Injector pump timing:
No gains to be made there, with either fuel mileage or power. Advancing increases the noise/rattle and increases bearing wear (confirmed by oil analysis), and retarding shoots the EGT too high.
Injector pump max fuel adj:
Didnt notice much, but there was slight improvement in power. Fuel efficiency dropped slightly, also.
Transmission:
I have concluded that the torque converter is the culprit to the higher engine RPM's and the problems shifting. Stock TV cable adjustment settings are best. I have found a torque converter for this transmission from BD, but the bolt pattern is listed as "Dodge" pattern. If anyone has any info (or reference material that shows) that this is the same bolt pattern as the Isuzu 6bg1t, I would appreciate it.
And last, but not least, a very strange issue that I thought sharing would help someone else diagnose without spending several hours figuring out.
(terms listed for search engine tags) Isuzu NRR 6bg1t or 6bg1 engine fails to shut down with key turned off:
In a nutshell: when you turn the key OFF, it disconnects the 12v system from the battery, yet the fuel shutoff valve requires power to run the little electric motor to cycle the valve OFF. The power used to run this motor comes from the alternator output circuit (which is disconnected from the battery when the key is OFF). So....if your alternator is bad, the engine will not shut down. Oh, the hours I spent disassembling the dash to test all the little components in the fuel shutoff circuit....
On the bright side, this alternator is very stout. It has over 250k miles on it and the bearings and (steel-looking) armature are in excellent condition. It also uses VERY long brushes, so they last a very long time. The brushes (installed by SAS) cost less than $50.
