NissanDiesel Forums

philip wrote:
Driving at 60mph in 5th gear, what is the RPM?

And at 38 mph in 3rd gear, what is the RPM?

I'll have to get back to you on the 60mph rpm, because I cannot drive that fast to work. At 38mph in 3rd, my tach showed 2550-2600 rpm (it was hard to see in the dark). My tires are 220/70/R14.

philip wrote:And for the 1981-82 dash console?

Can you describe "dash console" in different words? I don't know what that is.

asavage wrote:

philip wrote:And for the 1981-82 dash console?

Can you describe "dash console" in different words? I don't know what that is.

Ok ... "Combination Meter"

See page EL-67 of your catalog.

1982 Datsun 720 Pickup
Factory Workshop Manual

http://asavage.dyndns.org/Nissan/displa ... age=20-067

Also, "Zoltan" says 38mph in 3rd gear registers 2500rpm. Not possible for accuracy.

It's 2600 rpm at 38mph in 3rd gear, I checked this morning again. I think with bigger tires like mine, it should register lower RPM at a given speed.

Zoltan wrote:It's 2600 rpm at 38mph in 3rd gear, -snip-.

http://users.erols.com/dmapes/GEARCLC.HTM

For 22.5 dia

Revised 9/27/07

For 23.5 dia

Zoltan's larger dia. tires puts his 2600 RPM right in the range of what I'd expect, given the numbers on that chart. Of course, I'm assuming that chart is correct, maybe not the best assumption, taking into account the two spelling errors, three layout errors, one unfortunate word choice (and worst of all: trim the fractional portion of the result!).

asavage wrote: Of course, I'm assuming that chart is correct, maybe not the best assumption, taking into account the two spelling errors, three layout errors, one unfortunate word choice (and worst of all: trim the fractional portion of the result!).

Haha HA ... Hehehehhee. The propeller speedometer drive / gear choice vs. engine RPM is all I cared about. The tire diameter to vehicle speed is a 'nuther matter. LOL

Should a GPS verify the speedometer speed to vehicle speed?

2350 rpm at 60mph in 5th gear. What's the stock tire size ?

Z,

I think that the stock size is 185R14. Without the sidewall ratio that is typically seen (ie 185-75R14) it indicates a fairly tall aspect ratio of either 85 or 90%. So, the stockers are narrow and somewhat tall for their size.

P185x75 isn't as tall as a 185x75 used to be.

In my case ... (you can tell I've been over this before. )






These tires should be 902 turns per mile ... X 3.88 rear gear ... X 0.81 5th gear (OD). Est 2834 rpm. Of course this static measure is not allowing for radius stretch at freeway speed. I'd agree with Al's 2600rpm at 60mph true road speed.

(Of course you speedometer WILL vary. )

Try this for getting info on tires, circumferences, radius etc etc.

Available in MM or Inches.

Easier on the brain

http://www.1010tires.com/TireSizeCalculator.asp

asavage wrote:Is $65 cheap enough for a diesel tach? Looks pretty darned easy to install, too.

The Tiny tach is/has been upgraded, old style has been discontinued, NOA. The new one is going to be $95. The new one is on back order, right now and at the moment you can order the new one online at the old price of $65. I just ordered mine this morning. They got rid of the battery finally, and the new one has a BACKLIGHT in the display now.

ecomike wrote: They got rid of the battery finally, and the new one has a BACKLIGHT in the display now.

NICE!! So you'll be able to see it in the dark. The battery IS stupid... when it dies so does the tacho. If I new that my truck will last 3 years, I'd get a new tiny tach.

Go to a truck parts supplier get a motorola 0-4000 tach. it hooks up to the alt. works great also lets you know when the belt breaks. I've had mine since the truck was new. 1981
JIm