You've added an LPR to your Impulse, but aren't you a bit curious to know exactly what the drastically lowered pressure rating to solenoid is now? It's not essential but some of us like to know exactly where we stand when tweeking things. There are a few different ways to add a gauge to your Imp and I will show you how to in this article.
Where To Add The Gauge
The most convenient spot to install the gauge is directly in the end of the pressure channel that goes through the right side of your Imp. This air channel provides pressure to the solenoid from the main front pressure chamber. The threaded end on the channel is at the rear of the body just to the right of the on/off button. There's a set screw plug that needs to be removed with a 3/16" allen wrench just like you did on the front of the body when you installed the LPR nipple. You'll need to apply a little heat the body in that area with a heat gun or similar to loosen up the loctite before it will even start to budge. It may be a bit difficult at times to remove but with some patience and perseverance it will eventually give. I would suggest removing the noid tray and trigger frame assembly before doing this and be careful not to pull the wires from the solenoid in the process
Ways To Attach The Gauge
You will need a 0-300psi or less pressure gauge for this add-on. A micro or mini-gauge is your best preference of size. There are several ways to attach the gauge and I will submit all that I'm familiar with.
1) The most simple manner is to just screw the gauge directly into the threads of the channel end. You will need the longer necked gauges available from Smart Parts to do so. The normal shorter versions available will not fit because the end of the ram housing sticks out the back of the body and gets in the way of screwing the gauge in. You will need to brush on some liquid teflon or wrap a few layers of teflon tape around the threads of the gauge to ensure a proper seal. The downfall of adding the gauge in this manner is you will need to remove the gauge every time you want to remove the ram housing to clean and lubricate it. Effective but not too practical.
2) Another way to add the gauge is to screw a 90* or 45* 1/8"npt elbow at the end of the channel clocked in a 4 or 5 o'clock position then screw the gauge into the female threaded opening of the elbow. The gauge after installed will be facing the right side of the marker not directly at you. This a bit more practical than just screwing the gauge directly in the threads because the ram housing can still be removed for cleaning without having to remove everything. You will need to brush on some liquid teflon or wrap a few layers of teflon tape around the threads of the gauge and elbow as well to ensure a proper seal.
3) You can screw the 1/8"npt threads of the male portion of a quick disconnect into the end of the air channel then screw the gauge into the female portion of the assembly. When removing the ram housing you can simply disconnect the gauge portion of the assembly to get it out of the way. This of course would need to be done while the Imp was not gassed up. The only drawback of attaching the gauge in this manner is if you don't have the 2 pieces of the q/d assembly properly connected to each other, the gauge could pop off in your face while gassed up. As long as you have the 2 components properly attached, there should be no danger at all. Of course you will need to brush on some liquid teflon or wrap a few layers of teflon tape around the threads of the gauge and quick disconnect as well to ensure a proper seal.
4) The most practical way of attaching a gauge to the back of your Imp is not attaching one at all. Instead go to your local ACO, Home Depot, Lowe's or hardware store and purchase a 1/8"npt Brady Schrader air valve used as an air inlet for water systems or other applications. It looks like a shortened version of an air valve for tire rims or inner tubes with a plastic cap attached. I have provided a photograph at the top of this page as reference. Simply screw it into the end of the channel using some liquid teflon or wrap a few layers of teflon tape around the threads to ensure a proper seal. This small item should cost you all of $2. What does this do you say? Now all you need is to invest in an inexpensive 0-99psi digital tire gauge that should cost you $10 or less. When you want to know what the pressure is you can simply push the digital gauge on the valve of the Schrader air valve and it will tell you exactly what the pressure going to the solenoid is. Be sure to get the 0-99psi gauge and not one of a lesser maximum pressure. The reading will be much more accurate than using the mechanical readout mini gauges and most likely cost a bit less as well with a total investment of approximately $12. The only drawback of this is that you cannot continually monitor the pressure setting while shooting your Imp to see any fluxuations in pressure. There are some fancy custom caps you can get for bicycle and car applications to screw on and hang off the back of your Impulse as well.
Technical Information
