250i6 mods for Highway Driving

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Tdwmaxwell

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Jan 21, 2025
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Location
Athens GA
First Name
Tyler
Truck Year
1982
Truck Model
c10
Engine Size
250
At the moment I drive a 1982 C10 with the 250i6 and the SM465 transmission, don't know what rear end. I'm looking to make it a bit more comfortable as a highway cruiser. I've been doing more highway driving recently and it feels like I put a lot of strain on the engine (I don't currently have a tachometer so I have almost no idea what my RPMs are). I've been thinking about doing an engine swap to a V8 but was wondering if I should try changing the gearing first. Any recommendations about what I should try to make highways more comfortable?
 

Grit dog

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Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
If it’s an original 6cyl I’d be surprised if it has steep gears. But if that’s what you’re referring to, a V8 won’t help high rpm’s.
If your issue is just it doesn’t have enough power then more power is the solution.
 

ali_c20

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Location
Austria
First Name
Alexander
Truck Year
1974, 1979
Truck Model
C20, K5
Engine Size
350, 350
Welcome from Austria. Are you happy with the original engine and want too keep it? If yes I would install a tachometer (I prefer to have a tach in all of my cars) and check the rear end ratio. Tire size is also related to engine rpm.
You can use a Engine rpm calculator to get the rpm for current setup and the effects of the changes you want to make. No need for a tach then.

With that data I would see what needs to be done to achieve the desired goal.

This one has a list of popular transmission gear ratios:

https://www.crawlpedia.com/rpm_gear_calculator.htm
 

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