Dad's Rover P5b Coupe

Is it an early one? IIRC, they dropped the compression ratio round about '72 making the requirement 98 octane. My old P6B with this engine was fine on 97 octane unleaded - although this might not be available in your country? Otherwise, just retard the ignition to stop pinking - it's very audible on this engine.

FWIW, it should not have been troublesome to start normally except when very hot - they suffered badly from fuel evaporation. Cold starting should be near instantaneous.

Hi Dave,

yep it is an early one, i think. It's a 1970, is that early? The compression ratio stamped on the block says 10.3:1

Wonder if they lowered the compression by changing the heads or the pistons? If it was done by changing the design of the head, i might be home free. Since those were exchanged for factory new ones when we rebuilt the engine. Perhaps i had better lift off a head and measure it..

Happy motoring Henrik Badger

Hi again Dave

The trouble with starting was when cold. When warm, it started right away. I've had to pick up Mama-san many a times, always to a song of "never will i drive that piece of junk again". But the lure of leather and automatic gear got her again and again :-)

I've just been told that we can in fact get 98 octane leaded fuel here. Even 100 octane is available as aviation fuel. Never knew....

Happy motoring Henrik Badger

Pistons.

I hope they fitted the later SD1 types which are much improved - and if they did it will run with more advance on low octane without pinking.

I'd have thought they'd have used current pistons at the re-build too, so IIRC 9.75 : 1.

Is it an auto choke type? They often give trouble, although can be fixed - most just don't understand them. It's actually a separate starting carburettor that adds to the mixture when it's cold, rather than the more common SU way of moving the jets. But anyway, there is a manual choke conversion available.

Aviation fuel is leaded, too. The early HC V-8 was a great deal more lively than the later one. The SD1 engine brought back most of the lost power on a lower compression, though.