----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----At 02:59 PM 12/20/2005, David Douglas Winters wrote:
The previous owner of my ‘coupe advised me to run it on half automobile high-octane and half 100LL to avoid deposits.
Any opinions on this practice?
David:
It may be advantageous to run a little lead through the engine when the valves are new or recently overhauled. It may even be advantageous to run a little lead through periodically, but 50% 100LL all the time is a lot more than you ever need. A mix of 1 part 100LL to 4 parts unleaded fuel nets out at the maximum limit for 80 octane avgas. I personally see no reason to use any leaded fuel after break-in. The 73 octane fuel the engine was certified on was essentially "regular" (as opposed to "ethyl") and was lead free.
Use of higher octane fuels is also without advantage. Any high quality alcohol free auto gas rated 87 octane is sufficient.
If one chooses to use 100LL the lead can be controlled by using an additive called TCP which aids in scavenging the lead from the combustion chambers.
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