TJefferson2020

Hey V8 - thanks! Although my set up is more street rod than stock - the stock config was helpful. I installed a T fitting and know the engine runs fine.

Still losing vac when plugged into brand new booster #2. I guess I'll go to #3. These things aren't cheap!

Would it matter that I have no master cyl installed?

pm

TJefferson2020

I'm at my wits end with my power brake install. Here's the set-up:

1970 LT1 modified, running off the rear of the carb into a vac reservior tank (aggressive cam - need tank to store vacuum) - hose from the tank to the power booster check valve. Vac gauge on tank.

Issues:

1. When I plug the hose to the booster with my finger, I make plenty of vac - over 15 inches - however, engine runs badly at idle
2. When I plug into the check valve on booster, vac hardly reaches 10 - at idle it's 5 - and engien runs rough.
3. When I shut down engine, all vac goes away instantly. It's leaking out through the booster check valve - is this normal? It's the second booster I've received and it does the smae thing the last one did.

As far as running rough, I think it needs a T fitting from the carb (thanks, Lars) to draw air from the valve cover - Where can I get one of these?

Nothing seems to be leaking at the hose junctions it only happens with the booster hooked up.....Please Help!

PM

lostpatrolman

The booster check valve shuoldnt leak.

TJefferson2020

Thanks, Lost Patrol!

Just to be clear - the valve should let air out but not in. On the last booster the valve sucked air from the booster and did not let it back out. It seems like the vac is coming out somewhere inside the booster = If I remove the valve to test it I void the warranty but i did remove the valve on the first one and it seems fine - is it possible to be leaking inside the booster?

V8yunkie

Plug the line between tank and carb completely - if engine runs OK then, the leak in the booster is too bad. Replace booster as internal damage of diaphragm most likely.

Vacuum line from rear of carb should go directly to booster.
Tank is supposed to be connected to fitting on intake manifold (close to distributor). After fitting, first comes white filter, then silver checkvalve. Thick line (power vacuum) from this to tank, thin line (control vacuum) through firewall to interior of car.

Separate vaccum port from carb should run to one PCV-valve on valve cover. From other valve cover, line should run to airfilter. Or breather on other valve cover.

This is the normal setup.

Regards,
Thomas


[Modified by V8yunkie, 4:56 AM 3/22/2004]