unleaded Petrol

[triman65]

I am thinking of buying a classic Bonneville about 1973 and I have heard you need additives to be able to run them without causing damage to valves and valve seats. Can any one advise me on what additives are best. Any help would be appreciated.

[thunderbird]

redex do an additive for lead and octane boost,but running an older vehicle on unleaded only really causes more rapid ware on cast iron heads where the seats are cut directly into the cast iron and then its only exhaust valves that are effected due to the higher tempretures around them, with an alloy head that has steel valve seat inserts the extra ware is likely to be a lot less unless you are riding a lot harder or doing excessive milages.hope this helps cheers steve

[L.A.B.]

All the original hype about unleaded petrol causing massively accelerated valve seat wear appears to have turned out to be somewhat of a myth, as many classic owners have found that additives are generally unnecessary, although there's nothing to stop you using them (just don't mix them) if you want?

I've used additives such as Castrol Valvemaster Plus before, but I suspect that I could have been wasting my money by buying it?

Some of these additives also contain octane boosters such as Valvemaster Plus, but I can't say I've  noticed any difference if I don't use it, so unless an engine was fitted with high compression pistons, the octane boosters in these products may be of no benefit, that is, if they actually work at all?

Castrol Valvemaster http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_166596_langId_-1_categoryId_165750


Valvemaster Plus http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_166547_langId_-1_categoryId_165750
 

[Goldy]

I remember when leaded petrol first became unavailable I was talking to a retired motor engineer about it. He said if you intend to race the engine and do high milage then you need to do something about it, but for the average classis car or bike don't worry about it.

[triman65]

Thankyou all for the information and will think about it.

mick

[Goldie]

I tend to put a drop of good old RedX in my Goldies, and buy the highest octane available at the pumps, which is normally 97.

Every so often i put an egg cup full of Castrol R 30 in the tank, just to give that lovely smell.

[henry_norton]

I remember when unleaded was first introduced people were getting all sorts of things done to their engines like retarding the ignition by 3 degrees and one tank of leaded to every three unleaded (obviously the days before factory fitted catalytic converters!). They seemed terrified of this new fangled engine destroying fuel. I run my Bonneville on bog standard unleaded and it hasn't worn out yet....  

[twolitre]

The biggest worry about using unleaded petrol on older vehicles is that  some of the plastic pipes and parts used on carbs. etc. at that time can soften and fail.
  My company ran a fleet of taxis on propane (an unleaded fuel) back in the late 1970s and 80s. Mostly BMC 1800s (Land Crabs) and Cortinas.  We NEVER had to strip an engine for valve pocketing although the seats were cast iron, though over the typical 200,000 mile life of an engine we did find the valve clearances sometimes needed opening up by the odd thou. during normal servicing.
  I have rarely used anything other than unleaded petrol in my own cars or motorbikes since it was introduced.  Retarding the ignition slightly was necessary at first because unleaded initially had a low Octane Rating.  Now 97 Octane is available that is no longer necessary.
  From long experience, my advice is use unleaded without fear.  If the valve clearances do start to close up significantly, it will not be for MANY thousands of miles and by then you will have saved enough money to pay for insert fitting many times over!  My 1968  Triumph 2000 (car) engine is now knocking up about 150,000 miles, about half of that on unleaded.  I have never had to open up the rocker clearances.
  By the way, I have never suffered any plastic problems, but I know some people who have.

As L.A.B. says the scares never materialised.

If I can quote Canley Classics (Triumph car specialists) from their Website :-  "The best way to convert your Triumph to unleaded is to fill the tank with it".  And I totally agree!

Jim.

[henry_norton]

Hear Hear Jim. I've carried out that conversion too! With regard the octane rating of unleaded I have always used the bog standard cheap(er) variety in my relatively high compression engine (9:1) and it works fine - no pinking or anything like that. I thought super unleaded was just a way to make extra money out of Subaru Impreza owners....

[Goldie]

We have 2 or 3 garages in Cornwall that still stock 4 star leaded fuel, but i was told to be wary of it is because, even though the tanks get refilled from time to time, the chances of getting fresh fuel is rare, as not many people use it because it has gone stale being in the tanks for a long time, and older engines may not perform as they should

[twolitre]

Thanks for the support Henry.  I use ordinary unleaded in my 1959 Speed Twin with no pinking or problems, but the 2004 Kawasaki W650 I use on touring holidays (mainly because should spares be needed I would not have to sit on a grass verge waiting for a mail order delivery), suffers the 'tinkle' associated with that engine.   I am not sure it is pinking, but 97 octane seems to reduce it.  The curious thing is that this engine was presumably designed to run on 95 octane unleaded.
  My Triumph 2000 car engine on the other hand, is from a Vitesse Mark 2 and was designed to run on 100 octane (5 Star) and had to be retarded, with some loss of power, to prevent pinking loads damaging the crankshaft bearings.  It now runs quite happily on 97 octane with normal ignition setting and no pinking.  It is fitted in a Gentry MGTF Midget replica and can quite easily outrun most modern cars up to the Legal Limit.
  Incidentally, as an apprentice I learnt that normal big end loads were normally less than 2 tons/square inch.  Pinking (and pre-ignition) can take those loads to over 4 tons/square inch.  Persisting with any petrol which produces pinking should be avoided at all costs unless you like replacing main and big end bearings.

An addition for Goldie: I too am a retired Motor Engineer.  I used to be able to add T. Eng., L.A.E., M.I.M.I.  after my name.  However the Institute required a yearly subscription to retain Membership and I could see no valid reason for the continued expense.  I do still have a 'full set' of relevent City and Guilds Certificates and a National Craftsmens' Certificate.  But I must admit that the vast majority of my experience is on vehicles with more than two wheels.  Being without a motorbike for almost 50 years I am still adapting to some of the differences in motorbike engineering, though many (most?) principles are shared with cars etc.