Series IIIs R6 - Top Speed

Land Rover Series vehicles - The golden oldies

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Joined: 15 Feb 2015 09:30

Series IIIs R6 - Top Speed

Postby mikedup12 » 15 Feb 2015 10:19

I recently have been restoring a Seties IIIs R6, it has the 4.1 Chevy conversion in it.

I just have a concern the last few days regarding the top speed, at the moment I get 70km/h on the GPS at 4000rpm which is a bit slow for such night revs in 4th gear. I know the Landy is no speedster but I would like between 80-100 at 2500rpm in 4th gear.

From what I can see in documents and websites
Engine: 4000rpm
4th Gear 1:1 - 4000rpm
Transfer Case: Highest Reduction 1.53:1 - 2614rpm (cannot confirm reduction)
Diff Ratio: 4.7:1 - 556rpm on the wheels
Tyre Size: 245/75/R15, Diameter 740mm +/-
Speed = (556x3.1415x0.74)/60=21.54m/s x 3.6 = 77.54km/h

Ok it's not far off

The original tyre size 805mm

Speed = (556x3.1415x0.805)/60=23.43m/s x 3.6 = 84.36km/h

What are the options? Or is this the speeds I can expect to travel? Or is something wrong.

From what I have read the R6 should do 130km/h

Posts: 63
Joined: 04 Apr 2013 20:55
Location: Pretoria

Re: Series IIIs R6 - Top Speed

Postby JPC » 01 Mar 2015 20:42

Hello Mike

IIRC the transfer-box ratio on the standard series is 1:1.48, and the Santana box in the Series IIIS should be the same.

4000rpm should get you close to 100kph with 7.50x16 tyres.

You might have a low ratio gearbox/transfer-box in the vehicle with the speed you get at 4000rpm. If you can post a pic of the back of the gearbox or find the gearbox number then one can determine which you have.


Posts: 4
Joined: 15 Feb 2015 09:30

Re: Series IIIs R6 - Top Speed

Postby mikedup12 » 23 Mar 2015 22:07


I found the a couple of problems, namely the rev counter being set to a 4 cylinder :x and not a 6. The incorrect timing setting and dwell angle made the engine struggle at high rpm which is fine now I now get 75km/hr at 3000 rpm speed from GPS speed then shows 85km/hr. I'm wanting to change to HEI from points do you have any advise? I just did a 1000km trip with the Landy the weekend went well!


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