Surging NAS Defender 110 1993

[polardoc]

My Defender surges quite badly when pushed hard (uphill) or with aircon on. Always starts at 2800 to 2900 revs in all gears.Can sometimes drive through it and it settles at higher revs but sometimes have to throttle back. Has been going on for 10 years (no shop can solve it!) and is not getting worse.
Any ideas, things to rule out -- fuel supply, electrical, timing,ignition module?

As an aside what is safe revs for this engine?

Thanks for any advice.

[mearstrae]

Which engine? Diesel or gasoline? Could be as simple as a vacuum leak.

'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S (Gone...)

[polardoc]

V8 3.9l gasoline. How to diagnose a vacuum leak.Could it be faulty vacuum advance.


PS
I had a Rover 3500 too, lovely car.

[mearstrae]

A vacuum gauge would be needed, it would also be helpful when setting the timing (and they don't cost very much). Yes, it could be the vacuum capsule (British term for advance mechanism) in the distributor, tested with a vacuum pump (or by observation, it should move when under vacuum). There's also something called the "RAVE" manual available for free on line that is real helpful in tracing problems or fixing things. It's a digital repair manual.

It's a shame the Rover P6 series wasn't appreciated, it's much better than the same year (or any 60's or 70's) Benz.