Vacuum Test Gauge

Ok professional mechanic types......what brand of vacuum test gauge should I be looking at? Wanna check some things on my 231. Thanks

 

Fuel Pump and Vacuum Tester

Amazon.com: 8milelake Fuel Pump & Vacuum Tester Gauge Leak Carburetor Pressure Diagnostics: Home Improvement

They are such simple gauges unless your a Pro spending much money on one is a bit of a waste.

You could also go to ebay and buy a used SW vacuum gauge in 2" or 2 5/8"

 

Mine is a actron Works very well.This thing is amazing. Will tell you a lot about a motor.

 

I have a $15 Lisle one that works great.

 

My Harbor Fight one works great

 

I have this ATD gauge - Amazon.com: ATD Tools 5657 Deluxe Vacuum/Fuel Pump Tester Kit: Automotive - seems fine, though I have not used it a lot. Nice thing about this is the gauge face is large, so small needle movements are easy to see. Considering the couple of recent negative reviews, I might pick the Harbor Freight gauge today. Or the Acton. But my ATD works fine.

 

Reading reviews on several different brands. It seems any and all can have inaccuracy problems....the needle not resting at 0. Can it be adjusted/calibrated on all brands or just some brands? Looks like they are ALL made in China so, no way around that I guess.

I like the larger gauges and the ones with a hook to hang them from somewhere. Still undecided on which to get. Maybe I'll check the local stores and see what's available.

 

So, I went out to the garage, to the tool box, and opened the "tune-up" drawer and dug around a bit. In the back of the drawer I came across this little gem. Kinda remembered having it but wasn't sure.

As you can see, it reads about 1.5 lower than the mighty-vac I used to test it. This assumes the Mighty-Vac is indeed accurate. I took the bezel off of the gauge and loosened the two brass screws on the back of the vacuum gauge, in an attempt to adjust the gauge but, no luck. I'm either to dumb to make the adjustment or there is no adjustment there. ????

So, in the pic below, do I remove one of the plugs in the intake and install a barbed fitting, to hook the vacuum gauge to? Or can I use the rubber line between the carb and the PCV valve?

 

Install a tee in the line to the carb to hook up the gauge up to then remove it when done. You can get vacuum line fittings at your local auto store.

 

The PCV line? Not sure if the valve would mess with the readings or not. Sorry for asking dumb questions.

 

Where does the vacuum advance for your distributor connect? That can be either manifold vacuum or "ported" vacuum. The only difference is that ported goes to zero at idle, and is identical to manifold otherwise. Ported vacuum always comes from the base of your carburetor, but not every carburetor vacuum port is ported vacuum. Tee into the distributor line and look at your vacuum readings. It should be easy to tell the difference between manifold and ported.

If you have no manifold vacuum port, remove one of the plugs in your intake manifold and replace it with a suitable brass barbed fitting (any hardware store will have this). Then use that port for testing, and cover it with a vacuum cap when finished.

You can use the PCV line for testing - just tee into it near the carburetor - but I would install a fitting and then have a test port always available. In either case, you will have to cap the tee. Keep an eye on the caps and plastic fittings - the material these are made from is rather poor, and they will deteriorate with age. Vinyl caps are best for vacuum, if you can find them.

 

x2 on the large dial. 3-1/2" to 4" makes it much easier to read.

 

I plugged my gauge into the PCV line with a tee. Got a very low 8.5 reading. I've since found another gauge in one of the storage garages, which is in a kit with a timing light. I am going to check it with the second gauge and then probably put the timing light on it. I've got an issue somewhere. Gotta check for a vacuum leak too. Just haven't gotten to it yet.

I think I set the timing by ear many moons ago (though, not THAT many miles ago) so, I won't be a bit surprised to find the timing off. Don't know if I ever actually put a light on it or not. Young and dumb.

 

Figured I would throw my 2 cents out there even if I am a little late. I have the OTC gauge which does vacuum and fuel pressure. Comes in a nice case with a few fittings and the gauge itself is large and easy to read. Little more than some of the options above but I trust OTC more than most low priced brands and with measurement tools I have to be able to trust them. Link to the amazon page. Amazon.com: OTC 5613 Vacuum/Pressure Gauge Kit: Automotive

 

I also use the actron cheapie. Here is a great link for how to read one.
Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine