my boost/vacuum gauge, are my readings bad?

[Foxfan88]

ok my car will make less than 10 inches of vacuum at idle. alot of times it makes a steady 10 inches at idle but sometimes its lower. upon moderate acceleration ( not making boost) it will stay at around zero and if i let off of it it will pull 20 inches of vacuum.

is there anything to be concerned about. it seems like it should have more vaccum. my brakes work pretty good. sometimes they may get stiff on me but not often. does my SC affect vacuum readings?

and there isnt any audible leaks, i will check some hoses and see if i can find any. would a leaking intake make a sound? also i looked on a site and it said it could be late valve timing. not sure what this means, but my b-cam is 4 degrees advanced so it messes with the valve timing could this be it?

 

[enyawix]

No idea my NA 351 pulls 12 to 14

I am swapping parts off my 347 to a 351, so it is not running

 

[BLOWN 5.0 FOX]

are you going directly to the intake or are you Ting off??? I was having issues with my boost gauge until a local shop told me to run boost gauges to intake only. Anywhere else runs the risk of "sharing" pressure.

 

[88mouse]

the cam advanced will mess with it some.

 

[bretamo]

Mine's around 18 at idle, and I tap into a port off the vacuum tree next to the brake booster.

 

[Foxfan88]

my gauge Ts into a vac line. my FMU line is plugged into the spare vac tree nipple and i just T into that shortly after and it runs into the firewall

 

[Skoobie]

Its hard to give a definitive answer on that. Stock merc is 18-21hg. Depending on your setup that can vary wildly. Does it idle ok? Any surging? Mine sits at 12.5 hg and Im pretty sure I have a leak somewhere because my idle is not stable at all. Unfortunately its not an audible leak and so far a check of all the visable lines comes up with nothing. I need to pull my fender well cover and check the vac canister. Anyhoo my buddy has a novi 1000 and he pulls 16-17 hg so I dont think its your charger causing the problem. I would just double check for intake/tb leaks and go over all your lines again. Remember you have vac lines under your dash as well. Check those too.