I've been reading the many great posts and realized that I might have a problem with my 4-wheel power disc brake conversion I purchased for my Cutlass Supreme.

Here's the Scoop:

I've got a 350 Olds with a crane powermax cam (#804541). Lift is 484int/512exh; duration is 216 intake 228 exhaust. I've installed flat top 10.25:1 high-compression pistons and I'm running an Edelbrock performer (2711) Non-EGR intake manifold with a Edelbrock 650cfm Thunder Series carb (Electric choke). I've also installed a 2100 stall converter.

Am I going to have enough vacuum for my disc brake conversion? ...Please say yes.

 

I'd say yes.
That cam isn't too crazy.

 

That's good news. Thanks J. I've been pretty dilligent in doing my research before making any moves on the car. And everything up until now has worked out pretty well. I'm just waiting for Murphy's law to creep up and hit me in the face before this whole thing is over.

 

Oh IT WILL!!......IT WILL!!

The day I layed down the first coat of paint on my frame once the car was in a million pieces, I lost my job lol. Just make sure have your **** together before you do anything.
Lucky for me, I already have the parts and can relax, build the car, and get my unemployment until things pick back up.

 

Yeah, now that the economy is in the toilet, I imagine you and possibly I won't be the only ones with the same story. As of now I've taken care of most of the high $$ stuff and I've managed to save enough up for the paint. The thing I'm worried about is the rings not seating right when I break it in or the pre-load on the lifters being wrong and bending the rods while grinding my cam down to a piece of rebar, or some strange electrical fire that I couldn't have anticipated. Who knows right?

At any rate, I'll try to get some good pictures after the paint shop.

 

I read that you need about 12 inches to make the power brakes work. The pedal will be hard inthe mornings, but after it's warmed up, you should be fine.

If it bothers you, you could get a small vacuum pump and storage ball

 

I hope you don't have any problems, been there, done that. I have about 8 inches of vacuum at idle (built 400 Poncho). I had a drum booster on and it worked fine until the disc conversion and larger booster, then brick under the pedal time. I found through some white knuckle experience that the vacuum cans just don't work, maybe one meager stab at the brakes then whoa horse time, not to mention scary as hell. There may be situations where you just need a little help the cans may work in but I have never found it personally. The vacuum won't get any better no matter what you do, low is low. The only easy fix IMO is an eighties GM auxiliary vacuum pump with the built in automatic regulator, on evilbay once in a while for around 100-150 bucks, otherwise rare as hens teeth. There is hydro-boost but that is another whole can of worms and a major project comparatively. The aftermarket pumps they sell at brake places and speed shops are more for drag cars I think, loud and shake the whole car no matter what you do, very expensive too. I had tried them all and was getting ready to pull my hair out, they just weren't right, lucky that Summit is close and will take almost anything back. I researched more and found the GM pump was an easy solution to a big problem. They are automatic, small, very quiet, hardly draw any power, goes inline so you are still using some of your vacuum too. I put a vac gauge in just for the pump and it is always at between 17-22 inches, the needle jumps back up immediately after hitting the brakes, otherwise I would forget the pump is even there.

Just my two cents woof,
Allan

 

My 72' has disc up front, it's all of the engine upgrades and converting the back to disc that scares me. I'm sure it will be okay, but before I take it out I'll have to check and see if it's got at least 12 inches of vacuum.

It would kill me to get her done, then smack into anything...or worse drive off a cliff.

Thanks for the suggestions on the auxillary aftermarket pump for the system.

 

As a data point, my 70 W-30 has factory manual discs and stops with no problems. Consider that as an option.