Fuel injectors

I am helping out an fellow next door that has an IMT 560 deluxe tractor.It had sat for 5-6 years,without starting
.When I started this project I was unware of a few "issues" that came apparent as things unfolded.
First was the exhaust manifold was broke on both ends and leaking very badly.I bought a new one and replaced the old one and when we started the tractor there was still a wheezing that came from the top of the motor.We could not see where is was leaking from, so we pulled the fuel tank and found that the wheezing was from around the fuel injectors on two of the cylinders.We pulled the two injectors and saw where both injector bases were black on one side of the injector,or I should say the brass washer under the injectors.Both of these injector nozzles appeared to be plugged and not working which would account for the rough idle,and the popping at the exhaust.
We are having all 4 of the injectors serviced and adjusted.
My question is,will these injectors need to torqued down when we replace them?And what should they be torgued at?
The injectors are mounted on studs turned into the head.There are jam nuts on the studs that are bottomed out against the head.Do they belong there,or are they meant to be a jam nut against the injector.The reason I am asking is I am not someone who is used to working with the fuel injection system,and it looks as if someone else has been working on the motor,and that might be why it was parked 5-6 years ago.
Hoping a few of you guys can help me out.Thanks

From what i can tell by your description i would say the nuts on the studs under the injector flange should not be there if it prevents the injector from compressing the sealing washer down in the bore.
After proper torque of the injector (with new copper sealing washer) hold down nuts there should still be a little space between the bottom nuts and the injector flange.
If not then i would remove the bottom nuts as they really don't serve a purpose there unless they are part and parcel of the stud.

Sorry,.can't help you on the torque value

Thanks Bison, there is small amount of thread between the nut that bottomed out against the head and the injector flange. I was unsure of why. I will keep looking for the torque specification.I appreciate your help.

Patrick