Ideas to make truck tow better

[George2615]

I agree with MossRoad about the low 1st gear. From your last post #10 it seems like you have the early trans with unsyncronized reverse. You should not have any problem starting out in low. Have you done a compression check yet. May just need to have the heads shaved and valves redone to get the power back.

 

[downslope]

That truck has an external hydraulic clutch slave cylinder, is that correct? If so, maybe there is an issue with that or the fork where it doesn't allow you to feather the clutch slightly but just dumps right in or out. The later trucks i believe had an internal slave cylinder that was combined with the throwout bearing.

 

[tcartwri]

The tires are 235 85 16s. That was what was on it when I got truck and I just had them replaced last fall.

I have no idea about what transmission or gear ratio I have. All I do know is in over drive gear, at 55mph, on flat road, rpms are at 1900 about.

That would work out to 4.10 in the diff. You could go to 4.88's but it doesn't address the problem of the engine bogging and stalling in first.

I would have to say the engine is worn out and has no compression left. It should easily move away at idle in first without lugging.

 

[Stimw]

Is the engine using oil? Possibly has burnt valves lowering power. ???
You might look for a 2 speed rearend and swap out for better gearing. Not sure if they made them for your size truck.
They were pretty generic made by Dana or Spicer or both and should swap out easily.
The 2 speeds just needed a switch to change gears because they used an electric 12V motor.

 

[tcartwri]

The other thing is that it may lean off idle due to your exhaust leak. That would definitely make it feeble off idle.

 

[namesray]

The other thing is that it may lean off idle due to your exhaust leak. That would definitely make it feeble off idle.

I was wondering this, but wasn't sure. Lots of people told me that fixing that manifold leak would add 25 to 50 hp for towing, but I asked for helping getting a load rolling or just for going up a hill faster? I don't need to go faster up any hill, truck is satisfactory for that, I just need help getting moving. No one knew if fixing the exhaust leak would make a difference about stalling trying getting moving with a load.

The cost to have both manifolds replaced was around $600. Do you think it would be worth a shot?

 

[farm boy00]

I was wondering this, but wasn't sure. Lots of people told me that fixing that manifold leak would add 25 to 50 hp for towing, but I asked for helping getting a load rolling or just for going up a hill faster? I don't need to go faster up any hill, truck is satisfactory for that, I just need help getting moving. No one knew if fixing the exhaust leak would make a difference about stalling trying getting moving with a load.

The cost to have both manifolds replaced was around $600. Do you think it would be worth a shot?

I would weld then to test this first before doing that

 

[some zilch]

i work on a fleet of 350s in larger delivery-type vans. all of them have exhaust leaks (isnt that a chevy thing in general?) and that does not seem to effect their power. these vans gross 17-19k every day, all day, and are driven by guys who beat them to death. you have an issue other then an exhaust leak

 

[zzvyb6]

First I would check the condition of your brakes to determine if any residual clamping force is on them. Starting off usually means you stopped. And if the rears are locked up, then breaking them loose takes some launch force. Easy to check. STop hard and see if you can push the truck by hand. Or, jack up the axles and spin the tires by hand.

Another way to get better launch would be to put on a tire size that has a smaller loaded radius. Your (LT)235/85R16 have an SLR of about 14.9" at 80 psi let's say for the sake of discussion. An LT245/70R17 has about a 13.7" SLR. There is a slight load capacity reduction, but the change in tire radius is equivalent of a 4.10 gear increased to a 4.38. Presuming you are running duals, that would require 4 different wheels & tires, but around here, junk yards are full of them. The LT245s have the largest reduction in radius that I could find for your load capacity. You could 'try it out' by dropping your tire pressures enough to get the same SLR change. All you would need is one try to see if it helps you enough. I'm sure you wouldn't go traveling at the lower pressure so I won't remind you to air them back up.

 

[dieselcrawler]

I will admit I haven't read this thread in detail today, but have been following it since it started... don't recall if the existing axle gear ratio is known or not, but I have extensive backround in '73-'87 chevys. A 2wd dually often came with 4.56 gears, and for good reason. Even with the granny low in the stock (T-10, I believe) truck 4 speed manual trans, you needed low gears when towing and hauling. No top speed, but without the ability to drop into low range like a 4X4 would have, they made up for it with low axle gears.

OP, check yer gears... if you have 4.10's or (ouch) 3.73's, you might just be geared too tall. If you have the GM 14 bolt axle, it's an easy swap if you find a complete donor axle, can be done in an hour with basic hand tools. And you don't even have to jack up the truck to do it.

Where are you in PA? Be willing to help if you're close enough and want to stop by...