Petrol grade?

[Jordan]

I've been using 95 octane, non-ethanol fuel.
Would 91 also work OK? Sometimes it's available when 95 isn't.
2.25 litre engine in 1968 SWB, not sure if it's the original.

[Cannon]

We've been using 91 in DaOot & it gets along really well.

Might try 95 for a few tanks sometime to see if the Fuel usage changes

[incisor]

unless you have a hi compression engine 95 octane isnt going to buy you any performance increase imho

[JDNSW]

The 2.25 engine was designed to be fuel tolerant, and is quite happy on anything available in Australia today. A slight concern is the lack of lead, but valve seat recession is unlikely unless you do a lot of sustained high power (e.g. freeway) running. Presence of ethanol may cause deterioration of the pump diaphragm and some parts of particularly the Solex carbie, but I rate this risk as negligible with E10. I would be reluctant to use higher proportions of ethanol. For optimum performance with different fuels you should readjust the ignition timing, but in practice it is unlikely to make a significant difference.

John

[Jordan]

Good answers, thanks folks.

Regarding valve seat recession, as there's no easily available leaded choice I'll just motor on. I won't install hardened seat until the original ones wear out - if ever. It'd be a different story if I was planning a long trip, but that's not so.

Regarding performance, that's not something to expect from an increase in octane rating alone, but if compression were increased then a fuel change might be needed too.

[chazza]

Good answers, thanks folks.

Regarding valve seat recession, as there's no easily available leaded choice I'll just motor on. I won't install hardened seat until the original ones wear out - if ever. It'd be a different story if I was planning a long trip, but that's not so.



This engine was made with hardened seats as was the S1 petrol engine and the V8.

Years ago on a S1 email-forum when this topic was being debated, a Canadian owner who had owned a 2A from new, said that leaded-petrol had never been available where he lived and that he had done thousands of miles with no issues at all. A friend of mine with a 1970's Datsun is still driving around with the original valves and seats with no problems and his driving has included sustained high-rev running.

My engine re-conditioner when asked about the issue said that most valve seat problems they encounter, have been on petrol engines converted to LPG.

Incidentally; my Disco has done 180 000km on LPG since the conversion, with no problems with valves or seats :D

Cheers Charlie

[JDNSW]

This engine was made with hardened seats as was the S1 petrol engine and the V8.

Years ago on a S1 email-forum when this topic was being debated, a Canadian owner who had owned a 2A from new, said that leaded-petrol had never been available where he lived and that he had done thousands of miles with no issues at all. .......
Cheers Charlie

The 2/2a/3 four cylinder engine has cast iron valve seats not hardened seats (the S1, six, and V8 do have hardened seats), but the Canadian experience is valid - this engine was sold for a number of years in Canada when leaded petrol was not available, and no problems with valve seat recession were reported. The conclusion has to be that it is not a serious problem, although if you increase the compression ratio, improve the breathing, and achieve higher power, expect this to increase cylinder head local temperatures and hence the likelihood of valve seat recession. But even then, all you have to do is check the clearances at intervals, and if they keep closing up, be prepared to fit hardened seats before you run out of adjustment! (which will probably take decades)

John