dd 671 ti

The solid rack will not come back if an injector completely locks up, the spring load rack will bring the other injectors down.
A spring loaded rack will bring all else down but a lung will keep trying to make power.
I have never heard of a locked up injector not able to be pulled down by a hard rack. I guess it could happen.

That's why you have a shut down flapper on top of the air box. You do have a emg shut down flapper?
Stif injectors show themselves by loping at warm idle. The governor will only push so much and a half second late on a stiff rack. Buffer spring can only do so much. If you have a bad injector dragging, you would know something is up before total lock up (again, never seen a complete lock up).
My self; I would prefer the 2 screw rack (I was raised on 2 screws) and old racks.
During my tunes, I can bring a 2 screw bank in perfect just by leaning on the lock nuts. The timing tool just rides on the spring top ah so sweet. Many hours their still in place.
Takes a few extra minutes on the spring load rack as I'm constantly rocking and checking. There is room for slop and you aim for the best.
I can not tell you if any performance is lost or gained with either rack.

Bad runaways are usually caused by a bunch of other stupid and poor maintenance issues, Keep those shut down flappers in check. Spend that money in proper maintenance schedules and services.

Ya gotta get her off the dock before any loping idle concerns come to point. I am not a fan of dockside warm ups. Head temps and pressures will never come up tied to a dock.
One of us is in your hood. I'm in Jax. I'm sure a few of us are closer. Put on some coffee and lets go put a cruising hour or two on them.

I recently changed to the new model racks, and why not?
Why not prevent any risk for $500…I did, and FYI, PC Industries LLC in Wyoming has the on stock.

Furthermore, a non or not correct functioning injector is easy to detect, just get the valve cover off, put a towel on top of the cylinder head (to prevent oil spills), start the engine and push, with a large screw driver, on each injector. If the engine is not idling different, you injector is not OK.

Before even taking the valve cover off, I use an IR gun to see the temp of each cylinder's exhaust as the engine warms up. Easy way to see how each cylinder compares and where to look first.

I agree, but is not specific how to test an injector...

Look on youtube for a video of how to test a DD or Detroit Diesel injector. It's not hard at all.

I'd post a link but I'm not sure if it is allowed.

Go for it, If it does not link to a competing site I am sure Carl has no objection.

Who said he had a bad injector?

Now he said...LOL
(just wanted to share some useful info, in case off...)

Proper operating of the governor, could be limited by the bearings, I was told.

P46 may be referring to the tube end bearings that can be an issue also. Buffer spring and it's, rubber tip. I even found the cotter pin interfering with the linkage. Without rpms up and oil flying everywhere as it's spose to, all of the rack and contact points can get stiff. I'm sure there could be more that could cause a lope in the idle before anybody wants to blame injectors.
Run her some. Get em hot, blow out some slobber. Come back with a big smile and brag a bit.