I have a 94 firebird with the lt1 in it and was wondering if anyone knew how much vacuum it should have? We done a vacuum test on the intake and it was around 16 inches, is rthat right? When we snapped the throttle it went to zero up to 25 and then back to 16. Any help greatly appreciated. Thanks

 

It should be closer to 20", in stock form.

 

16" isn't too bad on an old motor, but yeah, close to 20" is what they had new

so, check for vacuum leaks, but don't be too worried if you don't find any

 

It's a rebuilt motor, it was done in sept 06, it had rough idle and running rich since we got it back but it ran fine before the rebuild, it got new plugs, wires, injectors,coil, opti, and egr. It also surges at low rpm, oh also a new icm, even the engine builder can't figure it out, just alot of guesses.

 

is the vacuum steady at idle?

stock cam or?

 

Stock cam and pretty steady at idle, it vibrates between 16 and 17 inches thanks

 

Are the valves adjusted correctly? Too tight will cause rough idle and low vacuum (yours is not too awful low, though).

I get about that much vacuum with my mildly cammed engine.

 

i get 12 in HG on my setup and the brakes still work fine..... typically 16-20 is considered good. bret bauer says i should get more vaccum with my setup, but i can't find any leaks and the engine is healthy. ??

 

iwillcheckintothatthanks

 

Hijack