running this for a while. Power Brakes suck. New calipers, pads, and master cylinder all around. I only have 8-9lbs of vaccume in gear. I KNOW the power booster is good, I ran a line from my dads cadillac that has 15lbs of vaccume to it, it then stops on a dime. I see those vaccume canisters listed for cars with wild cams so the power brakes work. Do they actually work? I mean, all it can do is store vaccume in there, and create more volume for the powerbooster, they can't actually create more lbs of vaccume, can they? Anybody running these?

 

[woobie1966]

i am not currently using a can, but i used t oown a 68 camaro with supercharger and healthy cam, i put a can on to assist with vacum problem similar to yours. long story short, it helped quite a bit, i didnt have a guage, so i dont know if it increased lbs of vacum . they are pretty cheap if i remember right, just got to find a place for it under the hood
mike

 

[1979toy]

When you close the throttle there is more vacuum created, in your engine maybe only 13 or 14 inches, but it's enough to improve your braking if you've got a cannister to store it in until you need it. Remember the vacuum cannister, like the booster, has a one way check valve to hold vacuum.
If you've been driving the car and the one way valve at the booster is working correctly and you still don't have enough braking power you may want to look at a hydro boost brake system or a vacuum pump.

 

[SwaveDave]

Im running 10 " of vaccuum with my hydr. roller cam, and the power brakes work ok. If you want a good used electric vaccuum pump which ive cleaned up and painted...i have one off of a 1980's Cadillac V-6 . It works good and is fairly quite too. Ill sell it to you cheap .

Dave

 

[fasterthanu]

SwaveDave, I am going to try the vaccuume canister my dad made for me this weekend. Just curious, if it doesn't work, what do you want for your vaccuume pump? Thanks
Joe

 

[SwaveDave]

$25 and ill pay for the shipping to you via Parcel Post.

Im sure the canister will work ok for you. Make sure you have a functioning checkvalve with it too, so the vaccuum gets stored.

Dave

 

[fasterthanu]

SwaveDave, I live in Arlington Heights IL. Is there anyway I can meet up with you, I will drive up there and pick it up if your still in Lake Villa.

 

[mapman]

Have you considered the power brake units that run off the powersteering pump (no vacuum)?

 

[SwaveDave]

Faster,

Yes., im still in Lake Villa . If you email me at fast1970vette@webtv.net ...ill give you directions on how to get here. Its straight up Route 83 almost all the way. Easy to find.
Dave

 

[69MyWay]

If the vacuum pump does not work out, you can always ditch the vacuum booster and go with the Hydraboost system as seen in the supporting vendors on this site.

Plus, you could ditch the vacuum headlights and upgrade to my fully electric.

That would eliminate all vacuum accessories except your a/c and cruise control. Those can be reworked as well.

 

[mgms_1968]

Well I use to have a car with a 396 that had a 305 magnum comp cam. At ideal the car had about 4-5 in-Hg vacuum. I also had a power brake setup. To solve the problem, I installed a vacuum can. I also add two vacuum gauges one to monitor the engine and another to monitor the can itself. When drive at speed I would have decent vacuum signal and the brake worked normally. When in traffic the vacuum was low but the can would have a supply of vacuum, therefore the brakes work fine. When I would notice that the vacuum was low on vacuum I would tap the throttle and would re-supply the vacuum can.

 

[WhalePirot]

the Hydraboost system

Anybody using this?

Any comments on the experience?

I read that rodders build these systems for lots le$$. My time is worth something and I want a good system.

TIA.

mike

 

[MaineShark]

How soon do you want to know? I'm thinking I'm going to install one this summer. I want to do something to celebrate the car's 25th birthday in August, and I originally planned on a new tranny, but I think maybe I should work on the "whoa" before I work on the "go"...

Joe

 

[WhalePirot]

How soon do you want to know?

Yesterday is fine.

A partial search: The 1984-1985 Grand Nationals and Turbo Regals came equipped with a power brake system known as "Hydroboost". This system used a hydraulic cylinder fed by the power steering pump to provide assist for the brakes. While the system was effective, it had drawbacks. The first, since it was hydraulic, it was inevitably prone to leaks. The surest sign that your Hydroboost system needed attention was a trickle of power steering fluid down the firewall (on the outside if you were lucky). Another drawback was that if the belt slipped, due to splashed water from a puddle, for instance, you not only lost power steering but most of you brakes as well. Not a pleasant experience in a rain storm. Another drawback was cost. A new Hydroboost cylinder from GM runs upwards of $800, and a rebuilt one is $125 or better as of this writing.


http://www.gmc.com/gmcjsp/yukon/specs_safety.jsp?vehicle=yukondenali

The hydroboost brake booster utilizes the vehicle's power steering pump pressure as the energy source for providing brake assist (rather than the engine vacuum, as do vehicles equipped with a vacuum brake booster). Brake assist with the hydroboost is not affected by higher elevations since its energy source is not affected by elevation. The driver may also benefit from the greater total assist available from the hydroboost. The vehicle's brake performance is enhanced by the fast response of the hydroboost.

Vanco Power Brake Supply near los Angeles does units for jeeps and I've asked about Vettes.

mike

 

[GerryLP]

Faster,

Have you experimented with adjusting the idle speed upwards to improve your vaccume signal? On my XE274 the engine went from 7" of vaccume to 13" of vaccume just by adjusting the idle from 700 to 950 rpm. I have a Holley carb, and after adjusting the idle mixture (adjusted the idle mixture needles to obtain the highest vaccume signal possible), I adjusted the idle speed and gained 6" of vaccume signal. And by the way, I am at 5,000' of altitude.

You could also go with smaller carbs....

 

[MaineShark]

The guys at Hyrdatech are very helpful.

$600 for the whole kit, and you can add a new master cylinder for $90. I think this is going to be my next modification...

Joe

 

[WhalePirot]

More on vacuum/hydraulics

Van at Vanco Power Brake Supply just called, Very helpful!!

We chatted a while and the net is:
"Decide how you will drive the car". (Have I heard that B4?)

"Use a hydraboost for very heavy or very fast cars. The 1-1 1/2" of travel on our brakes pedals would be maximum braking (locked wheels) with the hydraulic booster. They are immediate, like power steering." They also have drawbacks, primarily loss of pressure (brakes AND steering) from failed or slipping belts, bad pumps or stalled engines.

I asked about loss of boost to my steering and he said the PS pump must be rebuilt to deliver more fluid; "a drilled hole and some washers, but done professionally".

They are a small, family owned biz and redo boosters for our cars. He feels they are of low quality and fail rather a lot. The '84 is smaller and delivers a bit less oomph than the later ones.

His recommend to me? Get a Delco electric vacuum pump and see how I like it. They are smart (demand driven) and used on cars such as '80s Caddys and four-banger Skylarks of similar vintage. Junkyard cost whold be very low; new cost is rather low, nuch more than the hydra and the install simple. (VANCO doesn't sell them, BTW.) If I need more brakes, which is doubtful, I can spend the $600 for a hydraboosted setup.

Gawd, I luv guys who have been there, know IT, stand to gain naught, yet tell the simple, unembellished truth. If this works, I may send the guy a C-note thanks you.
mike

 

[MaineShark]

One thing to watch, though, is that the C4 and C3 brakes are different.

A couple things, from my research into this:

Good boosters have a pressure reserve, so you don't lose brakes if the engine stalls (just like vacuum brakes have a vacuum reserve).

The C4 booster has a smaller inner diameter than the C3 booster. Much smaller (15/16 vs 1 1/8). That's a hair under 70% of the piston area. So, recommendations for a C4 won't necessarily translate over to a C3.

And, regarding the "does it need it" issue, I always feel that leaning towards the "overbuilt" side is better, especially when it comes to brakes. Better too much braking, than too little.

That said, I'll know more in August and September, I'm sure...

Joe