vacuum gauge bounceing

[mmurffy03]

i have a new harbor frieght vacuum guage but any manifold port i hook it up too dosent have a steady reading bounces back and forth but i looked and havent found any vacuum leaks and just changed my intake o rings and have #6 plugged due to using a pingle ?

[Joe Hummer]

you have to put a valve in line with the gauge to even out those pulses.  Here is my Vacuum setup...


That black knob is to a needle valve that takes out the pulses. 

Joe

[fudgie]

You can get a needle valve at any hardware. They are usually brass. This will eliminate the bouncing. Just tighten it till it stops bouncing.

[Patrick]

I guess these gauges no longer come with a damper screw, so, you just make/add one.. All you have to do is pinch the line enough to reduce the pulsations until they are just barely noticeable.. A small clamp such as forceps will work or as mentioned an aquarium valve.. I put a 'T' in a length of vacuum line from the gauge to #3.. All the other lines go to the rear of the engine and they get plugged[ golf T] until needed.. Just plug one line into the 'T' , clamp[forceps] it off and read #3, move the clamp to #3 line and read and adjust that cylinder to match #3.. Repeat, and in a few minutes they are all within 1/4 to 1/2 in/hg.. Its easy to forget to clamp off a line and read 2 cylinders at a time, but, you'll figure that out.. Hondas spec is 1.6 in/hg, so, the single vacuum gauge is cheap, simple, fast, and as or more  accurate than as needed.. Make sure the engine speed stays pretty much the same throughout this and you should be happy with the outcome.. It actually took longer to type this than to do the job..

[whitestroke]

I use 6 gauges and bought Rainbird (sprinkler) valves at Ace hardware.  Cost about $12. for 10 valves or so. they work great

[Misfit]

Instead of buying valves I used couplers/splice. I plugged one end of the splice with J B weld. After the J B set up I drilled a very small hole in the J B plug. Cut your vac hose into and add the coupler/ splice. Instant snubber.