I have some good working yellow and black (pre -71) Bosch injectors which all came out of 1.7 stock engines.
I flow tested them at 43.5psi (3.0bar) and they all had a flow around 370cc/min.
Also tested them at 32psi (2.2bar) and they all had a flow of around 320cc/min.

This looks way too high to me since they all hav a rated flow rate 265cc/min at 43.5psi.

Anyone have any input on this?


/Lars S

No idea on the specs but I took a set of questionable injectors and sent them to Mr injector. for less than $100 I had a set of four rebuilt within a week to spec. https://www.mrinjector.us. Worth every penny and considering their value - easy to get your money back if you are selling them.

Ive been using him for years and at least 200 injectors. Great guy, great service.

Hi Lars,
Bosch produced 'early black' D-Jetronic-injectors in 3 different flow rates. You have to check the Bosch # to be sure they fit. Tell me the # - I can check it.

Your question concerning the flow rate: Bosch used a special testing fluid, no fuel for testing. More like naphta, a standardizised fluid. The flow rate of the D-Jet-injectors was tested at 2,0 Bar or 29 psi.
Other injectors - like that for the L-Jetronic- were tested at different pressure.
Some comparisation tables note all ijectors tested at 3,0 Bar to make them comparable. But there are some obvious mistakes in the tables I know, maybe they copy from the others...

Injector rebuilders normally don't measure the flow rates but compare the injectors to the others of the same type only.

Regards
Norbert

Thank yuo Norbert, that explains a lot!
Will check the numbers on the black ones later.


However I have now also tested the constant open injector flow at 28.5psi (2.0bar) , the result was 280-290cc/min which is pretty close to the nominal 268cc/min which is listed as the nominal flow.
My injectors are all old, could a worn injector valve seat or needle increase the flow. (besides that I dont have the special Bosch test liquid).

Thanks again!

/Lars S

Hi Lars,

wear will increase the flow a little bit... but this doesn't matter much.

Bosch allowed a tolerance of 5%, your injectors will all be very fine and show even 'better' values when you use the naphta fluid.
An engine running a little bit rich is better than a little bit lean...

But make sure they don't leak, stay totally dry at the top.
This is not repairable.
They could begin to leak after some time under fuel and pressure... I have so many leaking ones.

Send me your email-adress by PM and I send you an interesting document in German language. It will be readable for you.

Regards
Norbert

Most injectors fail if they leak @ the body or @ the pintle which is caused by wear but mostly by moisture in the fuel that erodes the taper on the pintle and seat.
Generally the injector will drip with a pressure test and under an energized state (open) the spray pattern will be uneven and provide poor atomization and a rich condition.
IMO the FI fuel filter needs to be changed more that many think if the car has been sitting or not used a lot or it has the dreaded tank rust .

Many thanks for the info!

Yes, I have a bunch of old leaky injectors myself, when I collect an old set of 4 Im glad if one or 2 does not leak.
I find the most leaks at the upper part of the injector body where the plastic meets the metal.


Thanks again!


/Lars S