I still cant build any boost at the line going nuts!

[GBGN1]

Got the s10 rear cylinders,long shoes on booth side and 275-60-15 nittos on the rear and the brakes are adjusted tight but i still cant hold it down at the line-I have vacuum brakes also.any more secrets i havent heard about -Even with the ebrake on i can only get maybe a pound of boost
thanks
Brian
1987 we4

 

[bison]

What rpm are you at at 1psi boost? What dp do you have? Maybe the flapper is not sealing the wastegate hole

 

[Brer Rabbit]

time for a trans brake.

the solution to ur problem is a few hours away. oh yeah I forgot -----sorry about Brett! Go Bears!

 

[bison]

the solution to ur problem is a few hours away. oh yeah I forgot -----sorry about Brett! Go Bears!

transbrake isnt going to help with his problem

 

[BLACK6PACK]

What turbo and what converter? Do you have a vacuum resivoir?

 

[trev0006]

is there any load on the engine at the line?

 

[Scooter3800]

Fix your exhaust leaks!

 

[Boost231]

is it spinning the tires or just wont build past 1psi. i say exhaust leaks or flapper.

 

[GBGN1]

Thanks all for the responses -except for that brett joke-still cant believe they gave him away-idiot management

Mease down pipe-it boost great
I have turbo link and everything looks good blm etc
70 ctp bb turbo new-and 3200 lu convertor-stock longblock i can hold the brakes to about 2800-3000 rpm-then the wheels start turnen
no vac resovoir

 

[JST A 6]

Also you may want to try another boost gauge. I can't hold any boost either (have vacuum brakes on the car now and I have all the parts to do the same upgrades you did but haven't gotten around to it yet) but I'm also suspecting my boost gauge to be a problem. I've noticed when I'm driving and get into boost that sometimes the gauge doesn't leave "0" smoothly--it tends to "snap" to about 5-8 psi sometimes and then it moves smoothly from that point, including coming back down to "0". Mine is a 0-30 psi VDO gauge. I've also read that some AutoMeter gauges are known to do the same thing.

 

[bison]

Thanks all for the responses -except for that brett joke-still cant believe they gave him away-idiot management

Mease down pipe-it boost great
I have turbo link and everything looks good blm etc
70 ctp bb turbo new-and 3200 lu convertor-stock longblock i can hold the brakes to about 2800-3000 rpm-then the wheels start turnen
no vac resovoir

So its actually a 2800-3000 stall. It needs a little more stall imo. Thats not the main problem though. You dont need a vac res. You apply and hold the brakes before boost is applied. There is a check valve correct? Verify the flapper is sealing and there are no exhaust leaks. If you have either it will suck balls trying to spool since the converter is borderline not enough already. Do the brakes seem ok when stopping? Ive had the rear brakes and drums glazed up pretty bad myself. It didnt help holding boost.

 

[GBGN1]

when you say check valve do you mean the proportioning valve for the brakes or the small canister type piece in the vacuum line?Ive got a straight hose running from the vacumm pod to the brake booster.Brakes stop the car good-i up graded to the front s10 blazer set up which i like and have aluminum bake drums on the car with longer shoes,brake cylinders ,nittos-no glave on the drums i just tolk care of that.Will look at exhaust again but boost(i need heads really bad) and runs really well.
I want to race in two weeks need to figure this out
thanks all!

 

[SGRIM]

If it is spinning the tires that quick you don't have an exhuast leak...

I would check your lines and P valve...

Sounds like you have the package, I am thinking you need more pressure to the back....

 

[Just a Six??]

when you say check valve do you mean the proportioning valve for the brakes or the small canister type piece in the vacuum line?
Ive got a straight hose running from the vacumm pod to the brake booster. thanks all!

Why no checkvalve for the booster? You really should have one to hold air in the booster.

 

[84BuickGNYorkPA]

Are you pushing through the lights like the brakes are not holding or does the engine not build boost on the line?

Chuck

 

[GBGN1]

pushing through lights-yes--------ill look into getting a check valve for it-u can get them anywhere right?

 

[84BuickGNYorkPA]

Got the s10 rear cylinders,long shoes on booth side and 275-60-15 nittos on the rear and the brakes are adjusted tight but i still cant hold it down at the line-I have vacuum brakes also.any more secrets i havent heard about -Even with the ebrake on i can only get maybe a pound of boost
thanks
Brian
1987 we4

I've been having the same problem, make sure all the basic's are covered, good bleeding of the lines, inspect all 4 corners and make sure everything looks ok visually(pull the rear drums), line lock helps keep the heat out of the shoes. Strong vacuum at idle helps, put the car in neutral right before the staging at the tree, give it a little rev while on the brake pedal, you will feel it go toward the floor a 1/4" or so, then pull the shifter back to drive and with your foot on the brake bring the rpm up to stage the car. Then while still on the brake push down as hard as you can and bring the car rpm's up to stage the 2nd light...... the trick is not to let the car move at this point... I have low vacuum pressure, hoping that the fresh motor helps me. Some have had success going to hydraboost set-up (84,85 stock brake system, that runs off the power steering pump)

Chuck

 

[GBGN1]

Any more suggestions?looken for a checkvalve any part # anyone?

 

[JST A 6]

Any more suggestions?looken for a checkvalve any part # anyone?

Your auto parts store probably has them in the "Help!" parts section. Most people don't even know what it looks like--it's the 90 degree plastic fitting that the vacuum line connects to, and it attaches to the brake booster through a grommet. You can check it by removing it from the car and trying to blow through it both ways--if you can only blow through it one way it's good. It's probably cheap enough that it wouldn't hurt to replace it anyway.

 

[GNRick]

I have a thread on this subject too. Is it possible to have too much vacuum? I installed Kirban's longer brake shoes in the rear along with new S-10 cylinders. I can hold up to 3400 rpm then car starts to move. A little more rpm's and tires squeal. I have no boost. I checked this with two different gauges. The second gauge has vacuum and boost. I noticed that I have 20 on the vacuum side. Needle has a long way to go to get to the boost side. Could my cam be too small? As rpm's rise, needle moves to boost side but doesn't quite get past 1 or 2 psi before the tires break free. I'm thinking I should start with less vacuum. Any thoughts?