Quote:
Originally Posted by gwowzer
Oh and I thought engine pinging was caused by pre-detonation of lower octane fuels.
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Quote:
Originally Posted by gwowzer
Usually running a higher octane will result in more of the fuel being combusted in the chamber which will prevent pinging.
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Pinging/pre-ignition is more likely at lower octane levels, but only if the engine compression and combustion environment is such that it may occur. If things are as they should be, lean or rich won't matter, it won't spark knock.
Gowzer, you're on the right track with that thought, but a few chemistry facts incorrect.
A higher octane fuel does not result in more of the fuel being burned, preventing pre-ignition.
Higher octane fuel actually has less BTU of energy and less actual gasoline in it per unit measured. The octane (which is not commonly known that octane isn't only a rating, it's an actual chemical- C8H18), does not by itself burn easily at all. So when octane (the chemical) is added to gasoline, it reduces the combustibility of the fuel as well.
So it isn't that more fuel is being burned in higher octane content fuels, it's that there is less fuel present and that the octane added makes the two combined chemicals (gasoline and octane) less likely to ignite under compression than the gasoline alone.
Now because octane is a carbon heavy chemical, if it can't be burned by high compression and hot flame fronts from the spark event, it can lead to large carbon deposits and build up in "normal" engines.
But again, none of this octane/ethanol-free blah blah blah talk has anything to do with being rich or lean.
OP, either open up the stock carb and pop a new, larger main jet in there, or buy a $25 HWBNDE branded vm26 from Amazon and a $!0 jet kit and plop that bad boy on there; tune for the best sized main jet (on an otherwise stock engine at your elevation, I bet a 110 or 115 would be good).