Rev Counter Sense Check

[Vista Estate]

Hi Gang,

I've just had to swap out my rev counter on my Mk1 Escort.

I'm running a 1600GT xflow, through a type 2 4speed 1600 sport gearbox into a 3.54 diff.

My rear tyres are 205/60 R13.

I remember seeing a post sometime ago with a cross reference of revs to mph. 

What should I be reading in revs at 50, 60 and 70.

Thanks

[Steve1967cortina]

I don’t have a chart, however there are many online calculators that will work this out for you, try this one http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

[Miniliteman]

The kph for every 1000 rpm is approx. 30 that is about 18,8 mph. So the rpm at 50 / 60 / 70 mph is 2660 / 3190 / 3720 .

[Rally Pack 2000]

I run 205/60 13s on my Mk2 with a 3.54 diff and at 3500 RPM its 110 Kph. That's our top speed limit here so with a 220kph speedo both needles point straight up along all our freeways. Very easy to keep steady at a glance.

[Miniliteman]

Is that 110 kph on the speedo or GPS?

[Rally Pack 2000]

8 minutes ago, Miniliteman said:

Is that 110 kph on the speedo or GPS?

On the speedo. What is GPS?🤔

[Miniliteman]

GPS is Global Positioning System; it's used by wifes and girlfriends to monitor where you are, how long you are in the pub / garage / shops. where you spend your (her) money etc.

[Vista Estate]

Thanks to all for your help gang.

I've done a check of my rev counter against multimeter and its over reading. This is probably a result of a viper coil as well as older electronics of the Ford AC rev counter. 

With the multimeter my tick over is 780 which is good and steady.

At 3000 on the rev counter the true reading is 2100

At 4000 it's 2900 and at 5000 it's 3600.

On the road test at 70 it was pulling 5000 on the rev counter which fits with your info as this is actually around the 3600 area.

Job done. 👍

No point in getting it calibrated at this point as I know the actuals.

[anglia58]

7 hours ago, Rally Pack 2000 said:

I run 205/60 13s on my Mk2 with a 3.54 diff and at 3500 RPM its 110 Kph. That's our top speed limit here so with a 220kph speedo both needles point straight up along all our freeways. Very easy to keep steady at a glance.

mine is 205/60/13 with a 5 speed, 3.22 diff, and dos 130kpm at 3000 rpm, our top speed is 100kpm, i drive that, i like to be a criminal, cheers marcel

[Miniliteman]

11 hours ago, anglia58 said:

and dos 130kpm at 3000 rpm, our top speed is 100kpm, i drive that, i like to be a criminal, cheers marcel

But Marcel, the speed limit is 50 kph in the city !

Police stopped Marcel, officer said "you were doing 130 kilometers per hour sir" . Marcel replied "that can't be correct I only left my house 30 minutes ago" 🤣

We call him "Mad Marcel" ....