Injection Port

[vng21092]

Whats the best way of turning a hole that goes through 2 layers of pvc pipe into a fuel injection port? the hole is around 1/4 inch in diameter
For visual: http://imgur.com/wMbwDRx

[PeteS]

Drill it out with a an 11/32" or 23/64" drill bit and tap it for 1/4 pipe and then use whatever 1/4 pipe fittings suit you?

[vng21092]

hmm but how would i secure it?

[PeteS]

hmm but how would i secure it?

Can you be more specific exactly what you are trying to do. Are you using a syringe? Trying to set up metered propane? something else? There are a ton of possible options for how to go with this.

If using a syringe, one way that has worked well for me is to use a presta valve (the skinny ones) from a bike inner tube and a 100 ml syringe with a presta to schrader adapter epoxied in. I solder or epoxy the presta valve into some kind of 1/4 pipe fitting. A cap with a hole drilled in it works as does a drilled out hose barb.

[jackssmirkingrevenge]

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I just use a small self-tapping wood screw for this one.

[vng21092]

The syringe thing was exactly what I was going for, thanks a lot. @JSR, would the wood screw ever pop out when firing?

[jackssmirkingrevenge]

Let's do the math, say your wood screw is 1/4" in diameter, and the peak pressure of the combustion is 150 psi. The force on the screw at peak pressure would be around 7 lbs. Take a screw you want to use, tap it into a piece of PVC and hang a 10 lb weight from it. If it doesn't come off, you're pretty much golden. This is a worst case scenario, peak pressure will most likely be much lower and you can find smaller diameter screws.

[jimmy101]

You can also use a standard tire stem (from a car tire). A rubber stem costs a buck or so, a nice metal one perhaps $2. Get a stem removal tool and permanently remove the stem and just close the port with the screw on cap. Tire Stems are installed from inside the chamber.


center bttom is a rubber tire stem, its stem/core, cap and the removal tool.


Shiny thing upper left of the chamber is a fancy chrome truck tire stem with a chrome cap.