Unleaded Petrol

[998auto]

Not sure if this is the right section but hey petrol is a fluid.

Anybody know how to convert a leaded engine to an unleaded engine?

Is it any different on an auto?

[asahartz]

No, it's exactly the same. remove the head and strip it, then take it to a machine shop for them to fit hardened valve seats.

FWIW I just run mine on unleaded anyway. 250 miles a week and I have yet to see any ill-effects on any of my Minis. (I do have two spare heads in the shed and a nephew who runs a head machining business if things should ever go wrong!)

[mollymoke]

The difference as I understand is the hardness of the valve seats, I think particularly the exhaust valve seats.
The unleaded fuel burns the older soft valve seats, so you need to have your head refurbished with new hardened valve seats.
This should not impact on auto/manual, but I still use hi-octane fuel so you only save the expense and hassle of upper cylinder lub.

[998auto]

Cool I have a manual engine in the garage which I think is unleaded. I may just take the head of that.

Any ideas on how you tell whether an engine is unleaded?

[mrslaphead]

I too was running a leaded head on unleaded, an mg metro head on an spi block.
Mine lasted about 18 months and has just been refitted after having new valves and seats fitted.
It had burnt out two of the valves and worn away all 4 seats. According to Calver (I think) heads develop a kind
of lead memory which lasts for a period of time after which damage can occur.
I also believe that long periods of motorway (high revs) driving can be unhelpful.
I just wish I had thought to check if it was leaded or unleaded before I fitted it the first time.

[notamini]

Careful with that swap! I'm not positive but the auto and manual heads may not match up. Or is it just the block to the transmission?

[dan]

heads are the same, it the block and 'box that dont go together to easy

[998auto]

Good stuff.

I will let everybody know how I get on.

[notamini]

Thanks Dan. Wasn't 100% about that.

[asahartz]

May 3, 2010 22:57:55 GMT mrslaphead said:

I also believe that long periods of motorway (high revs) driving can be unhelpful.

Probably so - my route doesn't involve any of that. In fact in my daily 25 miles, there's one stretch of about two miles where I can get to 70mph if the traffic lets me, and that's it.

[mrslaphead]

I was doing 60 miles a day, approx 55 of them on motorways.
With the exception of the M65 to M6 south slip road it isnt much fun.

[golly]

Why go to all the bother of changing heads. Golly-gosh, my 85 manual mini has a leaded engine and i just put some addative into the tank every time I fill up. It's not expensive and a bottle lasts me for ages. I have no intension to change.

[dan]

something like this cgi.ebay.co.uk/TEXACO-LEAD-SUBSTITUTE-FUEL-ADDITIVE-BOXED-12-X-500ML-/180493061394?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2a06398d12

[mrslaphead]

Which wouldnt work with spis as it says not to be used with cars with catalytic converters.

[dan]

sorry didnt read that but something similar will do the job

[mrslaphead]

To be honest the head that was originally on the car is unleaded.
I then bought an "uprated" head and didnt consider that it wouldnt be unleaded.
It is only due to burning out two of the valves and all 4 seats that I did the conversion.
I dont think those additives would have helped once I discovered the error.

[jockduck]

I burned out more exhaust valves in the days of leaded fuel. I use ordinary unleaded without a additive no problems.

Jock

[Holly]

May 8, 2010 11:29:17 GMT jockduck said:

I use ordinary unleaded without a additive no problems.

Me too, i have in my van for the past 2 years and my shorty for the past 4 years and have had no problems so far

[mrslaphead]

I was running ordinary unleaded without an additive and the head lasted 18 months.

[Admin/Founder 2]

its down to individual judgment really?
If you would like to change to Hardened Valves on the Cheap you could always look around Scrap yards for a Later Mini,Metro,or Maestro A series that has a head already suitable for Unleaded Petrol

Its hard for me say what id do as my previous mini 10 years ago was a 1977 and had its original head but you could still buy LRP/4 star back then,and Boris Being a 1995 can take Unleaded

Ive heard plenty say though that using Unleaded on a non unleaded car hasn't caused them any problems whatsoever

[998auto]

As I already have a spare head I may just give it a go.

It will give me the opportunity to check on the state of the engine as well.

[notamini]

That brings up a new question. Will an A+ head fit the A engine?

[mollymoke]

I'm not sure about the A+ vs A head, but externally, you may need to fit a temp sender unit, the hole in the A+ is probably blanked off. I just drilled and tapped mine to suit as I have the old wiring loom and gauge.

[998auto]

Not thought about that. I will have to compare the two.

Any other differences to consider?


Anyway confirmed the engine in my garage is an unleaded A+ by using this cool site,

www.guess-works.com/Gearbox/Technical/engine.htm

[asahartz]

Yes it'll fit. No the temperature sender isn't blanked off - maybe on the injection engines, but not on the carby version.

[998auto]

Good stuff. Its definately a carb engine.

[notamini]

8-)Thanks much.
I can really use this some day since there are so many Metros and the like. Plus mine is an original leaded 1275. Again, the engine site will not work for my line of cars. 12H292B-H4409.
The 292 isn't on the list.

[998auto]

Might need to start a new posting for this but give the following site a try,

www.a-serious.com/forums/