3.54 rpm at 60mph chart error?

is there an error in the 3.54 rpm chart added to the handbook…in the 60 mph horizontal row…, shouldn’t the true rpm (last column) have rpm LOWER than the calculated mechanical rpm in top, which it is in all other speeds. Top shows…2364 and true 2602…seems it should be 2302 or something close…a bit less than the top…certainly not 2602?
has this been discussed, corrected…I did not find it.
I suppose it can be calculated using the spreads from the other speed ranges…I will fiddle with it.

So this was a separate page added? I don’t have it.
Were there others? Mine would need a 3.64 ENV version.

page 14 of the XK120 “Handbook” has 3.77 and 3.31. A page was added, usually to the inner of front cover for the 3.54. I have not seen a similar add for other ratios…3.64 would be early…maybe there was an early handbook, also no page I know of for the 3.27.

so…3.54 shows…in top gear
mph rpm rpm adusted for tire radius at speed, bias 600-16.
50 2195 2179
60 2364 2602
70 3073 3017
80 3512 3424
90 3951 3822
100 4390 4211
110 4829 4585
120 5268 4951
130 5707 5302

tire circumference due to centrif expansion would show less rpm at speed and does, in the chart…except for at 60mph…a bit less than 1% at 50mph. not quite 2% at 70mph…so…lets say 1.4% at 60…a guess…would be 2330rpm, certainly not 2602.
math not my thing…hows it look,.,? Who has a 3.54, with 600-16 tires that are about 28 in diam…and wants to go 60mph, read the tach…and report back.

Who has a 3.54, with 600-16 tires that are about 28 in diam…and wants to go 60mph, read the tach…and report back

Not sure how accurate my tach and speedo would be.
I have the 3.64 so next time I’m out cruising I’ll take some readings.

the speed per 1000 revs in 4th is the key…nice to see the 3.27…you don’t see that much…I had the 3.27 on my prior 120 and like it a lot…compared to 3.54. I prefer long legs. My brothers 120 had the 3.77… I want the lower rpm at 65-70mph. I am interested in verification of the revs at 50mph, 60, 70mph …from anyone with a 3.54 and tires close to 28.2 in diameter (which will be about 27.6 loaded on the car. Nick

You are correct My 120 book has that same error on the added page for 3.54.

Hello Nick,

I have 3.54 and 6.00-16 Michelin Radial Pilot. My car is still in winter dreaming, will start mid/end May, so can´t provide a picture.

Here in Germany 100km/h (60 mph) are allowed on rural streets so is frequently used. From memory at 3000rpm I see roughly 63-65 mph on the tach.

Don´t know the diameter exactly from the Michelins, but you could find at Michelin Classic for sure.

Best regards

Thomas 674213