Help interpreting CIS Injector spray pattern

[Tidybuoy]

I did a quick injector test tonight on my '74 CIS. I pulled all of the injectors out and inserted into baby bottles and then lifted the airflow sensor plate to activate the injectors.

Two of the 6 bottles filled slightly less (see photo). I did not think any of the injectors were spraying a fine mist but they all sprayed a fairly straight stream of gas.

Should they be spraying a wide mist? All injectors sprayed a similar pattern.

Shouldn't the injectors fill the bottles the exact same per cylinder?

[thumbdoctor]

Theoretically the fuel system should deliver the same capacity of fuel to each cylinder. Some variables to consider:
1) Were the #1 and #2 injectors leaking before you placed them in the baby bottles?.
2) Is the system pressure and volume constant?.
3) Is the FD cutting the fuel off completely when the air vane comes to rest on the stop?.

I would start with a system pressure volume test (good pump, accumulator and filter ?) then get the nozzles cleaned. Once that is established further tests / adjustments can be performed.

[kodioneill]

They should have a conical spray pattern when plate is pushed wide open. If you lift the plate a small amount the pattern will be like you describe.

[john walker's workshop]

they should have a conical spray pattern and not drip. an injector cleaning might bring them around. now, swap 1 & 2 injectors with 3 & 4 and see if the issue follows the injectors or if the problem is the fuel distributor.

[manbridge 74]

I like to check flow at just off the stop, halfway, and all the way. Did have to replace one and now all mine flow to the same line.

[Tidybuoy]

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The spray pattern was similar to the top left photo but narrower. I'm pretty sure it was that way even at full pressure. They never sprayed like the bottom left photo (at any pressure). There was no dripping when I stopped the flow.

I will swap the injectors around and see if the problem follows the injectors or is a fuel distributor issue.

I was suspecting the fuel injectors because the car is idling a bit rough but runs at full throttle very well.

[boyt911sc]

Vern,

These are the criteria I used for evaluating CIS fuel injectors:
a). Injection flow pattern.
b). Operating or opening pressure.
c). Drip or leak test.

The injection flow pattern should look like a V-shape pattern, uniform all around, and atomized.

The recommended value for the operating pressure is between 36 - 52 psi. So having a set of fuel injectors with opening pressures close to each others is highly desirable. I segregate them as: Group #1 (36 - 41 psi.), Group #2 (41 - 47 psi.), and Group #3 (48 - 53 psi). All injectors with 55 psi. operating pressure are rejected and go to the dumpster.

Fuel injectors should not leak or drip during stand-by. Leaking fuel injectors should be discarded and not use at all. It takes only a few seconds to test a CIS injector and more than happy to do the test for FREE for fellow members. Actually, I like to ask for a voluntary contribution of $5 per set of injectors to cover the Techron fuel injector cleaner and gasoline during the tests.

In your case, I would install injectors #1 & #2 in another position and test them again. And see any changes in the results.

Tony

[Tidybuoy]

Thanks all!

After watching a few YouTube videos, I'm pretty certain that my injectors were not atomizing correctly. It was much more similar to a hose-end sprayer on a garden hose at full strength.

Tonight, I will switch the injectors around and see if the low volume stays with the injectors (I hope so) to rule out fuel distributor issues.

Because they were not too too expensive, I ordered new injectors this morning. This will give me peace of mind and at almost 40 years, maybe it's time for a new set.