DIY pop testing

I've been playing around with an old pop tester a friend has given me, just with some surplus injectors I had laying about. The tester is probably 20 odd years old. it has a crank handle which screws in to create pressure apposed to the pump handle lever type job, so is quite ghetto.

Seeing as I'm the type of idiot that likes to do as much as he can rather than pay the educated professional. I thought I'd have a crack at balancing a set of injectors, and if all seems well try them in the motor.

I have already converted to single stage by modifying the top hat. I have varied pressures from 330bar all the way to 370bar. I plan to run 330bar so will lower the higher pressured injectors down either by sieving through other injectors for smaller shims or maybe scrub the current shims down a little.

I do have an issue or two I need help with.
One injector pops once then streams. The nozzle is dirt clean but no matter what I do it streams. This particular nozzle I've noticed the needle jams each time I remove it. Is there something I can do to remedy this?

Something else I've noticed is that I have varied pressure drops after the pop. So injector pops at 330bar, pressure drops to 300bar. Where as another may pop at 330bar but the pressure will drop to 280bar. Could this ROUGHLY indicate flow? So a larger drop means more flow?

One injector pops once then streams. The nozzle is dirt clean but no matter what I do it streams. This particular nozzle I've noticed the needle jams each time I remove it. Is there something I can do to remedy this?

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Looks like you need a new nozzle. There is virtually nothing you can do to re-lap a worn needle to the worn nozzle. It could also be that the orifices in the nozzle have been compromised due to wear.

Something else I've noticed is that I have varied pressure drops after the pop. So injector pops at 330bar, pressure drops to 300bar. Where as another may pop at 330bar but the pressure will drop to 280bar. Could this ROUGHLY indicate flow? So a larger drop means more flow?

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A larger pressure drop indicates more fuel has flowed through the nozzle. You can verify this by collecting the fuel injected via 50 or 100 strokes and carefully measuring it. Since you can't really do a lot to change the flow through nozzles, you would be stuck if the flow is different. Flow matching with new nozzles is generally done by matching them in sets after testing a large number. This is not hard when you are selling them because you a) have a large number from which to choose and b) the variance between new nozzles from a quality manufacturer is very small.

Your last resort is to find someone who can flow match nozzles and ask them what they can do for you.

Good luck and cheers,

PH

thanks for your response. An injection shop local to me charges £135 to set up each injector. Which is nice to know if things go bad however I'd like to have play first.

I plan to use smooth running compensator as a guide to help balance the nozzles. Assuming all else is ok, compression. clean inlet etc. I think it may work. certainly worth a shot anyway

135 per injector? Buying a new set would be cheaper!

Sorry. £35 + VAT each injector