I have no idea whether the head on my 1973 series 3 has been converted, I doubt it, however I am just sticking unleaded in until the valve guides wear out, and then I will replace it with a proper head.
I don't think it really matters on an old engine as it is likely to be worn out anyway, I have not had any problems so far.
Hi,
I am looking to buy a 1980 SIII with 2.25 petrol. I have a couple of questions I wonder if you can help me with.
1) Is it likely to be a 5 bearing crank engine - How do I tell ? 2) Would a vehicle from 1980 be ready for Un-Leaded, and is there any way of telling if it has been converted ?Many Thanks and Best Regards
Andy
Yes, my last engine blew it's head a while back, and the valve seats aren't worn in the slightest, depiste 2 years on unleaded.
Alex
May I comment that given you have been the proud and frustrated owner for such a short amount of time, you have collated an enviable knowledge and attitude one may 'normally' only expect from someone with years of swearing under their belt. Well done Larry! I knew you'd be a 'natural' to this :-)
Martyn
That is about when they changed - but I can't remember how to tell!
As sold, no, and there is no certain way of telling if it has been converted without removing the head. The 2.25 petrol engine will run perfectly well on unleaded, although the timing may need slight adjustment. As it has cast iron valve seats, it is likely to suffer from valve seat recession over a long period of running on unleaded, although whether this actually happens depnds largely on your driving style and how much life is left in the engine anyway - it may wear out before it becomes a problem. Remember this engine has been running (in small numbers admittedly) on unleaded in North America for over twenty years without a lot of problems being reported. Valve seat recession on this engine is likely to occur only with high exhaust valve temperatures such as encountered with sustained high speed, high power operation such as motorway travel at high speed or heavy towing. You can easily tell if it is becoming a problem by regularly checking the valve clearance and looking for decreasing clearance. JD
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