Quote:
Originally Posted by 3r!c84
 yea that little ball !! haha damn there went that idea. the other idea was on my stock 305 it had like a check valve looking thing on the line from the carb to the booster. do i need that? im just running a rubber line to carb to booster |
There absolutely needs to be a one-way check valve somewhere... either in the hose between the intake manifold and the brake booster, or sometimes they are built into the inlet of the brake booster itself.
A quick test:
1 - start engine and let idle
2 - press brake pedal sharply and listen for a 'hiss' sound. That sound indicates you have some vacuum
3 - release brake and let engine continue to idle for a few seconds
4 - shut off engine and wait 10 seconds or so
5 - repeat step 2. If the system is working properly, you should still hear the same hiss sound. If you do not, then the system is not holding vacuum. Either the check valve is bad or missing, or the diaphram in the booster is ruptured or leaking. You should get at least 2 or 3 brake pedal pushes with vacuum boost assist before all the vacuum is blead away with the engine not running.
Back to the earlier discussion on the vacuum can. If you are going to add one, it would need to be on the booster side of the one-way check valve. The vacuum can only adds extra 'capacity' to the vacuum system. It does not in any way generate more vacuum. All it can do is hold highest vacuum the engine can generate.