C30, Dually, 454


Junior Member
I just bought a 86' C30 (454 automatik)last week and I'm really happy about
it. The truck is original but resprayed. Here in Germany we can drive as fast as we want to(on most Highways). My question now is, what is the highest traveling RPM for hours and what speed is it on the speedo(I have no tach). I want to drive through the country and dont want to loose time.
Thanks for helping me!

John DiMartino

PlowSite.com Veteran
With a 454,I dont think you want to sustain RPM's over 3750 for any extended time.I would keep them at 3500 max,for cruising.Buddy,you are going to burn some serious fuel at those RPM's,bring a gas card LOL.With the torque of a 454,if high speed driving is going to be normal,you might be better off geting a taller set of gears in the rear end.


Junior Member
central Oklahoma
Yes, get higher gears.

I don't know what the gear ratio is in your truck, but if it is a 4.10/1 gear ratio, you definitly need to either try to get taller gears or you need overdrive in your tranny. Without overdrive, I think mid 3's are best for high speed cruising in a one ton truck like yours.

I don't know if this is available for your transmition, but if you can locate and order one, a two-speed (overdrive and direct drive) gearbox that bolts in the place of the tail shaft on the tranny would be a great addition. This would give you a towing and a cruise range for your transmision and allow you to have twice the number of gears for performance sake. Here is a site that has a number of such items, check it out
http://www.drivetrain.com/overdrive.html I have one on order for my 4speed manual on a GMC "Sierra Grande 35."

[Edited by Kyle on 01-28-2001 at 11:56 AM]

mike reeh

Senior Member
i think you mean he would need shorter gears... something like a 3.07 would be nice or even 2.73 for high speed driving anyway.. keep in mind that these big trucks arent race cars :)



Junior Member

thanks for your help!
my millage was about 25 liters/100km (sorry, the metric system) at about 80 mph. i hope that isnt to fast(i still have no tach). that isnt bad for a bigblock i think. my second car, a mini cooper with 76cui needs 6 liters/100km, but it is not half the size. but i just need the truck to bring my showbike (harley, 120cui, 120hp@the wheel, 120lbs feet) around the country, the minicooper to have fun, and driving in the city. here in germany the gas is about 4.3$ a gallon (i think a gallon are 4.3 liters) and so its quite expensive to drive the truck.

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