lead subsitute?

[moggymaniac]

hi guys, so as a result of my forgetfulness to put lead substitute additive in every time i fill up, i am now having to regrind my valve seats, and possibly will need a new head. SO, i've heard talk of 'magic beans' of some description that you put in the fuel tank and they have a life time garantee, as my boss has done with his minor, but he didnt know what exactly they were as it was restored/prepared to drive for him. surely these 'magic beans' as he called them are too good to be true? do they exist? and do they WORK?

[bmcecosse]

There is NO need for so called 'lead substitute' - and certainly there are no 'magic beans' .......... The A series engine runs just fine on unleaded fuel - unless you are constantly hammering it on the Mway. Just set the exhausts to 15 thou clearance, leave the inlets at 12. Even in the days of leaded fuel -exhaust seats had to be reground from time to time! Check/reset the gaps every 3000 miles - they will be fine. If constantly running hard/long distances - then you could either fit an 'unleaded' head with hardened seats and valves, or use Tetraboost which is the ONLY additive that actually contains Tetraethyl Lead, and therefore converts unleaded fuel into leaded fuel! The other additives contain various mixes of sodium/potassium compounds and a large dollop of mystique! They often boost the Octane rating slightly so preventing the 'pinking' that straight unleaded fuel may perhaps cause, and so in this sense only they are perhaps of very slight benefit - but - it is very simple to reduce the ignition advance very slightly, which gives a permanent cure, at no cost!

[moggymaniac]

thanks for the advice. well the engine has seen long motorway driving and i have a 4 branch racing exhaust and 1 3/4 SU on it for a bit more go, would this increase the chance of wearing the valve seats faster?

[alanworland]

Practical Classics a few years ago did some tests of 'lead subsitutes' one type was the sort you describe.
Some worked in preventing the exhaust valve 'welding' itself to its seat, some didn't. Castrol Valvemaster worked, Millers worked and I seem to remember about 4 or 5 others also worked including Tetraboost, but bits of lead or tin in the fuel tank didn't!
Catastrophic valve seat recession occured and the head was scrapped - B Series engine.
I use the Castrol and have not noticed any closing up of valve clearances (so far!)

[bmcecosse]

Well - if driving it hard and long - probably best to get hold of an unleaded head. What engine is it ?? Late standard Mini 998 heads are 'unleaded' (but don't actually have hardened seats!!) and are fine on 948 engines. Later 1275 heads (12G940) are unleaded (and DO have hard seats) and can be fitted to 1098 engines and obviously fit 1275 engines. Certainly don't pay fancy money for either!

[moggymaniac]

yes ive been looking at 12g940s on ebay recently, they seem to be going for quite a bit at the moment but i havent had the guts to buy one yet :p it's a 1098, and am i right in thinking that the large valve version of the 12g940 would be too much for the 1098? whats the best head for power that requires the least work to fit? i am aware of the possibly needed recession of the exhaust valves into the head as not to hit the block..i would deal with it as it comes. just out of interest eventually i'd like a vmaxscart supercharger kit on a 1275 engine but i am currently a student so its nothing but a dream, i'm for affordable slight performance

[bmcecosse]

A standard 940 head is the way to go - although the 'big valve' would work - it's really not necessary on a 1098.

[Pyoor_Kate]

..or you can pick up an A-Series metro head, lots of them were unleaded (if you dink around the internet you'll find a page with a list of A-series unleaded heads).

..or get hardened valve seats fitted. Living in Slough where everything is ridiculously expensive (being near London) and people are unclear on what a classic car is, therefore get scared and charge even more, and me being a girl, I still got my Viva's head skimmed, new valve seats (hardened), generally reconditioned and returned to me looking like new for 150...

iirc, they fitted it too.