Al, nice to see you came in from the Yurt to post again.
What controller are you using for the 4L80E? I ask because if you aren't dropping gears enough as others have pointed out, you won't have any power to the ground.
How does your M35 do on the same pass empty? How would your M715 have done if you still had it on that pass?
I have a 6.2 in my M715 with a NV4500. 2000 pound trailer with a 6,000 pound M1009 on the trailer has me able to hold 42-48 mph in over drive and not get over 205° engine coolant temp on flat ground. I drop it to 4th and I can attack hills and get over them in the 52-56 range without getting the engine hot. But, if I ever get below 1,500 rpm in any gear on a hill. I will not be able to hold speed and usually end up around 20 in 3rd waiting for the hill to end. Or slower depending on the hill and head winds.
My point is your experience seems to track with mine when I don't keep the revs up or don't attack the flat at the bottom of a hill.
You have the ability to put any engine you want in there. It will probably be a show example of craftsmanship just like all your other projects. Try fuel filter, air filter, IP timing first though. Maybe even a Banks or 6.5GM turbo weekend project.
Hi Tim, Also really good to hear from you too. Lots has happened. Liz and I got sick of the drug houses around us in Oregon. The yurt was actually cool while I tore down the house to the ground. (black mold). But we moved the the northern Idaho panhandle after having had enough. 30K in permit costs, meth thefts, etc I have relatives nearby which helped us decide where to go. I am in washington by 1000 feet about 45 miles from Canada. Here the neighbors are really nice and I can do body work all day long and only disturb wildlife. I specifically required absolutely no neighbors near by. The ones we have are just super. I have become everybody's go too guy. They are all just normal people who just like space in Gods play ground. I have 500 miles of roads to explore around me. We are happier than ever here. I sold my Duece to a guy in Maryland. It was hard to watch it go. Loaded to the very top with engines, parts, tires including the M105, off it went on the back of a semi truck. I believe he is a member here. I can't drive it here as the roads are too tight. I collect firewood in the CUCV now.
My M715 was sold to a guy in North Seattle. I accidentally discovered it on Craigs list less than two hours from me getting absolutely butchered with Chev K30 axles and a diesel engine. I was going to go look at it but did not. I wanted to save it and all the work I had done, but could not afford it. You have to let things go sometimes. I struggled with that one.
The shift controller in my current and only remaining MV is a US shift. It works well and it does down shift. I should probably add that the CUCV came with a 6.5 injection pump in a box. I have a few parts for my truck here I need to install. A new harmonic balancer. etc Lots of good they do on the shelf eh? I have a car er jeep restoration that is due to go to it's owner in July. I have had stuff on hold for years because of that.
I think I will go after new injectors like Gimp suggests. Do a compression test and see what else could be up. I also want to say that having to preheat is kind of a pain here. We were -22-25 with a solid 4 feet of snow for over a month. That took planning to go anywhere. I have a coolant heater and an oil pan heater. It works but takes planning. I miss participating online. Now that our lives are finally settling after 7 years of trying to get a good house and shop under us, things are going just great. I appreciate all the input offered here. Everybody here at SS has always been great. Feels good to post again.