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84 K20 "Ethel" Not an Sbc/NV4500/241C

Semi restoration of a 1984 K20 pickup. 5.3 LS, nv4500, np241c.
I triple checked, I'm actually tempted to put a mechanical gauge on this cause they're so dang cheap.
 
Might pull the trigger on some econo 285/75/16s what say the ck5 republic on this gearing scenario? 3.73 and a 285..
 
Roughly a 33" tire? A bit buzzy on the highway...I think you'd like a 35" or 36" better if you can fit them. 36" puts freeway R's at 2260 rpm at 65 mph. The 285's will have things spinning 2500 rpm at 65. Not the end of the world, but annoying to listen to.
 
Roughly a 33" tire? A bit buzzy on the highway...I think you'd like a 35" or 36" better if you can fit them. 36" puts freeway R's at 2260 rpm at 65 mph. The 285's will have things spinning 2500 rpm at 65. Not the end of the world, but annoying to listen to.

This. It's workable, but annoying to listen to. I have 31s with 3.73/700R4 in my Suburban. In 3rd gear I find the howling annoying In 4th gear it's much less so. Since you don't have O/D I'd stick with larger tires. Even 2260 is more annoying than 1800 or so. Haven't complained about the power availability with that combo, either, even in 4th. But, as Rene pointed out, I don't have a dump truck tranny, and I'm fairly easy to please anyway.


Here's some numerical data (just in case you haven't already graphed this).

sreidmix.PNG

With 35" tires it looks a little nicer.

sreidmix-35.PNG

That's more livable at highway speed. I'd still want a few more gears (and a lower cruising RPM range), but if you're keeping the 3.5-speed, I'd go with larger tires. Actually, I'd still be grousing about the engine howl at road speed, so I'd probably wind up doing some other ridiculous things to get the NVH down. ;)
 

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