Thread: 3.5 high or low comp?

The pollution engines were 8.13:1
The high compression engine was 9.35:1

Some of the early pre pollution engines were some where between the 2

The Rover Saloon had 10.25 or 10.5 : 1

Have a look at this it might help you http://www.roversd1.nl/sd1web/

CR is generally stamped next to the engine number, by the dip stick. I have a 9.35:1 engine out of a 3500 saloon in the ol RR ute.

Originally Posted by bee utey

I have a 9.35:1 engine out of a 3500 saloon in the ol RR ute.

I assume you mainly run it on gas but what is the min octane petrol you can run in it and at what timing.

Cheers

Garry

Originally Posted by garrycol

I assume you mainly run it on gas but what is the min octane petrol you can run in it and at what timing.

Cheers

Garry

I don't use it enough to put petrol in it but it runs well on gas at 10 degrees BTDC just like the old P76 9:1 engines did. To run petrol over 9:1 I would get a dual curve ignition* or a manual (eg choke cable) distributor adjuster set with limits at 5 and 10 degrees.

*https://docs.google.com/viewer?a=v&q...sEfvKG1bFUeSyQ

Ok thanks - seems a bit complicated - I will stay with lower compression then for my engine rebuild.

Cheers

Garry

Ok next question:
How much boost can you safely run on the low cr engine?
What's the biggest weak point in the engine? The rods?

The weak point is the block and the crank caps AFAIK. That's why the 4.0 onwards engines were side bolted caps.

The con-rods and crank itself shouldn't have a problem with turbo and mild boost to about 8PSI (half a bar).

But a supercharger would be a better idea.