I got a cheap 15 dollar Sunpro Vacuum guage from Pep Boys the other day.. this thing is great. Mountable, lightable and it works.

Anyway, I read a steady 16 PSI at warm idle, which is low, I'm shooting for 20. But. I have a pretty bad exhaust leak coming from my exhaust manifolds, will this cause it to be low? I don't want to have to take my intake off to fix all these lines all over again and do it right but if thats what it takes than I'll do it in a heartbeat.

Thanks.

 

im not completely sure but i doubt that an exaughst leak would cause you to have a low number like 16 inches of vacume

 

Well, I -do- know that it will cause it to be out of wack... just not sure if a leak will make it low...

 

I think it should be somewhere around 27.
But I doubt an exhaust leak would contrbute to low numbers.

Unless the leak is a bad EGR valve which the you could lose vacuum.

 

No, it's not supposed to be 27.

I found what I was looking for... it's supposed to be somewhere in the 17-22Hg range... so I'm a little low.

I'm willing to bet my timing is off and/or I have leaks... as soon as I get this b*tch mounted I'll tune with it... :-D

Thanks anyway guys...

 

ok guys ,

to start with sunpro gauges arent all that bad...
(u can buy 2 of these maybe 3 for the price of one autometer gauge)
i ahve 2 of them sitting in my autometer gaugepod..

one happens to be a vacuum gauge
.

ok normal reading for a idle @750-1000 rpm is around 18Hg

when in idle u accelrate .. and leave it it should hit 25 at max

if ur givin it a hard accel during driving it should go down to zero

...

ok ur 16 might be cos of two things...
- u should connect iit to a pure vacuum source ... and not on the brake booster side ..or anywhere else..
- u might have a leak in a line somewhere ... put ur ear close to the gauge and if u hear a hiss ... the size of tube isnt right
i think i used 5/16 im not sure though...

its been working great for 6 months now ....

 

and xeno by the way where didya hook that thing up... its got nothing to do with ur exhaust headers
u dont have to take ur intake headers off also....

behind ur intake header towards the wiper motor there is a brake booster linre that goes to a junction in the intake manifold and that also splits ina T and another line goes to the vacuum canister ... u can cut the line that is not the brake booster line and splice it Put a T junction in it ... get some tubing and T Junc from autozone and hook that thing up

 

There is a connection at the back of the intake manifold, it tees off... one side goes to a brake booster, the other side is a smaller line that connects to a reducer/splitter thing (the part that tees off of that goes to a wire harness type deal) and the continuation of that runs down to the vac canister/purge solenoid... I hooked it to this smaller line before the restrcter..

The reason why I said I was going to take my intake manifold off is because that whole plastic PVC system back there was shot.... it was kinked up so I replaced it with some heater hose and some synch-ties.... I was going to take it off to have a clear shot down there to do it right...

I'm pretty sure it's my timing or a vacuum leak... it's raining/snowing here so it's going to have to wait for warmer weather...

thanks guys!

 

Thanks for correcting me on this. I was going buy the readings that our small block chevy racing engines produced . The cam and compression must change the numbers a little.