most if not all 1970's vintage datsuns with aluminum heads came with bronze intake valve seats and hardened steel exhaust valve seats. like dd said, we got unleaded fuel back in 1974 when the 75 model cars were new because the US EPA mandated it.
in all my years of working on Nissan products, I haven't seen any valve or valve seat failures that can be directly blamed on the use of unleaded fuel. as far as I know, all engine valve specs are the same regardless of which part of the world the engine will be used in. despite all the horror stories you may have or will hear, most of it it is a pile of crap.
keep the compression ratio under 10:1, don't use an alchol/ gasoline blend, make sure that there is not any water in it, and don't advance the timing too far, and you will be fine.
like was said before, we've had it here for almost 30 years, and don't have any problems with it.

Quote:

Darn
I always thought that the Tetra Ethyl Lead lubricated the valve SEAT, while the oil lubricated the valve GUIDE, since the valve stems are exposed to the lubricating oil in the rocker / cam chamber.

The A series engines are not necessarily compatible with LFG. In the US, it looks like they are, but i would not venture an opinion on 70's period Aussie heads.

You still have leaded fuel? Lucky swines, we lost lead in 95/96 and motoring has never been the same. Our unleaded (even 96 octane) is complete ####. Hot motors hate
it, my dad put a full house chrysler 340 out
of a racing boat in his car,(built in the good
ol days of lead) and its bareley driveable on pump gas with out swags of octane boost.
just prey that your unleaded is good quality.
:

In the USA we've been using unleaded fuel for 15 years. There are no problems with our Datsuns or other older cars. The unleaded fuel here has various compounds in it (e.g. MBTF) to give the same benefits that Dodgeman described for tetraethyl lead.

The pinging your mechanic mentioned is caused by low-octane fuel, not by leaded vs. unleaded. Undoubtedly when they switch over in ZA various grades of unleaded, including one with the same octane rating of the old leaded fuel.

If they do drop the octane rating, you will be able to get rid of the pinging by using:
- a lower-temperature thermostat
- reduce the engine timing slightly

datsuns have aluminium heads which means that the valve guides are hard enough..eg tehy will not wear out quickly due to the lack of lead.(the lead lubricated the valve guides) the only concern may be a drop in octane rating. In Australia, leaded and unleaded fuels (I may be wrong here) have the same octane rating and so here, unleaded fuel is just fine. Not sure about SA

Pinging will be the least of your problems if you use LFG [lead free gasoline] in an engine that is not made for it.
The Tetra Ethyl Lead in super petrol does two things

A. It reduces the volatility of the fuel. It makes the fuel burn, rather than explode under certain conditions. This then allows more comperssion & more advance in the timing, & THIS is where the extra power comes from.

B. It coats the exhaust valves & seats with a chemical version of lead, & this acts as a lubricant at the valve seat. It prevents these two parts from actually touching each other.

In older engines without the right valve & seat material, this lubricant is vital. When it is gone, the red hot valve welds itself to a few tiny spots of the valve seat at high loads [temperatures] & it pulls out a microscopic amount of metal from the seat. This gets blown out of the engine in the gas flow. Over many thousands of miles the exhaust valves eat their way into the seat & this is known as "Valve Seat Recession" It is not a pretty sight & your wallet will cry when it sees it

A decent engine reconditioner or head specialist will be able to quote you to fit suitable HARD valve seat inserts & should be able to tell you if the original exhaust valves are suitable. Once the cylinder head is rebuilt, just boogie on up to the "premium" pump & fill 'er up.
If you also fit a suitable Catalytic Converter as well, the environment will thank you too. ['scuse me while i go hug another tree]
Chris

Hi to all
I have received news sunday that we here in south africa will not get leaded fuel from 2006 onwards anymore.
Can anybody please give me advice on how to prepare my datsun for it?
I know that we will be able to get additives to add to the petrol that will give it the effect of leaded petrol.But I want to fix the problem not to do this adding all the time.
Will performance or pinging be affected when we do have to use unleaded fuel?
My volkswagen also runs on leaded at the moment.The mechanics said to me not to use unleaded fuel it will make it ping.What now if I must go over to unleaded in 2006?
Any suggestions? I know that it is not a Datsun, but here is alot of experts to ask anyway.

Those of you who read my Forum on "engine vibration when revved hard", I know now that it is the flywheel that caused the problem.

Thanks.