Brake Booster Questions HELP!!!
Thread Starter
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Brake Booster Questions HELP!!!
So after my engine upgrade I installed a Edelbrock Performer RPM intake and a Holley 650 double pumper dual feed carb. A Comp 270 cam and I have around 14 on the vac gauge when I checked it. I had to drill a new hole and tap it for intake vac. I hooked the PCV valve to the big port on the base at the back of the carb and all the other vac. from the 3 port installed in the intake. I had to reduce the vac line from the brake booster to hook it to the 3 port installed in the intake. My question is can this cause a problem with the booster because I don't have very good brakes. And yes I have checked all the rotors for run out power bleed the brake system 5 times and did not get any air either time I bleed. The pedal is not spongy but it does go down to far to the floor. I was doing some reading on the internet and it said not to reduce the vac line to the booster. I have no leaks in the system and it held 10 psi with the Motion Power Bleeder. It stop but I can not lock the wheels up with a hard stop. Anyone have any advice or info that might help me Please!
Thanks
Thanks
Last edited by VictoriaVette; Apr 16, 2009 at 10:20 PM.
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
I would not reduce the size of the booster vacuum line smaller than 3/16-1/4"
restore the boosters full vacuum supply and see if that eliminates the problem and go from there
restore the boosters full vacuum supply and see if that eliminates the problem and go from there
Last edited by jimvette999; Apr 17, 2009 at 02:09 PM. Reason: spellin'
Thread Starter
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Well I worked on the 77 today changed the vac line to the booster and did not reduce it put some hose clamps on it and now I can lock the brakes up but not all the tires will slide. So I guess now I need to go back a bleed everything over but at least it stops good now! And I'm only getting around 14 on the vac gauge at idle. It slides the drivers rear and you can hear the front begin to slide they are making noise anyhow. I really think if I had not let off the brakes the front would have locked but I did not want to put a flat spot on the drivers rear. I checked the booster and could not hear any leaks and the brake pedal is hard as a rock with the engine off so the MC is fine. Also I checked and there is no way to adjust the rod behind the MC just a plain rod.
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
Well I worked on the 77 today changed the vac line to the booster and did not reduce it put some hose clamps on it and now I can lock the brakes up but not all the tires will slide. So I guess now I need to go back a bleed everything over but at least it stops good now! And I'm only getting around 14 on the vac gauge at idle. It slides the drivers rear and you can hear the front begin to slide they are making noise anyhow. I really think if I had not let off the brakes the front would have locked but I did not want to put a flat spot on the drivers rear. I checked the booster and could not hear any leaks and the brake pedal is hard as a rock with the engine off so the MC is fine. Also I checked and there is no way to adjust the rod behind the MC just a plain rod.
Pro
Joined: Jun 2005
Posts: 540
Likes: 4
St. Jude Donor '09, '24
Do a search here in the Forum about the Hydroboost coversion for C3s. You run the Hydroboost setup from the power steering pump instead of the vacuum from the carb and it will elimanate 95% of your brake problems. It will make your C3 stop on a dime, houstonvett
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
Check that you dont have a rubber brake hose collapsing. Replace with new SS lines flex lines if you need to update them.
After that, I would try this for bleeding:
Bleed the brakes furthest to closest.
Bleed the brakes again closest to furthest.
It's possible you somehow had air that didn't make it out, or your MC went dry, and you re-introduced air into the system accidentally.
Set your Motive power bleeder to 15PSIG.
Keep the Motive tank dry
Bleed one caliper at a time and then refill the MC after each bleeder session so you dont go dry.
Be sure that on the rear calipers, you do the inner bleeder first, then outer bleeder.
Youll get it.
Then when your done, and your foot still goes too far to the floor
, sheetcan the vacuum boost and get a hydroboost set-up. You'll be raving how this is one of the best things you did to your car. Only 1 inch of travel and then just foot-toe pressure applied from there will get you back to 0MPH quite quickly.
After that, I would try this for bleeding:
Bleed the brakes furthest to closest.
Bleed the brakes again closest to furthest.
It's possible you somehow had air that didn't make it out, or your MC went dry, and you re-introduced air into the system accidentally.
Set your Motive power bleeder to 15PSIG.
Keep the Motive tank dry
Bleed one caliper at a time and then refill the MC after each bleeder session so you dont go dry.
Be sure that on the rear calipers, you do the inner bleeder first, then outer bleeder.
Youll get it.
Then when your done, and your foot still goes too far to the floor
, sheetcan the vacuum boost and get a hydroboost set-up. You'll be raving how this is one of the best things you did to your car. Only 1 inch of travel and then just foot-toe pressure applied from there will get you back to 0MPH quite quickly.
Last edited by MN-Brent; Apr 18, 2009 at 02:52 PM.
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