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Petrol - Leaded Or Unleaded?


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#1 clarks.2006

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Posted 02 October 2005 - 10:34 PM

I have a 998cc 1985 Mini Mayfair and im not sure wether it has got a leaded or unleaded head in it. Would it harm it if i put unleaded petrol in a leaded engine, and what harm can be done? Thanks for your help greatly appreciated Clarks.2006 :grin:

#2 Guess-Works.com

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Posted 03 October 2005 - 08:39 AM

the likelyhood is that '85 is a leaded engine, if it is the original engine, but as leaded petrol has not been available for sometime, you'll have to put unleaded in it anyway, but you will also need to use an additive.... I suggest Castrol Valve Master, out of all the ones I've tried that's the best, and the few extra pennies for the "Plus" version which has a octane booster in it will also help you cars running...

Whatever you do dont be fooled that LRP ( which will is also being phased out ) it leaded petrol, it is not... and not 1/2 as good as std unleaded with an additive.

I believe the earliest engine fitted with an unleaded head were numbered 99HD81, anything later than that should be running unleaded.

#3 Mayfair85

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Posted 10 February 2008 - 01:13 AM

I think more detail is needed here.

How can I tell if my head is for leaded or unleaded exactly? I've been running it on Unleaded simply because thats what the guy who sold it to me used. What would I notice different if I should be using an additive?

Any help would be greatly appreciated.

Edited by Mayfair85, 10 February 2008 - 01:18 AM.


#4 iansmini

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Posted 10 February 2008 - 01:22 AM

the likelyhood is that '85 is a leaded engine, if it is the original engine, but as leaded petrol has not been available for sometime, you'll have to put unleaded in it anyway, but you will also need to use an additive.... I suggest Castrol Valve Master, out of all the ones I've tried that's the best, and the few extra pennies for the "Plus" version which has a octane booster in it will also help you cars running...

Whatever you do dont be fooled that LRP ( which will is also being phased out ) it leaded petrol, it is not... and not 1/2 as good as std unleaded with an additive.

I believe the earliest engine fitted with an unleaded head were numbered 99HD81, anything later than that should be running unleaded.


am confused by that i have an engine with the numbers 99HD1 but you both state unleaded is that correct or should on be leaded?

#5 CHARLIE530

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Posted 21 February 2008 - 01:39 AM

im currently running a 1992 unleaded 1998. im about to put a 1275 mg metro engine in it, engine number : 12HD24012O736 ands its an 88'.

is it likely to be a leaded or an unleaded

any help would be greatly appreciated.


cheers charlie

#6 Pie

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Posted 21 February 2008 - 12:23 PM

As guessworks has said, if its an original engine the chances are is a leaded head. If the had has been modified at all then it is possible that its had hardend valve seats.

Guessworks also said that he lieved that the earliest engine fitted with an unleaded head were numbered 99HD81, anything later than that should be running unleaded.

So look on the engine and see if the engine number starts with 99HD81.

#7 Big Man

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Posted 21 February 2008 - 12:31 PM

If in any doubt use valve master or similar as apparently it does not hurt a unleaded engine but protects a leaded engine.

chers

bm

#8 Ethel

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Posted 21 February 2008 - 01:04 PM

The odd tank of unleaded won't hurt - unless the reduced octane causes your highly tuned engine to detonate.

There's no way to tell for sure your head is unleaded short of taking it off and examining the valve seats.

#9 Danny3320

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Posted 18 May 2008 - 07:39 PM

hi i have been told my engine is a leaded just want to check if he is correct dont want to strip the engine down and replace bits and it be wrong

my engine number is 99HB81PO112799

Thanks

Danny

Edited by Danny3320, 19 May 2008 - 08:54 PM.


#10 XxsarahxX

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Posted 13 June 2008 - 05:47 PM

hey im hopefully next week getting a 1981 mini and i think it will probs run on leaded petrol, do u know how much it will cost to get it changed to run on unleaded, and is it better to do that than keep adding the castrol valve stuff?

#11 Down&Out

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Posted 14 June 2008 - 05:59 PM

i think you have to change the head to an unleaded one. they cost around £250

#12 XxsarahxX

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Posted 14 June 2008 - 11:21 PM

i think you have to change the head to an unleaded one. they cost around £250

thanks! i think if it hasnt been converted it will probs be best to have it done straight away, hopefully it will be and ill save some money...

#13 roofless

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Posted 14 June 2008 - 11:57 PM

i think you have to change the head to an unleaded one. they cost around £250

thanks! i think if it hasnt been converted it will probs be best to have it done straight away, hopefully it will be and ill save some money...


if its been used even remotely in the last 10 years I'd be surprised if it hasnt already been converted.

#14 XxsarahxX

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Posted 15 June 2008 - 10:50 AM

ooh well hopefully it has ^__-

#15 Down&Out

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Posted 15 June 2008 - 10:53 AM

i think you have to change the head to an unleaded one. they cost around £250

thanks! i think if it hasnt been converted it will probs be best to have it done straight away, hopefully it will be and ill save some money...


if its been used even remotely in the last 10 years I'd be surprised if it hasnt already been converted.

both of mine where used as dailys by the previous owners and are still on leaded :D




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