Anyone else notice that the Autometer vacuum gauge reads from right to left. I think it looks stupid. I can understand a dual boost/vacuum gauge having to read in both directions but why a vacuum gauge reading right to left? 
CK5
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Autometer vacuum gauge
- Thread starter 4X4HIGH
- Start date
The reason is does that is because vacuum is kind of a negative pressure, so a higher number is technically lower than 0. So when we move from 20 inHg to 15 inHg, pressure has increased, thus it moves to the right. True absolute 0 is 0 psi. What you are reading is actually gauge pressure, or psig (psi gauge), where 0 psig is 1 atmosphere (14.7 psi) above true zero. So the vacuum gauge is actually counting up from a negative pressure to zero.
It does look funny though, I agree. Kind of like the dB on stereo volume sometimes where it counts up from - 80 and increases to 0. It just seems counter intuitive, and looks odd, even though it's technically correct. If I am telling you something you already know then I apologize.
It does look funny though, I agree. Kind of like the dB on stereo volume sometimes where it counts up from - 80 and increases to 0. It just seems counter intuitive, and looks odd, even though it's technically correct. If I am telling you something you already know then I apologize.
anofzinger
Registered Member
What is a good pressure to have? I am trying to redo Edelbrock 600 CFM for high altitude. Currently showing between 7-9.
Vacuum reading should be between 17-21 hg. for an engine with a stock cam. The hotter the cam gets the less vacuum the engine will produce and the choppier the idle will be.
Are you sure you're checking your vacuum from a manifold vacuum source and not a ported source?
Are you sure you're checking your vacuum from a manifold vacuum source and not a ported source?
anofzinger
Registered Member
I removed the PCV Valve hose from the front center port. I then removed the vac line going to distributor. ( Looking at carb it was the port on the left) Truck runs super rough and has NO power. We will be removing carb, intake, dizzy and wires tomorrow. I don't know what cam was put in after motor was rebuilt. I was told it was 400+hp motor, but I have serious doubts. I think I was taken ( by a supposed friend)
anofzinger
Registered Member
What do you mean the "hotter" the cam gets?
wouldnt waste much time checkin the cam. real hard to tell what it is unless you have tools to ccheck the lift /duration stuff like that.
hotter cam. big lift high rpm use. not a low rpm friendly cam.
some cams have #'s stamped/ground in the end at the back of the block. but have to pull the cam for that.
and sorry to here you prob fell for the its a xxx hp motor with all the good stuff. when its prob a 305 125 hp with a flashy top end. i take no ones word for it.
hotter cam. big lift high rpm use. not a low rpm friendly cam.
some cams have #'s stamped/ground in the end at the back of the block. but have to pull the cam for that.
and sorry to here you prob fell for the its a xxx hp motor with all the good stuff. when its prob a 305 125 hp with a flashy top end. i take no ones word for it.
1BEATK5
1/2 ton status
Anyone else notice that the Autometer vacuum gauge reads from right to left. I think it looks stupid. I can understand a dual boost/vacuum gauge having to read in both directions but why a vacuum gauge reading right to left?
every aftermarket brand vacuum guage i have seen is like that
1BEATK5
1/2 ton status
wow. didnt see that coming. i have seen alot of them backwards though
i like the 3 color one best. if i was to buy one and use it that would be it.
Anyone else notice that the Autometer vacuum gauge reads from right to left. I think it looks stupid. I can understand a dual boost/vacuum gauge having to read in both directions but why a vacuum gauge reading right to left?
actually i can see it making sense.. idle - rpm - sweep.. at idle it's off to the left, rev it, it goes to the right, like a tach..
