dondon wrote:
well i couldnt help it...
i just got my car recently,and have been thinking about the same debate going on here too... i guess you guys know im still new to this experience...
what is the verdict?does it run on unleaded(purely) or
leaded(unleaded with lead addictive)?
in the past there wasnt any unleaded for these beauties,so the only option is for you to buy a lead addictive(like a converter)so that it runs smoothly...(thats my understanding.)
so what is going on?please explain....and what happens if you dont add the addictive?
OK.. what happened is- way back, when most cars had cast iron heads (like a Mini) and crap valves, they had already put lead in the fuel to improve the octane rating. They found that the lead salts produced coated and protected the valves and `seats' in the head, it acted as a high temp lubricant.
Cast iron is basically a mixture of iron and carbon (in the form of graphite flakes).
Without any lead or substitute, the red hot exhaust valves micro-weld to the iron particles in the head, and this can pull chunks out of it over time which is known as valve seat recession.
Even many cars with alloy heads (eg Jaguar) had valve seats made of cast iron, well into the 70s or later.
Additives such as Flashlube or Redline lead substitute or Valvemaster act to prevent this microwelding.
It is true that an old car, run for years on leaded fuel, can use unleaded without additive for general running about, (for a while) IF it is not disturbed. But the minute you reface the valves and seats you run the risk of rapid valve seat wear. See my pic above.
OTOH, after 30,000 miles in my 1310 using Flashlube I stripped it for a look- the seats were shiny and the S/S valves were not worn. I gave it a quick lap in and put it back together.
BTW I can't fit unleaded seats in this head as the exhaust valves are too BIG...

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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.
