LA 318's

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Jul 8, 2009 | 10:18 PM

#11

Crazy4x4RT

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From: NM

Quote:

Originally Posted by soar_dude

Actually not! the biggest issue with early 70's and older engines running on unleaded was the heads. The metal used in the heads could not handle the abrasive action of the valves on the seats. the lead in the gas lubricated the valves and seats. I remeber friends of mine that had the old muscle cars trashing heads on unleaded gas. Then the oil companies have reformulated the gas to provide a chemical makeup that prevents valve recession in the older engines.

Lead was added to the gas in the 20's. It's sole purpose was to help with predetonation, caused by higher combustion engines. Not to lubricate valves. The lead eroded the seats, a side affect of the lead. Lead was stopped due to the health and environmental affects. Check this site to read it all! http://en.wikipedia.org/wiki/Gasoline

Now like stated before the lead helps predetonation. The higher rated octane fuels acts in the same exact way. So in order to keep a 1969 high compression engine in stock form to reach its full potential, you will need to use higher rated octane fuel and probably a lead substitute additive. I don't know what the numbers would be like if you didn't. But I'm sure somewhere of 5HP or so.

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