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Leaded and unleaded (may sound stupid)
speedyxjs - 15/7/08 at 07:25 PM

This has confused me. I ordered a reprinted manual for my new old mg midget and it says it should be filled up with 97 RON 4 star.
Can i run it on 97 RON unleaded?

[Edited on 15-7-08 by speedyxjs]

Mr Whippy - 15/7/08 at 07:28 PM

yes it’s the same, it will be fine.

neilj37 - 15/7/08 at 07:32 PM

97 RON is super unleaded rather than the regular unleaded which is 91 RON

[Edited on 15/7/08 by neilj37]

Howlor - 15/7/08 at 07:34 PM

The only difference I presume is that you will burn through the valve seats without the lead additive.

Steve

mr henderson - 15/7/08 at 07:35 PM

quote:
Originally posted by speedyxjs
This has confused me. I ordered a reprinted manual for my new old mg midget and it says it should be filled up with 97 RON 4 star.
Can i run it on 97 RON unleaded?

Only if you don't mind the valve seats getting all f*cked up. You need to get harder valve seats fitted

John

Damn it, must type faster

[Edited on 15/7/08 by mr henderson]

speedyxjs - 15/7/08 at 07:37 PM

quote:
Originally posted by Howlor
The only difference I presume is that you will burn through the valve seats without the lead additive.

Steve


thats what i thought. I meant to add without adding additive

blakep82 - 15/7/08 at 07:43 PM

i heard years ago that old engines that were running leaded petrol for years and years were ok to run unleaded for a while as they built up enough lead deposit in the fuel system to be safe, but how long for (and if its true) i don't know.

Howlor - 15/7/08 at 07:56 PM

There are those things you drop in the tank that are supposed to do the same job as the lead.

Steve

trogdor - 15/7/08 at 07:57 PM

if you keep the revs down and don't do many miles you will prob get away with it.

But i think this is going to be your daily driver?

You can buy lead additives that will help but you prob be better getting the heads modified.

GeorgeM - 15/7/08 at 07:58 PM

I run my frogeye on unleaded with an additive.

Other solution is a metro head

GeorgeM

rusty nuts - 15/7/08 at 08:13 PM

Other solution is a metro head

GeorgeM




1500 ?? IIRC So Metro head is no good?

DRC INDY 7 - 15/7/08 at 08:21 PM

castrol valvemaster + and it does work ive used it for years in many a classic car

plus i will be useing it in my indy

mr henderson - 15/7/08 at 08:22 PM

quote:
Originally posted by rusty nuts
Other solution is a metro head

GeorgeM



1500 ?? IIRC So Metro head is no good?


1275 Metro

iank - 15/7/08 at 08:30 PM

Midget had two engines during its life

1961-1974 Chrome bumpers had A-series in 948, 1098 or 1275cc

1974-1980 Rubber bumpers had a 1500 Triumph spitfire engine (complete with chocolate crank).

rusty nuts - 15/7/08 at 09:09 PM

quote:
Originally posted by mr henderson
quote:
Originally posted by rusty nuts
Other solution is a metro head

GeorgeM



1500 ?? IIRC So Metro head is no good?


1275 Metro



Rubber bumper Midgets were NEVER fitted with the A series engine so a 1275 Metro head will not fit. Uses the same engine as the Triumph Spitfire

dhutch - 15/7/08 at 09:13 PM

quote:
Originally posted by trogdor
You can buy lead additives that will help but you prob be better getting the heads modified.

Dont know anything about other engines, but in landrover circles the consensus seams to be to run it with a splash of addative, which will proberbly be fine. And if its not then the valve seated needed doing anyway!


Daniel

britishtrident - 15/7/08 at 09:17 PM

quote:
Originally posted by blakep82
i heard years ago that old engines that were running leaded petrol for years and years were ok to run unleaded for a while as they built up enough lead deposit in the fuel system to be safe, but how long for (and if its true) i don't know.



Yes in the short term -- but this engine is likely to have used up all its leaded memory effect years ago.

Also if it is a 1275 A engine they are notorious for burning exhaust valves in the centre pair of cylinders.

britishtrident - 15/7/08 at 09:23 PM

quote:
Originally posted by trogdor
if you keep the revs down and don't do many miles you will prob get away with it.

But i think this is going to be your daily driver?

You can buy lead additives that will help but you prob be better getting the heads modified.


Nothing to do with revs but a lot to do with the end gas temperature in the cylinder --- ie wide throttle opening. Also a weak mixture or retarded timing will overheat the valves.

britishtrident - 15/7/08 at 09:24 PM

quote:
Originally posted by Howlor
There are those things you drop in the tank that are supposed to do the same job as the lead.

Steve


No the only good they do is to the sellers bank balance.

britishtrident - 15/7/08 at 09:29 PM

quote:
Originally posted by rusty nuts
quote:
Originally posted by mr henderson
quote:
Originally posted by rusty nuts
Other solution is a metro head

GeorgeM



1500 ?? IIRC So Metro head is no good?


1275 Metro



Rubber bumper Midgets were NEVER fitted with the A series engine so a 1275 Metro head will not fit. Uses the same engine as the Triumph Spitfire


True Never factory fitted --- a lot have been fitted with ex-Marina engines over the years.

Fatgadget - 15/7/08 at 09:48 PM

Out of interest has anyone actually experienced burnt out valve seats first hand through running low ron fuel?

andyps - 15/7/08 at 10:42 PM

quote:
Originally posted by Fatgadget
Out of interest has anyone actually experienced burnt out valve seats first hand through running low ron fuel?


It isn't the RON which is the problem for valve seat recession, it is the lead. Shell Optimax or Tesco 99 will still get recesssion in a car designed for lead. The lower RON will just mean it may pink under load and won't develop as much power as it should.

The Castrol lead additive is very cheap in overall terms and worth using as LRP is becoming very hard to get hold of now. Don't know how much genuine 4 star is if you happen to find somewhere selling it.

If running unleaded when it should be leaded the important thing is to avoid steady throttle openings for prolonged periods - that is what burns the seats away so motorway runs are the worst.

Paul TigerB6 - 16/7/08 at 12:16 AM

quote:
Originally posted by DRC INDY 7
castrol valvemaster + and it does work ive used it for years in many a classic car

plus i will be useing it in my indy


It better had work - otherwise i spent 4 months wasting my time evaluating the production process for production over here for the UK market!!!

smart51 - 16/7/08 at 07:02 AM

quote:
Originally posted by neilj37
97 RON is super unleaded rather than the regular unleaded which is 91 RON


The lowest grade sold in the UK is 95 RON.

speedyxjs - 16/7/08 at 07:03 AM

Cheers guys
Iv got some castrol valvemaster and used that when i came back after picking it up so il just keep using that.

adithorp - 16/7/08 at 07:31 AM

With leaded petrol as well as acting as an octane booster the oxides of the lead coat the valve seat and that prevents wear. Without lead you need hardened valve seats to prevent this. Lead substitute will work according to the producers. If the seats are wearing then the tappet clearences get smaller and the valves don't seat properly, gas escapes and the valves burn out.

Use a substitute and check the tappets regularly and you should be OK.

An alternative to those ball things in the tank/fuel catalysts is before getting in the car, to stick 2 spoons up your nose, spin around shouting "Dooby,dooby I'm a loony" then jump in and away you go; problem sloved!

adrian

Marcus - 16/7/08 at 09:52 AM

Leaded petrol is still available, there's a garage near us which sells it. A lot of the classic MG guys go there. But.....it's over 8 quid a gallon!!

andyps - 16/7/08 at 04:06 PM

quote:
Originally posted by Marcus
Leaded petrol is still available, there's a garage near us which sells it. A lot of the classic MG guys go there. But.....it's over 8 quid a gallon!!


Isn't unleaded somewhere near that now anyway!

rusty nuts - 16/7/08 at 08:24 PM

quote:
Originally posted by andyps
quote:
Originally posted by Marcus
Leaded petrol is still available, there's a garage near us which sells it. A lot of the classic MG guys go there. But.....it's over 8 quid a gallon!!


Isn't unleaded somewhere near that now anyway!



No but it probably will be next month