Thread: slow series 3, gearing or diffs??

The Series 3 diesel was always notoriously slow, and from memory only had a max speed when new of 55-60mph.
I don't think that the engine is powerful enough to satisfactorily pull higher ratios, perhaps that's why they were never fitted by the previous owner.

A full injector and pump service may help improve it's get-up-and-go.

Make sure that there is no brake drag, tyres are correctly inflated and no unnecessary stuff carried around all the time.

Good Luck with it.

Disco Denmark.

Havent driven a diesel are any of the others yourve got diesels to test against but the petrol s3,s are screaming at 100ks much more comfortable at 80. Looking at your sig you definatly have roveritus

you should be able to hit 85 on the flats without too much hassle (youd want a long runup tho) and about 95-105 as full tilt..

I regularly sit at 80~85 km/h, can do 90 on the flat, and have done about 103 going down a slight hill. It is much more comfortable doing 75. Mine is a suffix a diesel, from an early SIIa.
Do you have any black smoke when using full throttle while trying to accelerate? If so, you may have an air restriction. Your SIII engine will originally have a butterfly in the intake manifold. This is only there to provide vacuum for a boosted brake system. A SWB probably doesn't have vacuum brakes, so it is an option to remove the butterfly to get better air flow.
Are the injectors dribbling ar have a poor spray pattern? This can also cause black smoke. How good is the engine compression?
There are two screws limiting the travel of the bellcrank on the throttle shaft that goes into the fuel pump. One controls the idle speed, and the other the maximum running speed. Check that the throttle linkages are fully opening the throttle and engaging on this stop.
Ensure that the injection timing is correct. The workshop manual details how to set the timing. Check the camshaft timing. This is done using a dial indicator on the number one exhaust valve and the EP (exhaust peak) mark on the flywheel. Camshaft timing, and hence injector timing, can and does change as the timing chain stretches. This is why the camshaft chain wheel is provided with six keyways, so as to provide 1/6 of a tooth adjustment.
This is just a few things to check.

Aaron.