C20 for towing

[SirRobyn0]

I have had very good luck with TH400s which is why I mentioned that combination. Yes, I will admit that combo is not really up to running 70mph+ all day. My "tow" vehicle is my 1993 K3500 with a 454/4L80E, 4.10 gearing. However, I rarely run over 65mph when towing. The truck will return ~13mpg on non ethanol at 55-57mph unloaded. Loaded or towing probably 10 mpg. I don't even check it anymore, it's not a commuter, I don't even put 700 miles on it most years. I have pulled the farm's big dump trailer with the K20, my primary concern there is brakes. Lord only knows what the K20 gets loaded/unloaded, whatever. It's bad, probably 8-10. The K20 is a 350/TH350 with 4.10 gears. It really does not matter, it's a chore truck and paid for. Not having a payment buys a lot of fuel even at $5/gallon. Older vehicles are more maintenance but I am not sure they are more than the stuff put out from 2019 to date. With the shortages there is a lot of material/parts substitution going on. I would be very concerned buying a newer truck knowing it sat for months waiting on parts.
Again all of this is my opinion. Add that to about $1.25 and you get a cup of marginal coffee at the Co-Op and a lot more opinions on everything from crop yields to drivetrains to tractor colors.....

This is good advice. Especially the part about the chore truck and it being paid for buys a lot of gas.

Everyone seems to be caught up on top speed and I think that's kind of ridiculous in a way. I'd be much more concerned about getting the truck and trailer up to speed and keeping there on hills. How about if we look at some numbers. So at 70MPH in drive or high gear in the case of the SM465 you'd be turning about 3,200 RPM. A little high for an all day run on the highway, but at 65MPH that's 2,900RPM. That's not a bad place to be at, your right in the power band of the engine and it can be held at that RPM all day. The old 70's Dodge based Motorhomes I had that's what I'd do. I'd run right around 65MPH as it kept me right about at 3,000RPM a great RPM to be at as you hit a hill. IF a guy had a 700R4 and had it built to withstand towing in overdrive, then you'd turn about 2,300RPM in overdrive at 70MPH. I fall back to my earlier statement that all combinations have there pluses and minuses.

 

[SirRobyn0]

Primary use is towing with not much day to day use and looking for an average available truck... 454, hands down. TH400 or SM465 are both fine choices. Try to stick with 3.73 or 4.10 gear. Use trailer brakes and a proper wheel/tire combo, then driving fast enough to keep up with traffic is no big deal. A healthy engine won't mind the RPM. A tired engine won't care for it, but a tired engine won't like towing 400 miles on a regular basis either.

If unloaded economy is a concern, both the TH400 and SM465 have options. Besides the previously mentioned Gear Vendors, you can install a Ranger gear splitter in front of the 465. Even if you don't feel like shifting two sticks to use all the gearing, it's still useful as an overdrive for high speed use.

I dream about that combination. SM465 and an advance adaptors ranger gear splitter. To bad they discontinued it a few years ago.

 

[bucket]

I dream about that combination. SM465 and an advance adaptors ranger gear splitter. To bad they discontinued it a few years ago.

Dang, I didn't realize they discontinued it. Now I'm really glad that I got one (slightly used) when I had the chance.

 

[Z28 Guy]

If anyone have a C20 for sale im looking for a truck... closer to Mississippi the better

 

[KnockingDiesel]

I use my C30 454 sm465 4.10 to tow all the time. I have towed 12k with my truck landscaping my yard with gravel (trailer and around 4 tons of gravel). The truck was slow to accelerate but kept up with traffic. I have a diesel 1 ton truck but it’s cheaper to run the 454. I tow cars all the time.

The only issue I have is 4.10 gears rev high on the free way so I limit it to 60 mph. For what you want to tow 454 with 3.21 or 3.73 would be good.

6k-7k loads are pretty effortless. The truck will tow 10k+ but you need to make sure you’re equipped to tow and stop a load that heavy.

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[Z28 Guy]

What a beauty you have there!! Im trying to learn fast about the old motors. My buddie with a 68 nova seems to know alot about the old motors. He told me to buy a running truck but slowly be building a 383 cubic inch build.

 

[Z28 Guy]

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Well shes mine. 87 model fuel injected 454 truck...

 

[Radiohead]

Wheels look sharp. Nice

 

[Z28 Guy]

Wheels look sharp. Nice

Thanks

 

[Ricko1966]

Personally I'd use a C with a mostly stock 350 and an 883 4spd. . Deep 1st O.D. 4th . If you blow it up anywhere you can have a rebuilt 350 the next day and driving that night.

 

[Grit dog]

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Well shes mine. 87 model fuel injected 454 truck...

Nice truck! The solid color with the classic GM white roof looks especially nice.
I was just going to respond to you that nowhere near Mississippi there are lots of C20s for sale up here. From beaters to trucks that look as nice as yours.
Not to mention a very nice C30 dually that hasn’t sold for a while.
Was that truck rockin the Detroit Steelies when you bought it or did you add them?

 

[Grit dog]

Looks like the 87 R20s with 7.4 were 4sp manual or 4sp OD auto.
What’s it got for transmission?

 

[SirRobyn0]

Personally I'd use a C with a mostly stock 350 and an 883 4spd. . Deep 1st O.D. 4th . If you blow it up anywhere you can have a rebuilt 350 the next day and driving that night.

I think that is one of my favorite things about these trucks. Not only are they easy to work on for the most part, but parts, at least the most important ones are still readily available. Yes, I carry my share of spare parts but that's mostly for convenience.

 

[Z28 Guy]

This truck have a turbo 400 with a fuel injected 454

 

[Hoss]

I see a lot of people on here saying not to do a Square for this project. I tow a 9,000 lb travel trailer with my 1985 C30 non dually, if you keep it running well it will serve you well. You can spend less than 10k on a good truck with no rust and less than another 5k on an upgraded trans cooler, trans rebuild, new tires, brakes, and a few upgrades for the 454. I could not and still cannot buy a modern 3/4 or 1 ton for towing for less than 25k leaving me another 10k to perfect my truck. Plus, every dollar I spend on upgrading my square will be reaped if I have to sell it. Not to mention the Mark IV 454 / TH400 combo is bombproof with the exception of the timing gear. I don't know for which years this applies but for my 1985 the camshaft timing gear was aluminum and nylon and when the gears get ground down enough you end up with interference and catastrophic failure. Do your self a favor and check the timing gears.