whats the gain with that???

 

Because you don't need vacuum to work it.

Which comes in REAL handy when you're running boost, or a HUGE cam.

 

i have a CC 07-503-8 cam 224 230 503 510 lift 112lsa with a vacuum canister and vacuum is poor at idle i have to stay in gear to have power brake. would that brake more than stock vacuum master ???

 

That's nowhere near enough cam to cause vacuum problems.

Check your ignition timing, AFTER you make sure your timing mark is accurate.

 

since the lt1 dont have timming mark...i set the engine to TDC mark the pulley and flywheel in case the damper ever rotate... and add 6 degrees to 0 mark i have done.

that mean i dont have enough advance??? how else can i know?

 

Advance it some more and see what happens.

Better? Advance it some more. Worse? Back it off. Repeat until no further improvement is obtained. If you don't like it, put it back.

"Better" is up to YOU. How does it run? Does it spark knock? Start up easily? Gas mileage improve? etc. It doesn't whup out a timing light and think, "book says I'm supposed to be a 6° BTC but light says I'm at 7°, I'm going to run bad". Give the engine what it wants. If it RUNS good, it IS good.

Just a car. Not rocket science. Try it and see what happens. Beats the crap out of changing master cylinders, if that's all it wants.