Morris Minor Owners Club

Hi there. I couldn't find an answer on this in the search. I have a standard minor and it HASN'T had the unleaded head put on because I was advised I wouldn't need it. However I am interested just once to try putting super unleaded in the car to see if I can feel a difference. Could it ruin the engine with it being a higher number or something or will it be fine?
I am aware it's not a sports car so won't change much, it's just out of interest.
Thanks alot
Steve

You will notice any effect you want to notice. An impartial observer, or any instrumentation you may care to fit, would notice none at all, unless you also adjusted the ignition timing, which would still have minimal effect.

Kevin

So it really won't have an effect noticeable enough? Would it harm the engine using super rather than standard unleaded? I have the original leaded head...

It won't harm the engine, only your wallet!

No, it won't do any harm. Higher octane fuel is less prone to pinking, which lets you run the timing slightly more advanced.

Hi,

The super unleaded will make a small difference - a very small difference to the performance without changing the timing.
The only thing that is noticable is that the engine won't run-on .

It may also have better detergent in it that the other fuels, so it may shift a bit of the dirt - but it really won't make much difference.

HTH

Colin

Thanks alot. I highly doubt I will even bother because of the cost v performance difference. I don't mind the car running on. Adds to the character. Thanks for the help guys

Unless you raise the Comp Ratio to ~ 11:1 - you don't need the super expensive petrol. Just stick with the very expensive stuff.

. Our local paper offers 3p of a litre at selected petrol stations nearby. As my sister delivers that paper I just chopped a load of the vouchers out of the spare papers. Not bad

High Octane fuel is more stable and as bmcecosse says, unless you’re raising the compression ratio, you won’t need it. You can use super unleaded in a low compression engine (But it won’t achieve anything apart from emptying you wallet faster) but you shouldn’t use ordinary fuel where the engine has a higher compression ratio.

As an aside, my MG Midget runs on super unleaded. As it stands, with the ignition timing set as it is, I get 106bhp. Shell Optimax is a bit more stable than other super unleaded petrol and is less prone to pre ignition (i.e. It doesn’t go bang before it’s supposed to as readily). If I used that, I could advance the ignition more and get another 4 bhp. Since I can’t guarantee to be able to get Optimax everywhere and since I don’t think I’ll notice another 4 bhp, I play safe; I don’t want to damage the engine!!