unleaded fuel

#2
Don't know about that john but in addition to your question I would like to know if anyone has experience of using these inline catalyst contraptions such as spitfire advertised on eBay?
If they do what they say on the tin they are a godsend for us old folks on the cusp of Alzheimer's
 

PeterZRH

Well-Known Member
#3
Don't know about that john but in addition to your question I would like to know if anyone has experience of using these inline catalyst contraptions such as spitfire advertised on eBay?
If they do what they say on the tin they are a godsend for us old folks on the cusp of Alzheimer's

There is no such thing as a "fuel catalyst" which works. Lead or additives work in two ways, they either coat the valve/seat, cushioning and protecting them and/or they change the combustion characteristics to protect the valves and seat. There is no catalytic process that can do this. This is the EXHAUST valve only.

AFAIK, there is no way to ensure an engine not designed for unleaded to work long term safely with unleaded other than machine the seats to a compatible material and in some case the valve too need to be a different material. I'm not sure about TC valves but as some are rumoured to be made of cheese, better quality versions might not be a bad idea anyway. There are exceptions to this including the RV8 as these have separate seats (the alloy heads are too soft and hence need an insert) which happen to be the right materials. Even then, "officially" only SD1 engines and later are guaranteed to by unleaded friendly - but there seems to be no different to earlier motors and these were sold in the US at a time when unleaded was sold.

What you will find is that lead or additive builds up on the valve seat so you might get some short term protection until it is burned or worn off. You cannot rely on this and valve damage can happen frighteningly quickly, like a few hundred mile if you are unlucky.

Use a additive of proven effectiveness or better get the head done.
 

Dave3066

Well-Known Member
#5
4 pot heads are alloy too so already have hardened valve seats. That said, I have seen some quite severe seat recession in 4 pot heads. I would certainly use an additive as well as using the highest octane fuel you can find, I use Tesco Momentum (waits for the howls of derision at the use of supermarket fuel). Despite all this, I have suffered repeated valve damage to exhaust valves that have got too hot and melted away in places. I suspect I do a lot more mileage in my car than most. I would take every precaution you can, but be prepared for some long term damage simply due to the fact that these engines do not like modern fuels.

Dave
 
#6
The 4 cyl engines suffered burnt valves on leaded fuel too. Other than not being able to get sufficiently high octane fuel to run the 10:1 engine without some de-tuning, I've not seen any bad effects of unleaded on these engines.

Yours
Vern
 
#7
I suggest running Flash Lube or Morey's upper cylinder lubricant, and checking the valve clearances every 20000 miles, instead of every 40000 miles, and adjusting if needed.
Flashlube and Morey's were both made so motors running on liquified petroleum gas (a mix of Butane and Propane) could run without valve damage. So it should achieve the same thing.
I checked my valve clearances at the start of summer, for the first time in 8 years. They were still to spec. I was very happy about that. I use Flashlube in the US, mainly due to availability. Morey's on my Rover in Australia.
Also play close attention to your cooling system, so things do not run too hot. If the heads get too hot, they tend to puke out the valve inserts, which is very inconvenient.

James.
 
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