Has anyone ever installed a Hydro-Boost Brake System in a 71 Skylark 350? With my vacuum being low because of my cam my brakes are not what they should be, even with a vacuum booster. I saw a show last night where they put the system on a 67 GTO with the same issue and it seemed to work rather well. I was wonder how complicated the install is and if the results are worth the cost.
Hydraboost comes stock on the turbo cars since there is no vacuum under boost. It works well on them.
Might go check it out a Chevy forum. I bet tons of those guys have done it. I don't see why it wouldn't work, though. The master cylinders aren't all that different, really. If I had this problem, I'd just swap out the power disc brakes for manual. That only takes master cylinder replacement, and possibly different rear wheel cylinders. I can't be bothered to go look up the parts online, though. Doing it that way will also reduce the parasitic losses used for brake boost by the power steering pump. I'm thinking of going to manual steering to help reduce the anemic performance of my car. It was rebuilt prior to my purchase, and holds good oil pressure (15 PSI at a hot idle), but it is no barnstormer. The cam lobes are probably worn down. I'll get into it one day.
Yes, you can buy one from Amazon: http://www.amazon.com/Power-Service-Hydro-Boost-Booster-Chevelle/dp/B00BMVD292 And another one: http://www.powerbrakeservice.net/new-19641972-chevelle-hydroboost.html
Considering it was stock on the 84 T-type and Grand National, as well as THOUSANDS of other GM trucks and quite a few cars, I'd say it is pretty reliable. Only downside is that you REALLY notice it if the engine dies: no assist on steering AND no assist on brakes. Your driver's side seat cover will know this after the FIRST time (T1H2H0, look that chemical formula up in a mirror)). Many aftermarket companies make kits for LOTS of "old school" cars; There was even an article in one of the mainstream car magazines several years ago about doing it on the cheap. I got the entire setup out of a GMC /Chevy Astro van or its cousin from a junkyard for $25: reservoir, hoses, master cylinder,booster, distribution block, hard lines; And then went back and re-read the article... It was for set-up on a 64-67 GM A-body. Oh well, at least I had a fun day in the junkyard. Parts are still sitting on the shelf; Didn't have anything that actually needed brake work...
I don't believe the GN brakes were ever hydro boost brakes. They used the Powermaster which I believe was an electric motor power assist. They were notoriously troublesome. I remember the spherical part they called the accumulator would go bad leaving you with a hard brake pedal and no brakes.You could convert over to a hydroboost system, or vacuum brake assist, but GNs did not come like that stock.
Larry, the 1984 T-types and Grand Nationals had the hydroboost; 1985 had Powermaster with angular reservoir, 1986 & 1987 had Powermaster with rectangular reservoir. Try finding a CORRECT power steering pump for a 1984 T-type !!!
How low is the vacuum reading? Even 12 inches should give you a soft pedal. Do have a really big cam in it?
TA 284 cam and requires vacuum canister at the moment. Vacuum extremely low, if I recall 5-7 inches but I may be wrong.
Interesting, the TA 284 seems like a pretty mild cam. My monster TA308 makes 5-7 inches of vacuum. Maybe you could verify and double check the vacuum reading. Shouldnt that cam make something like 12 inches of vacuum?
I am almost certain it is not anywhere near 12. I do recall when the engine was re-built and the vacuum was low it was allegedly checked for leaks and nothing was found. I then had it checked again after a few hundred miles and again nothing was found and the canister was added. Where might I be losing vacuum from? Also if I were to check the current vacuum at idle where would the best source to check be?
Any port that has manifold vacuum going to it. On a Q-jet, you can use the large port on the front of the carb on the passenger side. Or pull the vacuum line off going to the trans and check it there. To check for a leak, slowly smother the air at the air horn of the carb. If it has a leak, you'll see the vacuum reading to go up. You can try pulling off the vacuum hose going to the booster and make sure you have vacuum at the hose and no restrictions
It could be leaking internally at the intake to head. Very difficult to detect from the outside. If you block off ALL the vacuum connections including the PCV, power brake and Transmission vacuum modulator, everything, then run the engine, you can open the oil fill cap and check there. There should be crank case pressure. If there is vacuum, there is an internal leak. Put a piece of paper over the opening and see if there is vacuum or pressure. There is no reason for a cam like that to only make 5-7" of vacuum.
