Power brake vacuum questions:

[bentpshrods]

 I have a 71 340 that I rebuilt about 25 years ago. I bored it .030 over-10.5:1 pistons-mild head work-headers. I put in the purple shaft 292 duration/509" lift cam. At the time I had no clue that a bigger cam could effect vacuum. This last fall I got the cuda running again after sitting for a long long time. When I tried to power brake (AT-3000 stall conv. -PDBrakes) and light up the tires the brakes hardly held it back. What I was wondering  is if I should go with a smaller dur. cam or I noticed in JEGS that you can get a vacuum reserve canisters. These are small 5" x 7" cans that are supposed to give an extra shot of vacuum. Do these work? I really like the rough idle of a big cam and want a strong street/some strip action setup but with brakes that will work!!! Any thoughts on these booster cans.        Thanks   Doug

[highspeeddirt]

I've never used the vacuum reserve cans myself, but the people I've talked to say they work well.  They are suppose store some vacuum you build at higher rpm's for use at the lower rpm's.  Like Isaid thats what I've been told, not my personal expirience.   

[Chryco Psycho]

Vacuum cans definatly work , the .509 is a big cam , you can get a lot more lift with less duration & it will run better but depending what you are doing specifically with the car would make a dofference in the cam choice

[matt63]

Don't you need a vacuum pump also with this kind of set-up?

[dlrogers]

 
How do!
I've recently bought a '71 challenger in from the states - it has a performance cam that affects the vaccuum. To make up for it, there is a vaccuum pump installed separately to provide vaccuum to the booster. It does work well, brakes are fine and will no doubt be even better once I get discs all around. There is an issue with noise though - I'm not keen on that bit so would welcome any other input!
Cheers
David

[kingtroll]

I have a 71 340 that I rebuilt about 25 years ago. I bored it .030 over-10.5:1 pistons-mild head work-headers. I put in the purple shaft 292 duration/509" lift cam. At the time I had no clue that a bigger cam could effect vacuum. This last fall I got the cuda running again after sitting for a long long time. When I tried to power brake (AT-3000 stall conv. -PDBrakes) and light up the tires the brakes hardly held it back. What I was wondering  is if I should go with a smaller dur. cam or I noticed in JEGS that you can get a vacuum reserve canisters. These are small 5" x 7" cans that are supposed to give an extra shot of vacuum. Do these work? I really like the rough idle of a big cam and want a strong street/some strip action setup but with brakes that will work!!! Any thoughts on these booster cans.        Thanks   Doug

I just wanted to add on to this older post and see if anyone has any suggestions to this problem which I also have with losing power brakes. I have installed a vacuum canister in my car and it does not seem to be helping. I have a guage attached to my canister and it remains very low in vacuum. I am considering installing a electric vaccum pump but am hesistant because it is much more expensive and I am afraid it won't work. Any suggestions would be appreciated. The canister I do have is attached according to the instructions given with it. I figured the electric pump would produce it's own vacuum and not depend on build up like the one I current have. The one I have is the one from summit part number  SUM-G1461.
I am so close to getting back on the road but I am afraid of not being able to stop. That could be a real problem.




Thanks

Mike

[1 Wild R/T]

Rather then spend allot of money for the MP brakes vacuum pump, why not go to a wrecking yard & get one off a mid 80's GM fwd caddie or a late 70's diesel powered car...typically $25.00 then spend some time making sure it is well isolated to reduce the noise...Most guys mount them in the drivers wheelwell off the brace from the cowl to the shock tower area..

[kingtroll]

Rather then spend allot of money for the MP brakes vacuum pump, why not go to a wrecking yard & get one off a mid 80's GM fwd caddie or a late 70's diesel powered car...typically $25.00 then spend some time making sure it is well isolated to reduce the noise...Most guys mount them in the drivers wheelwell off the brace from the cowl to the shock tower area..

Thanks for the advice. My problem is time. I left it at the shop and I would have to find the time to go over to the wrecking yard and see what they have. There is one about 40 mins from my house. I definately need to save what I can and where I can.

[dlrogers]

The electric pumps certainly work - but as I said, my setup is so noisy! Like Wild RT says - gotta isolate it well
Cheers

[kingtroll]

The electric pumps certainly work - but as I said, my setup is so noisy! Like Wild RT says - gotta isolate it well
Cheers

Where did you mount the motor?

[zerfetzen]

I just went through all of this a few months ago.  I heard that vacuum boosters, cannisters, etc., were problematic, and opted against them, and instead converted my car from power to manual brakes.  It was easy and I love it, all the difference in the world.  The cam for my 440 is .545 lift and 297 duration, and I swear it was operating on 1% of brake power with power brakes.  With manual brakes, they are like a rock.  Benefits of switching from power to manual brakes are:

I can actually feel the road.
It's marginally lighter weight.
It's mechanically simpler (therefore better in my book).
I have absolutely ZERO worry about brakes due to a big cam.

I'd say there are no drawbacks.  Some people think that manual brakes take more effort for braking, but I don't think so, it's pretty close.

What I did:

I got a complete Baer Sport Brake system (expensive, but excellent quality, and fairly easy to install)
Got a manual brake pushrod
Mounted the new master cylinder directly on the firewall

That's about it.  100% solution that is 100% better.  Just my 2 cents.

[dwbiggs]

Doesn't somebody make an assist unit that works off PS fluid...if you have PS.  I saw it in a Mopar mag recently.

Dan

[highspeeddirt]

It's called Hydroboost.

http://www.hydratechbraking.com/

Its been a while but I emailed them  with questions about a system for the 72 cuda I used to have and they were very knowledgable, and could do me a system even though it wasn't listed on their site.  Hope this helps.
                                                       
                                                    HSD 

[kingtroll]

Well just wanted to say that my car stops pretty well now. I just replaced the brake booster. My brake vacuum canister has a small gauge and it read only 4. After replacing the brake booster it now reads 15. I thought the after market cam was the sole culprit of vacuum loss but apparently the brake booster was defective as well. Just a thought for you that buy a old Cuda and have the same problem of vacuum loss and install a brake vacuum reservoir canister. Take my advice and buy the gauge.

[HemiDog]

It's called Hydroboost.

http://www.hydratechbraking.com/

Its been a while but I emailed them  with questions about a system for the 72 cuda I used to have and they were very knowledgable, and could do me a system even though it wasn't listed on their site.  Hope this helps.
                                                       
                                                    HSD 

I bought one from these guys and when you call, expect to be talking for a while.  It is a good thing.  They are super knowledgeable about their product and setup.  They gave me some recommendations about master cylinders, fluid reservoirs, and power steering pumps that totally make sense.  They need to know which ones you using so they get the correct fittings and hoses in the kit.  We even talked about their experiences they had on the Power Tour.    The kit itself, is very good quality.  I can't comment on installation because I am waiting on my motor to come in first.  That is the big reason I decided to go with the Hydratech system.  I wanted to be sure I can clear the Hemi with Stage V heads.