being 72 years of age,all of my hot rods(close to 12-15 early Ford v8) always have a vacuum gauge for me to observe while driving my cars. They are forever moving each time the go pedal is changed. I have had this deteriorated guide many years and have consulted it many times. Pictured are 16 different readings showing various problems or statements regarding virtually any gasoline engines. A vacuum gauge will tell you many things about your engine. Enjoy—-Flatheads Forever!
I set carbs and timing by vacuum gauge any time I'm working on a non-stock setup. Factory settings will get you close but a vacuum gauge will put you on the money.
It’s one tool I use quite a bit, but most modern “ technicians” have no clue how easy and versatile this simple tool is to help diagnose issues. rhanks for sharing
My dad showed me how to set the timing using a vacuum gauge when I about 12. He said that way the motor would tell you what it likes. We would do a hands on test for prospective new mechanic hires one of the challenges was a plugged cat convertor where we would put a washer in the exhaust system . Hooking up a vacuum gauge would show really low readings , but some applicants did not even know how to use one . They wanted to hook up a scan tool.
We still teach it here for diagnostics however it’s getting harder to find a spot to hook one up as well Sent from my iPhone using H.A.M.B.
I have been messing with this some lately on a new engine with an aftermarket high lift cam. Hot Rod Magazine recently had an article on using a vacuum gauge and I was using that article as a guide. I tried working with the idle screws but the vacuum readings on this engine are erratic and it is difficult to see the change when you are adjusting the idle screws. I have been battling other issue lately but I plan to get back to the vacuum gauge and tuning soon. I would like to know more about how a non stock camshaft effects the vacuum readings.
The short answer is to restrict the line until the needle smooths out. That doesn't help you on the effects of erratic vacuum on vacuum advance units etc. I'm sure the more advanced guys here will have a ton more info on this subject
Neat...thanks for posting.....think that's the other gauge next to the Sun tach that was in the "paper route" 1955 Stude - you can't see the door but its right behind the rear bumper....also use these as well.........
Used to be a vacuum gauge guide like that in the front of every Motors Manual. One of my favorite diagnostic tools.
I am 76, and have been using a vacuum gauge in all my cars and boats, since my first car at 15 yoa. I also have one in my main tool box for tune ups. I wouldn't be without one. Bob
I remember those charts well and used them a lot. I had my first car (65 Cutl*** 330) my parents bought me a tune up tool kit from Sears or somewhere. The problem was that the vacuum reading was always low compared to what the chart said it should be. "A" is where it should be 17-21 in. My 330 was always about 15" or as is "C". And what does "C" say about that reading? Worn rings!! Now I was all worried that my engine was junk and worn out. Later me and a buddy checked other cars and they all were about 15". I remember telling my Dad that my engine was worn out and needed a overhaul... That went over well and of course I was wrong. Maybe that cheap kit had a bad vacuum gauge...
I never drive any of my old cars without a vacuum gage in my tool kit. It's been a help on more than one occasion.
The Jalopy Journal
