Calculating RPM and general tach. questions

[JeffHK5]

I recently bought a 84 1ton dump with a N/A 6.2 that runs great with 78K original miles. I was wondering if a CK5 member with better math skills than I could help me calculate RPM. I know I have 1:1 final on the TH400 and a 4.10 gear and 29.5 tall tires but the formula escapes me. I'd like to put a chart on the dash of "RPM in relation to speed" to keep people from running it at red-line all day. I believe that 3800 RPM is the governed limit?

A tack would be nice but from the searches I've done it looks to be a spendy option.

Where would a elec. tach get it's signal , my dad owns a small trucking company and might have a parts truck I could lift one from.

Thanks, Jeff

 

[divorced]

This may help http://www.florida4x4.com/tech/gearcalc.php

 

[JeffHK5]

That's what I was looking for!

I put that in "favorites"

Thanks, Jeff

 

[imiceman44]

I recently bought a 84 1ton dump with a N/A 6.2 that runs great with 78K original miles. I was wondering if a CK5 member with better math skills than I could help me calculate RPM. I know I have 1:1 final on the TH400 and a 4.10 gear and 29.5 tall tires but the formula escapes me. I'd like to put a chart on the dash of "RPM in relation to speed" to keep people from running it at red-line all day. I believe that 3800 RPM is the governed limit?

A tack would be nice but from the searches I've done it looks to be a spendy option.

Where would a elec. tach get it's signal , my dad owns a small trucking company and might have a parts truck I could lift one from.

Thanks, Jeff

You got your calcs, now for the Tach:
Tiny tach is an inexpensive option and works great for $65 and it's easy to install in a few minutes, it takes a pulse from the injector lines.
There is also a pickup probe you mount on the alternator and you can use a regular tach.
I have both but got the latter with an engine I got so no idea where to get it or how much.

 

[JeffHK5]

Thanks guys, I've gained a little diesel knowledge in the last couple days.

My dads been a diesel mechanic/ owner operator for over 35 years and refuses to discuss oil burners on his own time!

Thanks again, Jeff