Morris Minor Owners Club

Hi need to convert the cylinder head to unleaded, what parts do I need to buy? Thanks

I don't think conversion is a DIY job.

I think you need to get a motor engineering works to cut out the valve seats and replace them with specially hardened ones. While you're at it, get new valve guides and hardened valves fitted as well.

The easy way is to buy a reconditioned converted head from a reliable source, and simply swap heads. Some places do them on an exchange basis, using your old head as the basis for the next conversion.

(Sits back and waits for posts saying you probably don't need to do it at all, and / or of course you can do it yourself, all you need is some string, a small penknife and an engineering workshop in your kitchen .)

Don't bother!! Just run the car on ynleaded fuel - and check the exhaust valve clearances regularly. It's not a DIY job unless you have machine-shop facilities - and really - it's not necessary!

well I've noticed many of you have said there's no need of doing any mods but how many have had trouble free years from running on unleaded? I can't do the exchange basis as I'm in Malta and a cyclinder head is quite heavy to send to the UK!

Mine has had 6 years HARD running (summer months only) - and no problems. It's only a problem under continuous heavy load - ie thrashing the car flat out along a Motorway for long distances. A few minutes slog up a hill won't cause any problems. And worst that can happen anyway is that the valves recess slightly in to the head - if that happens - just reset the gaps - and then start thinking about either another head - or converting yours. An easier route may be to get a late Mini 998 head - already 'unleaded' from new. It has slightly smaller inlet valves (than a 1098 head - but same as 948 head) - so if this bothers you, fit the larger (but not by much) inlets which is a much easier task than fitting exhaust valve seats! If they are not done absolutely correctly - they can fall out and cause havoc inside your engine.

what's worrying me is that when the leaded fuel was going to be banned everyone was panicking about the minor as it couldnt take unleaded and now you're saying I can just give it unleaded? Thanks 4 patience and help

Exactly - 'panic' about nothing!! You can of course put some additive in the petrol - I don't bother because I believe it does nothing (except TETRABOOST which is genuine Tetra Ethy Lead) - but of course many do use the additive. Obviously it costs a bit - but if it gives you peace of mind .......

OK you gave me some peace of mind then! I won't use unleaded as I've seen only one type of additive and it's probably as bad as the petrol we get in Malta. I'll just give it unleaded and see how it goes! Thanks

My only other 'tip' on this will be to set the exhaust valve gaps to 15 thou to allow a little bit of valve expansion on a hot day. The later A series engines were gapped to this (and sometimes more) by Rover anyway.

OK maybe I'll try that but another question, sorry, can I fit e metro head straight on so to take unleaded?

If it's from a Metro 998 then yes. If from a Metro 1275 - then it can be fitted but some modifications are required. First - sink the exhaust valves into the head by 40 thou (1mm) - and then do a trial fit (using a 1275 head gasket) and see if the head clears the water pump - if not, file the top ledge of the water pump until there is good clearance. In both cases - the Metro head may not have a bypass hose. Either also fit the Metro non-bypass hose water pump, or just seal up the old bypass hose connection on the old Minor pump - or just block the bypass hose with a bolt! The 1275 head would give some power increase - but to get best advantage you would also need to fit the Metro carb and manifold - however your engine will run with the original carb etc if you don't need all the extra performance.