What RPM do you run?

[twithers]

I recently bought an 88 c15 which has a broken speedo. I have an aftermarket tach installed that has an adjustable marker arrow on it, so I have put the marker at the rpm the engine is running when I'm doing 65 on the highway, as a speed reference.

The only thing is that I have a Turbo 400 transmission installed, which is the 3 speed without overdrive. So I'm wondering what you guys run for RPM while going 65 in that same gear. So if you have the 700R4, it would be the RPM of your engine at 65 before your tranny drops into overdrive.

Thanks for the info.

 

[slowburb]

Try this:

http://tri-5.chevyrides.com/rpm.php

 

[twithers]

That is very cool.

It has 3.55 already entered for the rear end. Is that right for the stock rear diff on an 88 c1500?

If so, the calculator says I should be running 2667 rpm at 65, but my tach shows roughly 2400 rpm. Maybe that's just inaccuracy in my tach.

 

[twithers]

I checked my RPO code and if it's still accurate, the GU4 code is for 3.08 rear diff. That does make the calculator alot closer to what I'm actually seeing.

Thanks for the help.

 

[slowburb]

Of course, man. Glad to help.