You will always get a yes and no answer to the lead substitute debate. I use it in my Cooper S. I have not data on if it helps or not but i dont want to take the chance. I only do low km so the cost is negligible. I did use a cap of 2 stroke oil when unleaded first started and before i found lead substitutes.

Some guys over here run 98 with no lead substitute and have no problems. If i had a daily driver doing high kms i would run it until my next rebuild then change to unleaded seats.

Thank you very much

_________________
1973 Clubman GT - YG2S8 1637

Assuming you have have hardened valve seats fitted there is no need for a lead based i.e. TEL additive. They were/ are? used to boost the octane rating of the fuel. My engine has a compression ratio of 11:1 and I have no issues running pump fuel, this included the time I drove the car in Indonesia (I did carry octane booster with me but never had to use it). I choose to use 98 RON fuel but can get away with 95 RON.

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

IMHO a basic 6ES plug will last basically forever in a normal road engine that is any sort of reasonable tune... Unlike some cars, a Mini engine in any reasonable state of tune doesn't eat plugs.

And the second question is pretty much ..how long is a piece of string..... A 73 GT should be quite happy with 87 (US) octane... but it pretty much depends on the state of tune.

Many people will tell you that 93 to 1 compression ratios require X octane .. but that's a pretty useless statement. Your engines octane demand depends on its operating compression; not the static ratio you measure when the engine is being built. This operating compression is determined by a whole host of factors including things like the static compression, how well the head and carbs flow air, what kind of cam you have, what revs you're running at etc etc.

So the answer is... does it ping? If it does then a higher octane fuel MAY (but not not necessarily) help. But it is worth trying because you DO NOT WANT the engine to ping.. Try the 87 and if it pings move up to the 91. Excess octane does absolutely nothing for you except drain your wallet.

As to the second part of the question... should I use a lead substitute? The answer is pretty much ..Yes.

Lead in fuel does 2 things; it raises the octane rating and lubricates and protects the valve seats in iron heads.... like that fitted to your GT. You can get products that do one or the other ..or both. You need one that will protect the valve seats ..and you may benefit from the increased octane.

Many years ago when leaded fuel was being phased out in Oz (and other places) BP ran some technical seminars where they reported on testing they did in the UK. Usefully for us they used an A series in a Metro as a test mule. They sent the Metro off on a series of test runs on the motorways and found that, if kept below about 3000 rpm, the removal of lead had little or no bad effect. However, if run at substantially more than 3K for extended periods, the engine was trashed in about 10,000miles...

You pays your money and takes your chances.....

Cheers, Ian

"Many years ago when leaded fuel was being phased out in Oz (and other places) BP ran some technical seminars where they reported on testing they did in the UK. Usefully for us they used an A series in a Metro as a test mule. They sent the Metro off on a series of test runs on the motorways and found that, if kept below about 3000 rpm, the removal of lead had little or no bad effect. However, if run at substantially more than 3K for extended periods, the engine was trashed in about 10,000miles... "

Well, about the time this was going on it was realised that hardened valve seats were necessary to avoid exactly this problem (valve seat recession) so for decades now hardened seats have been fitted as a matter of course during overhaul. So unless GuamMini's cylinder head is stock standard from the early 1970's, there is no need to add a TEL additive for its lubricant properties. As you already pointed out, it's extremely unlikely it is needed to boost the octane rating of the fuel...

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Think your timings a bit out there.... it wasn't until 86 that new cars were required to be built to take unleaded fuel and leaded didn't disappear until 2002...

If Jim's happy he has hardened seats then he won't need a lead replacement...

Or he could just choose to gamble..

Cheers, Ian

No, my timing in not out. I was a Petroleum Chemist working for Shell in 1986 when ULP was introduced, reread my post above. I went on to operate, maintain, overhaul and train people to use octane engines for 20 years so I guess I know a bit about what I'm talking about. If you have any questions I'm happy to discuss...

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

I recut the valve seats in a 998 head 20 years ago, put it on my son's clubby for 6 months and he drove it as usual ( like he stole it).
It then had serious valve recession, 'seats' were rough as the hot valves had pulled metal out.
OTOH on my 1360's head the valves and 'seats' were shiny after 15,000 miles when using Flashlube.
Dunno what's in it but it works.

There are still many A series heads being reconditioned without hardened seats being fitted. Many racers don't trust that they won't come loose. There are right and wrong ways to fit inserts.
Edit- for clarity.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

From what I was told my GT has the stock valve seats. I am going to try and use a lead additive. Nothing to loose at this point. I might replace the head soon with something that has hardened seats for unleaded fuel. Thanks everyone for a wealth of knowledge

_________________
1973 Clubman GT - YG2S8 1637

Might be difficult to get hold of a lead (TEL) based additive. I think the ones available usually use MMT, a Manganese organo metallic compound. Performs similar to TEL.

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Manganese ones like Valvemaster crap up the plugs and ports. I used it for a short time, never again.
I'd import some Flashlube it's made here in Sydney.
Originally designed for taxis running iron heads and LPG. Which have the same seat recession problem.

https://flashlube.com/en/where-to-buy-flashlube.html

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Here in the US the additive is by a company called gunk and they said to put a whole bottle and filling yup the tank after. I will give this a try.....

_________________
1973 Clubman GT - YG2S8 1637

Gunk...

https://www.autobarn.net/chm37-12.html

https://www.bobistheoilguy.com/forums/u ... ber=866488

_________________
"Show me the Mini!"

From the Gunk Valve Medic MSDS;




COMPOSITION/INFORMATION ON INGREDIENTS
Ingredients CAS # Wt.%
Petroleum distillates 68476-34-6
85.00 - 95.00
Distillates (petroleum), hydrotreated heavy 64742-52-5
naphthenic 7.00 - 13.00
Solvent refined heavy paraffinic distillate 64741-88-4
0.10 - 1.00
Naphthalene 91-20-3
0.10 - 1.00
Xylene 1330-20-7
0.10 - 1.00


I fail to see any ingredient in that lot that would reduce valve seat recession. It's all just hydrocarbons, personally I wouldn't bother. Waste of money..

Edit: Just read Gunk doesn't claim this stuff will prevent valve seat recession. They claim it's to dissolve sludge, gum and deposits only...

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Plenty of snake oil salesmen in the days of wild west of the USA.
It appears nothing has changed.........

_________________
1967 Cooper S - new front bearings to do.
1965 Cooper S shell - all painted up, ready for fit out.
1969 Cooper S Mk2 - claimed by 2nd. born
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.