Leaded/Unleaded?

[Tornado]

Seems there is lots of gnashing of teeth and wringing of hands over on the classic mini forum on using older original iron heads meant for leaded fuel with modern unleaded without doing a valve seat replacement to harder seats.
Why do we not hear such concerns on our Commandos?

 

[EstuaryBoy]

You would have done 20-30 years ago when unleaded was first mooted here in the UK. I (like many, I suspect), had the P11 seats replaced.
I seem to recall it may have been unnecessary, as most alloy heads had harder seats as standard, and as Germany was using unleaded very early the Nortons sold there appeared to have no problems..
Some researchers did valve recession measurements after the fact on heads deemed 'unsuitable', and extremely high mileages were required before problems arose.

 

[kommando]

Why do we not hear such concerns on our Commandos?

Because on a Commando its an aluminium head fitted with hardened seats, same with all Brit bikes with alloy heads. They were not daft.

There were scammers around when unleaded first came to the UK saying all seats needed changing but it was just a way to drum up business. Only iron heads had the issue.

 

[EstuaryBoy]

Because on a Commando its an aluminium head fitted with hardened seats, same with all Brit bikes with alloy heads. They were not daft.

There were scammers around when unleaded first came to the UK saying all seats needed changing but it was just a way to drum up business. Only iron heads had the issue.

I think even the reputable businesses were offering the service rather than miss out on the hysteria surrounding the change..

 

[Fast Eddie]

Wasn’t always the businesses fault, I know two very reputable guys who did a lot of them because the CUSTOMERS insisted, even against the business guys advice!

 

[Tornado]

So the mini chaps are thinking their original valve seats are not up to the task without leaded fuel? I'll try to find more details on this over there....

 

[Fast Eddie]

IIRC you need very sustained, very high speed for it to be an issue. This either wasn’t known at the time or folk overlooked it. Not many riders / drivers of classic vehicles subject their P&J to that anyway.

And even if they did, something would no doubt let go first !!

 

[EstuaryBoy]

I do see similarities with the current E5/E10 issue, where 'X' is the unknown so the worst case scenario always prevails. Many assumed their valves would bury their way through the engine and pop out through the top in next to no time, hindsight assures us this was hardly the case....

 

[kommando]

So the mini chaps are thinking their original valve seats are not up to the task without leaded fuel?

Iron heads did not have hardened seats unless they were going to an unleaded country, when UK unleaded was planned then it made sense for Mini iron heads to get hardened seats from that point. So depends on the age of the head and how the car is driven.

 

[Tornado]

Iron heads did not have hardened seats unless they were going to an unleaded country, when UK unleaded was planned then it made sense for Mini iron heads to get hardened seats from that point. So depends on the age of the head and how the car is driven.

Ah Ha, so there were no seating inserts present, just relying on the cast iron cut in the head. That makes more sense now.

Found this video on fitment of mini head exhaust seats and flow bench testing following 3 angle seat cutting vs stock...

 

[EstuaryBoy]

Mind you, back then this discussion would have taken place in your club magazine....
(Stay tuned for next month's... or quarter's.... episode!)

 

[kommando]

Ah Ha, so there were no seating inserts present, just relying on the cast iron cut in the head.

That's how it worked, and when all fuel was leaded the cast iron seat lasted until the engine needed an overhaul.

 

[MexicoMike]

IMO the concern is overdone. I never changed the valve seats on several old muscle cars, one of which did over 100k miles plus weekends at the drag strip on unleaded fuel and no sign at all of valve seat issues...

 

[Dan1950]

I started running AMOCO unleaded premium in my A65T in the mid '70s when I saw how much carbon build up there was when running Sunoco 260. I discovered this after I pulled the head with very few miles after a top end job.. I also ran the same fuel in my '64 Panhead that had brass valve seats. I did use Marvel mystery oil in the Panhead due to the steel valve guides.