Choosing a Vacuum Gauge

MX3ak · Post by **MX3ak** » August 24th, 2007, 1:56 pm

Should a vacuum gauge for the K8 be measured between 0-70Hg or else 0-30Hg ?

Tunes67 · Post by **Tunes67** » August 24th, 2007, 2:54 pm

This is the one I am using.. full sweep 30Hg CF gauge..

Click Here

Tunes67

MX3ak · Post by **MX3ak** » August 24th, 2007, 3:23 pm

Thanks

The weird one I found was this:

Does it makes any difference if it's plugged near the throtlebody or at cruisedrive nipple?

Tunes67 · Post by **Tunes67** » August 24th, 2007, 3:34 pm

Would be better at the throttle body.. this way its measuring the overall vacuum of all 6 cylinders.. the nipple for the cruise would probably be ok though.. its fairly close to the middle of the intake as well. I have mine going off the throttle body. The gauge will come with a rubber "T" fitting and nylon tubing.. very easy to hook up.

As for that 70Hg gauge.. thats got to be for a big diesel engine.. at least thats my guess LOL

Tunes67

MX3ak · Post by **MX3ak** » August 24th, 2007, 3:45 pm

Well I notice in the meanwhile that they are able for same preasure.

Number 70 is just for the metric system.

Cheers

Tunes67 · Post by **Tunes67** » August 24th, 2007, 3:50 pm

No.. Vacuum is always measured in Hg which is "Inches of Mercury" Doesnt have anything to do with metric or standard. Since that gauge measures a vacuum upto 76 Hg (inches of mercury) the engine that could produce such a powerful vacuum would have to be large.. like a semi truck diesel engine. And believe it or not.. there are people that race those trucks.. so it wouldnt be all that unusual to find a vacuum gauge for such a application

Tunes67

MX3ak · Post by **MX3ak** » August 24th, 2007, 4:07 pm

No no... not in theis case!

take a closer look

there's ( cm Hg ) on mine and ( in Hg ) on yours

thats centimeters on one side and inches on the other. "Hg" maybe is for something like hydro gravity, or some Einstein stuff

but, yeah.. those trucks got to suck air like no other vacuum cleaner on earth lol

Tunes67 · Post by **Tunes67** » August 24th, 2007, 4:22 pm

Your right.. that gauge does measure in centimeters of mercury (Hg is the atomic symbol of mercury - Dunno why.. you'd think it would have an M in it somewhere).

I have never seen a gauge that measures in centimeters of mercury before.. weird. But ok.. I wouldnt know what to tell you on how it should read though LOL If you have a In Hg gauge.. you should be riding at 18 in Hg at idle with no needle fluctuation

Needle fluctuation will be a indicator that you have one or more valves not seating/sealing properly.

Tunes67

MX3ak · Post by **MX3ak** » August 24th, 2007, 4:48 pm

Yeah I found this gauge would be a good health indicator for the motor.

Allready got this picture document for reading the gauge:

http://www.classictruckshop.com/clubs/e ... ac/uum.htm

And yeah... I'm willling to buy one of those inches scale so we can discuss numbers more easily

Tunes67 · Post by **Tunes67** » August 24th, 2007, 5:14 pm

That little gem of a webpage should be in the FAQ section.. excellent diagnostic information and the exact reason I run a Vacuum gauge to begin with

Tunes67