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Post by dave1800 on May 22, 2014 12:20:21 GMT
Following on from the thread about the as yet undiagnosed problems with Tommy's new car, I thought it may be helpful if members could confirm:-
(a) whether their cars have cylinder heads modified to run on unleaded fuel and
(b) the extent of the modification valve seat inserts, bronze guides etc;
(c) if running unmodified heads what if any problems they have experienced;
(d) experience good and bad with fuel additives designed to protect unleaded heads
It would be interesting to know how these cars are driven in terms of mileage and maximum speed /RPM limits.
Information on MGB forums seems to be "variable"
Thanks in advance for your help
David
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Post by tommydp on May 22, 2014 22:39:46 GMT
Interesting, Dave!
I've never had a cylinder head modified to run on unleaded, so have been using 98 unleaded with "lead substitute" additives.
Thinking of it, I have absolutely had lots of trouble with these engines after lead petrol disappeared. While running leaded I never had trouble, and hardly ever opened the bonnet for other reasons than checking the oil etc. It's a different story now...
I suppose there could be a link here, as the petrol is the only thing that is different. I don't think my skills have become worse, I believe I should know enough to get these cars going as they should. I was even able to do it when I was 16.
Time to get an unleaded head, perhaps...
Tommy
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Post by indianajones on May 22, 2014 23:10:35 GMT
I can't comment on using leaded fuel as unleaded has been my only choice since driving.
I run RON 95 with 'upper cylinder lube' and she seems to be ok with that.
Lots of different opinions it seems when it comes to the leaded vs unleaded head situation.
-Andrew
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Post by Penguin45 on May 22, 2014 23:30:21 GMT
This is a slightly tricky one. Technically, an un-leaded head conversion involves cutting away the land that the exhaust valve closes on and replacing it with a hardened insert which can take the increased combustion temperatures involved with unleaded petrol. Other things can be done (bronze guides, sodium filled valves etc) but they shouldn't be necessary, strictly speaking. Those of us who have not converted our exhaust valves should be using an additive if the vehicle is doing any significant mileage or regular fast running. This is because the lead coating on the exhaust valve seat will gradually burn away, followed by the valve seat itself. The Federation of British Historic Vehicle Clubs (Which is our representative body in the UK) commissioned independent scientific research some years ago to find approved lead replacement additives. The results can be found in the FBHVC article HERE, as well as up to date info on octane boosters and ethanol. Eugenie's engines have both been leaded heads and I have used the Castrol Valvemaster additive in them both, seemingly with no problems to the head - certainly on the old engine, where no recession was to be found. The new one is behaving, so I'm not taking the head off to find out, as it's just turned about 7k miles. The red one I think is the same. I had quite a chat with Mark (the PO) when I collected the car and I'm fairly sure that he hadn't had the head converted, so Castrol Valvemaster when she's running again. Chris. |
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Post by dave1800 on May 23, 2014 1:04:42 GMT
A very informative website. I recall our late friend "Kels" had a problem with his car not restarting unless he left it for a while after a journey. He suspected vapour lockscovered in the article which points out (the fairly obvious) that this has greater effect on cars with the exhaust and carb on the same side. The Landcrab also may suffer from the fact that the carb feed is sheltered from cooling air by being close to the firewall. I wonder if this is an issue for Tommy to investigate? I would imagine an electric fuel pump pushing the fuel from the rear as Mk1 cars may be less prone to this than later cars with mechanical "sucking" pumps. Any thoughts? David The Federation of British Historic Vehicle Clubs (Which is our representative body in the UK) commissioned independent scientific research some years ago to find approved lead replacement additives. The results can be found in the FBHVC article HERE, as well as up to date info on octane boosters and ethanol. Chris. |
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bandit1
Member
Posts: 34 
Attribute: Technical Expert
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Post by bandit1 on Jul 31, 2014 13:46:22 GMT
One big thing is DO NOT use supermarket fuel, I work on petrol stations and after talking with tanker drivers the supermarket stuff as none or very little additives that help with octain and cleaning !!! thats why its cheaper, modern cars can tolerate it but our classics are another story ! I would personally go for an unleaded head but saying that if you dont do many miles per year and only " Pootle " about, then you would get away with a decent additive, my own preference being Castrol valvemaster plus, ta.
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