Flow Divider Balance

How balanced should the measured flow at the flow divider be on a 540?
Engine runs fine at all power settings but the plugs show an variation that matches a flow test at the divider. It idles and taxis fine even after landing on a hot day with no boost pump required, so I am not real keen to alter anything.

However the ports farthest (1&3) from the supply line at the spider are lean. 26 & 27.5 CC /20 seconds.

2&5 are normal flow is 29.5CC for 20 sec

6 has the heaviest flow and always has the most soot on the plugs. 33.5CC / 20 sec.

Any ideas from the FI specialists to balance the out put of the flow divider?

Thanks in advance.

Howdy:

Couple of points,

1. No one knows more about fuel injection than Don at Airflow Performace, a 30 second call will give you the precise answer

2. According to the Precision training manual they should all deliver the same fuel flow, perhaps a nozzle clean is in order unless you did the GAMI thing and tuned your nozzles ( AFP do it too).

3. Do your egts peak at the same fuel flow across the engine?

4. Refer to point 1

Flow Divider

This is a crude test at best. And basically if you see all levels within an eighth inch of each other when using Coke cans that?s pretty good. You made a comment that the longest lines were the leanest. Did you make sure that the lines were filled and all the air was out of the system when you started the test? 20 seconds of test time is not much to get viable data. You would probably have to run the test for at least 3 minutes to get meaningful data. Does EGT confirm the conditions as you increase the throttle off idle? This checks for intake leaks. So not to say that there is no problem but if you really want to know if the part needs attention the part should be flow tested with test equipment to accurately test the flow distribution at different total flows. We do this with a test stand that has a flow meter on each port. To flow test the part cost $40.00. To overhaul and adjust the flow distribution to get it in spec is $70.00.

Don

50 CC graduated cylinders at the spider before the injector lines. I was just looking for a reason why 1&3 plugs are always white and 6 always has dark soot. Idles smooth, runs smooth and the EGT s are within 130 deg at cruise.
On the ground I lean it half way to cut off, for peak RPM. No miss or stumble.

Boost pump flow volumes at the spider are consistent with the plug colors but perhaps it's irrelevant. There has been no change since I have owned it. Shipping parts across borders is not fun.

Thanks Again

If you are happy with how your engine is running then I would recommend doing a lean to peak test http://www.gami.com/gamijectors/leantest.php

This will show you which cylinders are getting more or less fuel in actual flight conditions, that is what you are really interested in. It will be interesting to see if the results of this test echo your ground test findings. With the information that you get from the lean to peak test Don may be able to make nozzle insert recommendations if things are out of whack.