testing jets

[1930artdeco]

I would like to test some jets and then adjust if need be. Would someone be willing to post pics of their flow tester? This way I can figure out how to build one. Also what is the best way to solder/seal and redrill the jets? I would like to find a way to fill the whole jet and then redrill if possible. If not I will just have to fill in the bottom and redrill it.

Thanks,

Mike

[160B]

Here is the one I built. 36" from centerline of overflow to centerline of test port. Valve is to throttle the pump flow. Do not use an elbow at the top for overflow unless you drill it at the top to vent the column. This is necessary as the syphon action of the overflow can reduce the column pressure.

[Bob Johnson]

Here is one I built. It is easy to build and does not need a pump, valves ... Since the water reservoir at the top is large the water level does not drop enough during a test to make any measurable difference in the results. Plus you can set the water level to whatever height you want.

Bob

[Tom Endy]

Go on line to www.ocmafc.com (the web site of the Orange County Model A Ford Club of Southern California). On the menu at left scroll down to "tech articles" and click. It will bring up a new menu. Click on my name at the top (Tom Endy) and it will bring up a series of articles. They are all adobe files and you are welcome to download and use any of them.

Scroll to the one on Zenith restoration. There are a number of photos of a flow tester along with the specs for the jets.

Tom Endy

[redmodelt]

You do not have to fill the whole jet, just the tip where the hole is. you will never drill a straight line if you fill the whole jet anyway and it would take too much effort for the fuel to be sucked through that long tiny hole.

[Bluebell]

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Yes, the rate of flow through a jet is dictated by two things;
1. the diameter of hole, and
2. the length of the hole.

[redmodelt]

RE: 2. the length of the hole.
Please expand on that in relationship to the jets in a Model A carburetor.

[160B]

Originally Posted by redmodelt

RE: 2. the length of the hole.
Please expand on that in relationship to the jets in a Model A carburetor.

Original jets are a certain length, but the inside diameter is not the same over the entire length.

At the tip of the jet there is an orifice, smaller diameter sized to deliver the correct amount of fluid. This orifice is say 1/32” long at say a # 63 drill size.

Now when you solder the tip closed you cannot control the amount of solder that flows into the tip of the jet. So let’s say after soldering you now have to drill a # 63 size hole through let’s say 3/32” length of solder. This jet now has the same size orifice of # 63 drill but since the orifice is now 3/32" long the flow will be reduced.

Also the entrance into the orifice is not the same gentle curve due to the results of soldering, so this will also reduce the flow because you have changed the entrance characteristics of the orifice.

I will upload photos when I resolve a missing security token that does not allow me to upload photos

[Mike V. Florida]

Originally Posted by 160B

I will upload photos when I resolve a missing security token that does not allow me to upload photos

Ryan wrote this a few years ago;
Are you getting a "Security Token Error?"
If so, please excuse it... It's a bug. Typically you get that error when uploading images. It just means that the images you are uploading are too large in file size.

[160B]

Originally Posted by 160B

Original jets are a certain length, but the inside diameter is not the same over the entire length.

At the tip of the jet there is an orifice, smaller diameter sized to deliver the correct amount of fluid. This orifice is say 1/32” long at say a # 63 drill size.

Now when you solder the tip closed you cannot control the amount of solder that flows into the tip of the jet. So let’s say after soldering you now have to drill a # 63 size hole through let’s say 3/32” length of solder. This jet now has the same size orifice of # 63 drill but since the orifice is now 3/32" long the flow will be reduced.

Also the entrance into the orifice is not the same gentle curve due to the results of soldering, so this will also reduce the flow because you have changed the entrance characteristics of the orifice.

I will upload photos when I resolve a missing security token that does not allow me to upload photos

Thanks for the input Mike V. Florida


Original jets



Soldered jets

[Pinstripe]

Excellent information Thanks

[Sparky]

Here's my tester. It's hard to se on the picture but there is a submersible pump in the water reservoir. There is a smaller supply tank inside the large one that supplies the water to the jets. The pump keeps the level of the water in the supply reservoir constant; the excess water overflows into the catch tank and gets recirculated.