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MG TD TF 1500 - Unleaded fuel

Is it really necessary to use an unleaded fuel additive? I have read (heard?) that after an engine is run on leaded fuel for some time the valves and seats become hardened (the purpose for lead in the fuel in the first place) and it isn't necessary to use an additive with unleaded fuel.
R. J. Lowery

Hi
There was a long thread in this about a month ago (oct.19th) on a similar question that I asked.
No need to start all over again
Erik
Erik vanHardeveld

Bob,

Here's the thread to which Erik is referring:- http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=archiveth&archiveyear=8_2005.dat&access=&subject=8&subjectar=8&source=T&thread=2005100423053130028

I can tell you from personal experience (not mine) that you can damage the valve seats.

It depends on the mileage (kilometrage?) one drives. Strictly a guess, but probably 500 miles (800 Kms) a summer would justify keeping some lead additive in the car. In my case, I drive at least 4,000 miles (actually 6,400 KMs) a summer, so I installed the stainless seats in the most recent rebuild and I've not had to ever think about it again.

Gord Clark
Rockburn, Qu.

Gordon A. Clark

lead was only added to boost octane. there have been various anecdotal tales about lead preventing valve seat recession, but reputable organizations have done road tests and found no factual evidence that valve seat recession is the result of unleaded fuel. save your cash and just drive your car. tom
tm peterson

When did they stop selling leaded fuel in the US?

V.W. Piņa

The elimination of lead in automobile fuel was started in 1975 and phased in through 1986 in the US.
Dallas Congleton

They haven't, it is still used in aviation fuel 100 octane (blue) low lead (although at a lower concentration than was previously available in 80 octane leaded (red)). The fuels are tinted so the pilot can tell which is in the aircraft, as the more commonly available Jet-A feels different and smells different, but earlier engines designed to run on 80 leaded would do quite poorly on 100 low lead.

Also, some fueling stations have the old leaded pumps for off road use only, or in certain collector type vehicles. This varies from state to state. The little independent in my town used to have it until a year ago.

warmly,
dave
Dave Braun

Correction Dave B. The 100LL aviation fuel has twice the lead content of 80 Octane aviation fuel but about half of the old 130 octane (wow, remember that stuff?)green avgas. Aircraft engines designed for 80 octane are indeed having problems from using 100LL but it is spark plug fouling from the extra lead. 80 Aviation has the same amount of lead as the old leaded regular auto fuel however it is becoming very difficult to find. I have mixed 100LL aviation with 87 Unleaded auto fuel to run in airplanes (that are approved for auto fuel) that have engines designed for 80 octane leaded avgas just to get the lead content correct. It works great. I have a friend with a XKE who does this routinely mixing with 91 octane auto fuel to get the lead and octane up and I occasionally mix a gallon or two of avgas with the balance in unleaded regular auto fuel on my TF. For the TF it's probably not necessary for the octane boost but I'm not sure if the rebuild used valves and seats for unleaded fuel.

There have been changes in valve seat and guide materials in aircraft engines to allow the use of unleaded fuel.

Aviation fuel has an extremely long shelf life (years) and is great for your non catalytic mower and cycle type engines for that last tank before Winter storage. First pull starts in the Spring. I use Stabil for the cars after filling the tank.
D Clark

Dave
Won't it bu**er up the TF"s Cat????
J James

Ahhh ..the never ending saga of lead additives! I think this was one of the first questions I ever asked when I purchased the TF and first found this BBS!
Looks like all still have "mixed" feelings here. I stuck with the lead additive for years because there were several empty cans of it in the car when I purchased it. When I had the engine re-built this year it was the first question I asked the fellow that did the re-build...(he said I would no longer need it).
Previous to this year...I would take the car up to National Trails Drag Strip (lucky for me I live close to there) a few times a year and fill up with leaded fuel. I always made sure this was what was in her for "hibernation" and she alawys fired right up over the winter months. Thanks to all those "T" owners out there "painting their cars" our winters have not been as bad around here as they used to be, (LOL), so I have been able to get out for more runs in the winter!
Looks like this is a subject that will never be "settled" for sure...(too many variables!?) ...I will say from my early recollections as a child that the Ford Tri-Motor I rode in from a barn near Columbus to Clevland,OH did not seem to like auto gas..but that is another story!
Cheers,
David 55 TF1500 #7427
David Sheward

When I was in NJ, I lived down the street from a small airport using airport transfers tonbridge. I ran 100LL exclusively in the B for 10 years, she hates anything else! In the TD I mixed 100LL with 91 unleaded (25% 100LL) and the car ran great! Aside from the raise in Octane, the lead had a profound cooling on the valves & engine. Now that I'm no longer next to an airport, I run a pure lead additve in both cars...the B because it was designed to run on a minimum of 98 Octane, and the TD for the valve cooling, which comes in handy when the temp is 3 digits.JMHO.
http://www.kemcooil.com/product_info.php?pId=61
Robert Dougherty

robert, where do i find information on how an anti knock compound cools valves? thanks, to
tm peterson

"Dave
Won't it bu**er up the TF"s Cat????" (JJ)

No No No...you must be on the wrong TF list!!!! LOL
D Clark

I find my cats don't care whether the fuel is leaded or unleaded when they sleep on the 1/2 tonneau just in front of the gas cap.
Mark B.

Tom,
In addition to increasing octane, lead also acts as a lubricant to the valves, old technology engines relied upon the lead in the gasoline to coat and protect exhaust valves from the extreme heat of the exhaust. I've always noticed that the cars ran cooler & the valves were quieter when run on leaded.
Robert Dougherty

hello robert, i disgree. lead was not even added to gasoline until 1922,so old technology engines were developed and operated before tetra-ethyl lead was added to fuels. in the mid seventies, when lead was being removed, there was discussion about the effects of lead removal.there were several old car publications concerned enough about the removal of lead from gasoline that they conducted tests and found the effects of lead removal on valve seats to be negligible.they did discuss the known harmful effects of lead on our old engines, specifically, lead fouling of spark plugs, rings, valve stems and guides and exhaust systems. it is never too late for me to learn, so if you can refer me to any test results by any reputable automotive organization proving the harmful effects of lead removal on our old engines i would be very interested in reading it. it has been 25 yeas since the last road fuel with tetraethyl lead has been sold in this country. the cars are still running, the overhaul shops are not backed up with work....as far as your sticky valve problem, have you tried using a top oil??? thank you for your response. sincerely, tom
tm peterson

Tom,
Nothing more than my own experience. I don't believe their is any harmful effects to using unleaded...I have just found that my cars run better, quieter, and cooler with leaded gas.
Robert Dougherty

This thread was discussed between 08/11/2005 and 13/11/2005

MG TD TF 1500 index

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