Morris Minor Owners Club

Hello All

Silly question I know but better to ask now than have something go wrong!

Was just wondering, Im replacing a leaded A series with an unleaded one. Will I need to drain the tank of unleaded fuel which has an additive in with it?

Or can I still use the fuel in the tank already as long as its diluted enough
with unleaded fuel?

Cheers

i have had the same dilema i filled up the tank with unleaded ,engine still runs fine.i am not an expert though

Should be OK for one tank full - and when it gets to half topp it up so you have 50/50 mix.
Only thing is I'd be tempted to just drain the tank and refill with unleaded - chances are to set the new one up would be best done on the correct fuel.

You can happily use leaded fuel for an unleaded engine as long as it doesn't have a catalytic converter. The additive will do no harm to the engine itself so don't worry about it.

Perfectly safe as mentioned above. The only thing you might get, is if you set the timing and mixture using leaded, you might get slight pinking when you switch to unleaded if the RON values of the two fuels are different.

If this happens, just retard ignition a degree or two

Cheers All, that is most helpfull indeed. Ill see how I get on and let you know my findings.

All the best

Tom

Just run it - it will be fine!
How do you know the 'new' engine is for unleaded ?

Ah haa! Well you see this is my next question. Is there any definet way of knowing if it is an unleaded head?

Are there any identifying marks of anykind? When I bought it I had a reciept made out in case of such an issue,it was adverstised as unleaded and thats what I paid for!

Unfortunately without a proof of purchase from the supplier confirming that it had been converted to unleaded the only absolute way is to take the head of and check the exhaust valve seats and often they need close inspection as its not always obvious that inserts have been put in.

As Kevin says - it's all in the head - only the exhaust seats will have been made 'unleaded' and higher spec exhaust valves should have been fitted. Nothing else changes. Unless there is something wrong with your existing engine - leave it be ! Just swap the heads over if you really want to go 'unleaded' - and IF the new head has been converted.

I don't think that there is a problem using leaded fuel with an unleaded head. Perhaps you are getting confused with the problem of using leaded fuel with a catalytic converter which is a no no.