What was the purpose of leaded gas hy don't we need it any longer??

[87LtdT]

Brother just purchased a '64 T-Bird (390 cu in) and is wondering what type of fuel to run. He had one back in the day and it needed premium or he got spark knock. Our discussion made me realize I really don't know why gasoline was leaded, nor why it doesn't need to be leaded now.

Oh...and what type of fuel he should run is an open question too

He lives near Milwaukee and typically has access to only re-reformulated gas. Don't know what re-reformulated is...don't sound good though.

Thanks, Bob

[1970gsx]

The lead lubricated the valves so they wouldn't wear out the valve seats. Cars now have hardened valve seats so the lead is no longer needed.

[BlownZ]

If the engine is anywhere near original then he will want to run lead additive in his gasoline.

[John Larkin]

Teach him the xylene trick Bob.

[ijames]

Adding tetraethyl lead (TEL) is the cheapest way to raise the octane of gasoline, especially gasoline that is created mostly by simply distilling crude oil. As part of reducing auto emissions, catalytic converters were required in the mid 70's and lead was banned because it poisons and deactivates the catalyst. To maximize the catalyst efficiency an oxygen sensor was also added a few years later, and the lead also poisons that. It turns out that the lead in the exhaust fumes was a major source of lead in young children, especially in inner cities, and lead poisoning causes mental development problems in young children so this was an unexpected health benefit that probably would have caused lead fuel to be banned anyway once researchers figured it all out.

To get the same octane without TEL requires a mix of further chemical processing steps beyond the initial distillation, and other additives, so gas costs more. Because carbureted engines without O2 sensors and computer controls from the 60's would run a little leaner and thus drop their hc and co emissions, in the 70's the epa decided that in the 80's gasoline would have oxygenated additives like ethanol and/or MTBE, and we would just live with the 20-30% drop in fuel economy. Yes, it is true that even with an O2 sensor and computer control the exhaust emissions do drop some, but how about that hidden 20-30% gas tax they just slid in? Oh, of course the auto makers were allowed to still use non-oxygenated gasoline when they did their epa fuel economy testing. I'm exaggerating a little because the oxygenated fuels are only required in epa non-attainment areas, but that includes most of the north east and California. When I got my car in 1990 I could get 24-25 mpg on the highway. Now, with Maryland gas (RFGII, reformulated gasoline II, third generation oxygenated low aromatic gas) I get 18-19 mpg on the highway, but when I get far enough south to get real gas I can still get 23-24 mpg. Sigh :-).

As for octane, the T-Bird should be just as happy on today's 93 octane as it was on premium back in '64, as far as knock and pinging. The lead also lubricates valves and valve seats, and a few engine families did have problems when unleaded came out, but I don't know if the Ford FE's were in that group or not, sorry. I have seen some little bottle of "fuel lead" for sale at auto parts stores, to lubricate the seats, but again, I don't know how well they work.

[87LtdT]

Thanks guys...looks like his best bet is to drive far enough away from MKE to get NOT reformulated gas and use 93 octane. If he is uncomfortable with the valve seat wear potential then a bottle of lead additive might be in order.

I found this from Chevron...which pretty much says no lead gas is fine with old cars cause they aren't driven much or very hard. Makes sense, but I'm always cynical of anything a gasoline company says .

http://www.chevron.com/prodserv/fuel...etin/unld-gas/

Question: will a mix of xylene or toluene be OK?? Any lead in either of them?? Downsides to using them in old engines??

Thanks guys...Bob

[TransAm WS6 420]

I've been told that the lead in the gas also has some detonation-reducing qualities, which is why todays race cars still run leaded 116. Any truth to this?

[DaveK]

Tetraethyl lead, Pb(CH2CH3)4, forms lead oxide, PbO, during combustion. This helps the gasoline burn more slowly which effectivly raises the octane rating. With a higher octane more compression (or boost) can be run without knocking.

-DaveK

1987 GN (factory ordered)

[TransAm WS6 420]

Originally posted by DaveK
Tetraethyl lead, Pb(CH2CH3)4, forms lead oxide, PbO, during combustion. This helps the gasoline burn more slowly which effectivly raises the octane rating. With a higher octane more compression (or boost) can be run without knocking.

-DaveK

1987 GN (factory ordered)

Awesome answer! Thanks dude!!!

[Buick From Hell]

Just tell him to add 1 ounce of Marvel Mystery Oil to the gas tank for every 15 gallons of gas he pumps in. That'll take care of any valve seat problems! (helps the guides too)

[87ttypeV8]

leaded gas also greatly reduced the cylinder temperatures while increasing octane

i would imagine maybe a mixture of some 116 octane leaded fuel with some normal pump gas would do the trick...
i have heard of the lead additives in autozone and what not... maybe this would help some?

[2quiktocare]

Lead in fuel was to help combustion and redue detonation. It causes the gas to ignite quicker and more completely. The problem was two fold though. Lead is known for causing brain damage in other problems in kids, and it also was a major problem with the Federally mandated catalytic convertors. Would burn up a cat in no time. Mark

[TurboBuickSix]

And just in case you don't already know, the seats could also be updated to the modern no lead style by your machinist.