Need some VR help

My charging system was not charging reliably. Some days it was fine, some days no charge at all. Today I dug into it. I tested the generator multiples ways that I read online and it checks out great.

So I turned to the regulator. I checked the voltage output at the regulator and it was low., about 6.8 volts at a fast idle. I adjusted it up to 7.5 volts and everything seemed fine. I drove the truck and noticed that after a few miles my fuel, temp and oil gauge all moved the max of their travel....... Gas gauge read full with a half tank of gas, temp went full hot, oil pressure went to far right. After a couple more miles the system stopped charging (ammeter fell to dead center rather than slightly positive) and then my other gauges started working again. What the?????

Everything I read says that the system should be charging at 7-7.7 volts at fast idle. But it acted like too much juice was being fed to the gauges or ??

I think I'm in over my head here... And ideas or? I was originally planning to just get a new regulator but after reading up on it this morning it seemed that these don't fail but just need to be adjusted.

There are 3 adjustments and they are inter related, adjusting one can effect others and it is beyond the scope of what can be easly explained in writing. 6.8 to 7.2 volts should be enough to charge a lead acid battery.
why did you mess with it? If the battery is charged, it WILL read 0 on the ammeter. If it is not showing a discharge at speed (it can show a dis-charge at idle, depending on load) then all likely well.

I noticed that most times I was driving it the ammeter was on the positive side and would move with engine rpm. but other times the ammeter would sit dead center, and go negative when any load was introduced like lights, heater, etc. no movement with rpm, never any positive indication. I understood that to mean that it was not charging.

Tweaked it some more today. If I set the voltage output at 7.5v, and the current output at 7.8-7.9, I get the weird gauge reaction again of my fuel, temp and oil gauges reading very high. If I lower the voltage output to 6.8-6.9V and the current to 7.1-7.2 then my gauges read correctly, but if I turn the lights on then my ammeter shows a discharge. If I bring the rpms up the discharge minimizes, but going down the road it never reaches an even or positive reading on the gauge.

also, at those settings I only get a reading of 6.7V at the battery at a high idle.

I checked all the gauge wiring connections and everything is clean and tight.

I don't get it - these are supposed to be set to charge at 7.5-7.7V and have a current output of just under 8V..... but obviously something is affecting the gauges when set at those levels.

Keep digging.....

Jeff, I may be off base but..... a 6volt battery should charge at about 6.8 Not up any higher. These old vehicles as was said will show a discharge when the lights are turned on, That is why they dim, the generator is charging through the regulator at 6.8, which will "recharge" your battery(keep it from going dead) With the lights(and they draw a lot of juice)on that power comes from the battery. Again, generator and regulator, sound to be working correctly. If you want brighter lights, you can buy the halogen kind that work with 6volt. If you turn any electrical device on that has a motor or high draw, your ammeter will probably show a slight discharge, but your battery will still be charging. If you have the voltage turned up to higher than 6.8, you will probably "boil" your battery and shorten its life. And no, please do not use an 8 volt tractor battery in your truck. If your connections are good and the right size every thing will work correctly. There should be some posts/threads on here that give you ways to better supply your power needs for lights and such. As some say, use a ground wire and not the frame for your ground path in all your circuits.
These are my thoughts and observations.

If I lower the voltage output to 6.8-6.9V and the current to 7.1-7.2 then my gauges read correctly, but if I turn the lights on then my ammeter shows a discharge.
Keep digging.....

Ok, now you lost me, How and why did you set the "current to 7.1-7.2"? Current is read in amps and the regulator setting should match the generator that you have (30,42,45,50) Most have 30 amp generators.
Current setting must be done with a partially dis charged battery or better with a carbon pile load on the battery. Voltage setting must be done with a fully charged battery and 6.8-7.2 volts is the spec.
I wouldn't trust the dash gauge to set the current regulator.
There is also the reverse current relay (cut-out, as some call it) and that is a 3rd adjustment.
How are you making the adjsutments and which "relays" are you adjusting?
I think you are in over your head. But make sure you have a good ground wire between the regulator case and the engine block.
a fully charged 6 volt lead acid battery reads 6.6 volts at rest (2.2 volts per cell).

The more I think about it, the more I think you may have a grounding issue. 1st run the battery ground to the starter or engine block NOT THE FRAME!!!!! again, in case you didn't get that DO NOT RUN THE BATTERY GROUND TO THE FRAME! May be I should repeat that!
next run a braided strap from the block to the frame, and from the block to the cab. These strap should be heavy, 6 gauge minimum.
Last run a 10 gauge ground from the voltage regulator CASE to the block.
That should eliminate any grounding issues effecting the gauges or the voltage regulator.

100% on that CB89.
Another free bonus of proper grounding of every system is reducing the electrolysis. Rust is the enemy and eliminating it is the challenge. Electrolysis from an electric current running thorough the frame and other body parts will speed up the rusting. That water on the road is a vicious and efficient electrolyte and when combined with some current flow in the vehicle frame, cab and box the rusting is accelerated many times. Your distant tail-lights will glow much brighter if each one has a ground wire that terminates at the main ground CB89 described. American Autowire make a very affordable kit, #500717. www.americanautowire/../grounding
Proper grounding will help to make a less than perfect freshening last and can help to control that patina look that others appreciate. Don't give the resident rust any help to grow.