Vacuum in 5.0 at idle?

[Piston]

What kinda vacuum pressure should I expect at idle? At what point does low vacuum affect the brakes in a neagtive way? At 1200RPM's i was seeing 9lbs.

 

[Acid7711]

The engine load and throttle position play a big part in engine vacuum. I see about 18 inches (if not inches then whatever it is) at cruise in 5th, and about 20 at idle.

I could see that low number causing a problem, but I'm unsure how much vacuum the brake booster requires to fully opperate?

 

[HISSIN50]

Single digit vac can create issues with the power brake assist. There are some work-arounds for it, but it can be kind of a pain.

I see 19.5" hg at idle (670 RPM).

Good luck.

 

[Piston]

Single digit vac can create issues with the power brake assist. There are some work-arounds for it, but it can be kind of a pain.

I see 19.5" hg at idle (670 RPM).

Good luck.

What are the workarounds? The strange thing was my brakes used to work fine with this cam but then all the suddenly they don't. I didn't have a guage to see how much vac I had but I see about 10. I tried revving the car up and got like 15+ and the brakes didn't seem to change.

 

[HISSIN50]

If things used to work alright before, I'd look for an malfunctioning component (like a bad vacuum hose, etc).

Amongst the easier work arounds for the typical 'big cam' are a simple vacuum cannister/reservoir, or even a pump. The former can be pieced together for very cheap using J/Y stuff.

I'd still give things another once over since this is a new issue.

Good luck.

 

[Piston]

well i ordered a new brake booster hope that helps.

 

[VG30DE]

I see about 8-9 at idle, the brakes are just starting to get hard... I have just learned to downshift to get the vacuum up and I dont even notice...

 

[Piston]

I see about 8-9 at idle, the brakes are just starting to get hard... I have just learned to downshift to get the vacuum up and I dont even notice...

Yah that's not the problem for sure. But I know what you mean.