How to: Jet flow test?

[TDO]

The set up I use is basically like the one in # 18 using the 36" column. When I got my flow tested jets from Renner's I tested them on my set up, And got the same reading that Renner's got.

[160B]

Originally Posted by Mike V. Florida

if you push the water past the outlet, I would think there would be added pressure to the outlet as opposed to water supplied from a different pipe and flows over the the tube with the outlet?

Originally Posted by 160B

here is the set up I have, it has a submersible pump in the pail feeding the bottom of the column. The centerline to centerline distance from the overflow to the test port is 36 inches

In looking at the diagram in post #39 by Mike V, there is an important element in constructing your water column in that the top of the column "MUST" be vented or the overflow will create a syphon effect and you will not have the full pressure of a 36 inch water column.

Note that on the top of my test column there is a “T” that vents upward and provides a connection to the overflow tube. The 36 inch measurement is from the centerline of the overflow to the centerline of the test port.

[edmondclinton]

Originally Posted by RonC

Ed the flow rate is affected by the head or pressure of water at the jet outlet. Water has a weight (62.4 pounds per cubic feet) and the more depth of water the more weight. So yes if you change the amount of water (head) over the jet outlet the flow rate will change. The difference in rates based 36 or 37 1/4 is listed on Vince's site. You can calculate the exact flow rate one can expect based on the head used and jet outlet size and shape. I'm sure Ford calculated what they wanted for rates for their engine and instructed zenith to manufacture according to their specs. It doesn't matter what head you use in inches as long as you are using the expected flow rates derived from that head. Al Blatter tested flow rates of nos jets at a head of 36 inches based on his experience. He could have used any other head just his flow rates would be different. You need to stick to whatever head was used for water ever rate information you are comparing to.

Sounds good Ron. Was there something about my posts that lead you to believe that I did not already understand what you said above?

[Richard Lorenz]

I'm sure that everyone knows that the 36-inch height must be from the water level at the top to the tip of the jet (which might be different from where the flexible tubing comes out of the apparatus). If your apparatus provides the 36 inches and the tip of the jet is below where the flexible tube joins it, your reading will be too high. The reading will be too low if the tip of the jet is higher than 36-inch exit location.

I use an electronic scale to measure the amount of water flowed in one minute. It is safe to assume that 1 gram of water is equal to 1 ml or 1 cc of water. This method is much more accurate than what you can read with even with a chemist's graduated cylinder.

[edmondclinton]

Originally Posted by Richard Lorenz

I'm sure that everyone knows that the 36-inch height must be from the water level at the top to the tip of the jet (which might be different from where the flexible tubing comes out of the apparatus). If your apparatus provides the 36 inches and the tip of the jet is below where the flexible tube joins it, your reading will be too high. The reading will be too low if the tip of the jet is higher than 36-inch exit location.

I use an electronic scale to measure the amount of water flowed in one minute. It is safe to assume that 1 gram of water is equal to 1 ml or 1 cc of water. This method is much more accurate than what you can read with even with a chemist's graduated cylinder.

If it was required to get the flow to an exact individual number then I guess we'd all need an electronic scale. But, only to be within a "range" is required. A chemist's graduated cylinder is plenty accurate if one knows how to read the meniscus line.

On my test stand, the test port and the jet installed stand straight out or in other words at a right angle to the tube.

[RonC]

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Al Blatter had an article in the magazine Skinned Knuckles around the early 80's about flow testing jets. Does anyone know what issue that was? I would like to get a copy of that article.

[Sparky]

I don't know that, but my Rex Reheis carburetor book references an Al Blatter article from Secrets Magazine, that said you can convert 37.25" flow data to a 36" column by multiplying by 0.983.