74 k10 going 55 mph is at 3,500 rpm

[granthendrickson]

Cool, now we're getting somewhere lol. Go team! Now on to the 8mpg, Guessing you don't have a quadrajet on it.

Nope I’ve got a avs2 650 cfm edlebrock

 

[squaredeal91]

Does it run reasonably well, sluggish? How is the timing?

 

[granthendrickson]

Does it run reasonably well, sluggish? How is the timing?

She run’s pretty damn well, I rebuilt the engine around 300 miles ago. She’s got a stock bottom end, .30 bore, heads from a 71 camero, new edlebrock intake, 1103 summit cam, headers and a street fire msd distributor

 

[TotalyHucked]

According to this the axle is a 3.73 gear stock axle, how do I go about figuring out wether someone changed the gear ratio?

*nvrmnd, just saw the other replies lol

 

[MrHorsepowerLSx]

Any progress made over the weekend?

 

[JBswth]

I got a 1974 k10 with a 203 transfer case, turbo 350 and a 355 sbc. The rear gear is 3.73 and at around 55 mph cruising the rpm’s are up to 3,500. That seems a bit high to me, does anyone know what I should do to the truck to get lower rpm’s at 55? I’m also getting 8mpg.

3500 at 55 MPH? You must have 4:56 gears for the engine to be revving that high. Others are saying that maybe your trans isn't upshifting into 3rd, but I have a hard time believing that you wouldn't be aware of a problem like that.

J.B.

 

[JBswth]

I got a 1974 k10 with a 203 transfer case, turbo 350 and a 355 sbc. The rear gear is 3.73 and at around 55 mph cruising the rpm’s are up to 3,500. That seems a bit high to me, does anyone know what I should do to the truck to get lower rpm’s at 55? I’m also getting 8mpg.

A good way to tell is to jack the rear end and have a couple of buddies turn both rear wheels together one complete revolution, and you see how many revolutions the driveshaft turns. If you have 3:73 gears, your driveshaft will make a little less than four complete revolutions, but if it makes more than four, you don't have 3:73 gears, you have something deeper.

J. B.