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didget69
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Location: Capital, North Carolina
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 Posted: Sun Mar 25, 2012 9:56 am Post subject: Myth of lead in gasoline required for older engines |
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Many people erroneously continue to spew misinformation about the need for Lead in gasoline. I see this question/comment come up from time to time regarding older engines 'requiring' tetraethyl Lead or Lead substitutes in order to run 'properly'... This tale was shot down 12 years ago in an excellent article by Jamie Kittman - the entire issue of putting Lead, specifically TEL, in gasoline was purely for profit motives. Other additives could have been used to reduce spark knock & would have been safer to use. Changes in valve seat materials resolved the need for Lead additives.
http://www4.hmc.edu:8001/Chemistry/Pb/resources/secret%20history%20of%20lead.pdf
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lostinbaja
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Joined: December 19, 2004
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Location: Frankfort, Illinois
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| Posted: Sun Mar 25, 2012 7:19 pm Post subject: |
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So what you are telling me is my 1953 Chevy, 71 International, 77 Landcruiser and 65 VW have the updated valve seats that require no lead?
Jamie Kittman's credentials tell me, he cannot prove what he has quoted in his article. He is a Lawyer, Rock Band Manager and part time Auto Journalist. He is not a Chemist or an Engineer.
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BL3Manx
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| Posted: Sun Mar 25, 2012 9:00 pm Post subject: |
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| Some low performance recip aircraft engines have supplemental type certificates(STCs) which permit them to use unleaded auto gas. However, the only fuel widely sold in the US for use in reciprocating aircraft engines is 100LL AvGas. LL stands for low lead. Avgas with lead is the only fuel that has both the octane and the low vapour pressure which enables a high performance recip aircraft to remain airborne for a predictable period of time. |
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forkzilla
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Location: North Central Ohio
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| Posted: Mon Mar 26, 2012 3:28 am Post subject: |
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| It looks as if 100LL may be gone soon also. I have run unleaded 87 mogas in my plane for 27 years and have never had any problems due to fuel. |
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rmckay
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Joined: April 27, 2011
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Location: Fairfax, Virginia
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| Posted: Sun Apr 08, 2012 10:08 am Post subject: |
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This thread just kind of dropped off without really answering the question about the need for using a lead substitute in older engines.
I'm no mechanic, so any info would be appreciated.
I have a 1968 1500cc engine with stock heads, so it doesn't have the harden valves/valve guides meant for dealing with unleaded gas. Should I be using a lead substitute?
Another question I have is about using ethanol blended gas, which is all that is available here. What affect does that have on a 40+ year old engine?
Thanks, all.
Rick
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didget69
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| Posted: Sun Apr 08, 2012 11:00 am Post subject: |
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| rmckay wrote: |
I have a 1968 1500cc engine with stock heads, so it doesn't have the harden valves/valve guides meant for dealing with unleaded gas. Should I be using a lead substitute?
Rick |
Rick, I'd ask Jerry about his expert opinion on what you need to run in your car.
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Letterman7
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Location: Downingtown, PA
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| Posted: Sun Apr 08, 2012 11:04 am Post subject: |
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I'm no expert by any means either, but from what I've read on the engine forum here, running a lead additive is recommended for stock engines. I don't know what it does, exactly, to aid in valve seat life. Ethanol is known to rot the rubber hoses and internals of carburetors. Keep an eye on everything if you don't run it every day.
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didget69
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| Posted: Sun Apr 08, 2012 11:15 am Post subject: |
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MY point is that lead was not required to decrease knock. Did the addition of TEL work in reducing knock? Absolutely. But there were other substances, like alcohol, that could have been used. But no one needs a patent on alcohol, whereas Ethyl could be patented & profits derived from it, at the expense of the environment & detriment to one's health...
I haven't researched the alloying of metals content of the heads of a 1953 Chevy, 71 International, 77 Landcruiser, or 65 VW, so I can't say that unleaded fuel is more/less damaging to those engines. Differing metals will be affected in different ways based on the fuel used.
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BL3Manx
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| Posted: Sun Apr 08, 2012 9:56 pm Post subject: |
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| rmckay wrote: |
| I have a 1968 1500cc engine with stock heads, so it doesn't have the harden valves/valve guides meant for dealing with unleaded gas. Should I be using a lead substitute? |
Its the valve seats which are hardened steel, not the guide. Valve guides are often made of bronze alloy and valves are often made of stainless, neither of which are very hard.
The engines which have problems with unleaded gas are the very old ones that have valve seats made of the cast iron parent metal of the block or head. Standard VWs have mild steel seat inserts, which are strong enough to survive without any lead additive.
Last edited by BL3Manx on Sun Apr 08, 2012 11:04 pm; edited 1 time in total |
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BL3Manx
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| Posted: Sun Apr 08, 2012 10:00 pm Post subject: |
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| didget69 wrote: |
| MY point is that lead was not required to decrease knock. Did the addition of TEL work in reducing knock? Absolutely. But there were other substances, like alcohol, that could have been used. But no one needs a patent on alcohol, whereas Ethyl could be patented & profits derived from it, at the expense of the environment & detriment to one's health... |
Yes lead is toxic but saying the only reason it was sold was for higher profits just isn't so. Lead was also cheaper(remember 32 cent 104 octane premium) and better at raising octane and better at protecting valves from wear. Also, alcohol absorbs water from the air and leads to corrosion and contamination of fuel systems via bacterial growth. Lead is toxic to bacteria. Bacterial growth in fuel tanks (and flameouts) aren't trivial problems.
The higher octane Avgas (up to 150) the Allies had (via TEL) was what enabled the RR Merlin and P&W R2800 engines to operate the way they did and giving air superiority was a small but important help in winning the war. When the war ended the advanced fuel technology just carried over.
Yes, Americans have lower blood lead levels now than they did 20 years ago, but how much of that is due to removing lead from gas and how much from removing lead from paint, plumbing, the solder in tin cans, and even toothpaste tubes? |
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