Vacuum gauge help


solid fixture here in the forum
Staff member
Can someone please advise me on a vacuum gauge. Just a reliable, easy to find and reasonably priced vacuum gauge. I need to know the best connection location for timing, diagnostic testing and any attachments/hardware needed for using on a stock small block Chevy.

Thank you,
I got mine at harbor freight for about $19, and it works fine, sears sells the same gauge for a few dollars more and similar gauges are available at advance auto
READ THRU THE LINKS ... 5887561009 ... 921x00003j ... gauges.cfm


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Great! Thanks Grumpy!
I don't know how I got to today without ever having one. Will the instructions be complete enough to show where to connect (properly connect) because I understand there are different pressures within the same system depending where your're connected? I'm puzzled why a perminantly mounted vacuum gauge is not a must have for most serious performance cars and trucks? Instead I see mostly temp and oil gauges.
heres a few links that might prove useful
youll find a hour or so reading thru the links and sub links, on this site in the threads, will provide a great wealth of related info and incite into related factors, or the function or testing of sensors, that you may not currently be thinking about, or things that you might not think that are related to your issue that PROBABLY ARE









Just what I was looking for! Tested vacuum today and it's low, about 12 in Hg vac.
Going to do another compression test tomorrow as well.

I'll read the links above.
Cool, so when my boost/vacuum gauge do fancy things on the dash it will help point to the problem. :)
Thanks. going to save that picture into my computer just in case loll.
that linked HF gauge may not be top quality but Ive had one for almost 15 years and amazingly it still works so its well worth the $10 I paid for it back then
Awesome, that's the one I picked up yesterday. I was wondering how accurate it was.
Tested for leaks with a little torch and didn't find any.
Honestly, I'm not real sure what kind of vacuum I should have.
12 just seems a tad low to me.
Going by the image, it looks like late valve timing, I sure hope not... Going to keep testing and reading.
I read that link last night. I have a buddy coming over at some point today to work the throttle for me.
Starts coming in approx. 1000-1200 rpm, I have 16 initial - 38 all in at approx 2800 rpm. Still reading how to accurately read the plugs as well. So far they look like it's rich or too cold of a plug.
I had no idea there's so much detail in reading plugs, can't believe I am just learning this... Going to grab a magnifying glass today so I can see the inside better.
I don't have power brakes or steering. I have one vacuum line to the tranny and one for the distributor which I have plugged at the moment.
I do need to get a new hose for my pcv, I think the po used a piece of a garden house to splice it...
Hard to hold the throttle steady at some RPM, I used the idle screw to set each level. Yours may not make all the way to max advance, but the idle screw is still better at the lower RPM's.

I did what you are planning, then I had palm slap on the forehead event !!! heheheh !!!

if your reading this and wondering about the plug reading? these links posted above,
will get you started and reading the SUB LINKS is MANDATORY, if you really want to learn
I spent a good 2+ hours reading last night and plan to read more. I would go into a link then sub links, then sub links in the sub links etc etc... it's a lot of reading but it's well worth it.
Hard to hold the throttle steady at some RPM, I used the idle screw to set each level. Yours may not make all the way to max advance, but the idle screw is still better at the lower RPM's.

I did what you are planning, then I had palm slap on the forehead event !!! heheheh !!!
Good idea, thank you! I will do that and see what I can come up with.
I just replaced all of my 2 hoses. The pcv hose had a big split in the end but the vacuum ended up the same.
Going to see if I can verify my advanced curve now.

Appreciate all of the links and advice, I feel like I've learned a lot but yet, still know so little...
I've been keeping a log of my changes so I am not just guessing at everything and forgetting anything I've already done.
Well I didn't get to find the curve yet. I wanted to triple check my tdc. So I made a piston stop from an old spark plug.
I cut off that little shoulder right next to the ceramic with a hacksaw and it basically just fell out.
I drilled it, tapped it and rounded off the bolt, then gingerly turned the crank till the piston kissed the bolt, both directions.

The notch is perfectly centered between my 2 gold dots there.

Did a compression test while I had the plugs out. All were 150 except #3 it was between 140 - 145
However, #2 is at 120... I doubt I have even put 100 miles on this yet, maybe #2 rings haven't fully seated?
I guess I'm not sure if I need to worry about that yet or not. Should I wet test it, or drive it a bit more and see what happens? Sounds risky when I say it like that...
Driver side plugs all look terrible, passenger side looks pretty decent. Almost all have oil on them...
Now that I have them all out I am going to study more on reading them.

I'm done for today, my garage faces west and it's hotter than hell out there.
Time to do some reading...
Apologies if I should have posted this elsewhere.
I'm far from pro, but I did check timing on all 8 about 2 weeks ago. I just put in a new distributor, my old hei was really old and falling a part, the pickup coil was all cracked and the wires were barely hanging by a thread. Then it shorted out because the wires from base to cap had been worn and were touching. I did rebuild it to have a spare though. It wasn't running great with that old hei.
I picked up a new set of plugs today as well.
Going to buy a leak down tester tomorrow as well. I've been buying tools for many years, too bad they all pertain to wood...
I like performing compression tests 1st.
Eliminates guess work.

Helps dictate what cam is installed too if unknown specs.