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simple_stan

leaded fuel

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simple_stan

These older engine were built when the only fuel was leaded. Do they have hardened valve seats? My 8N was built with hardened seats, so it wasn't new technology. Sould I add a leaded supplement to the fuel?

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BLT

Well for one thing you don't have any build up on the valve. There was an article years ago by Briggs that they like no-lead for that reason. Never read anything on pinging with low compression engines.

Every so often my 89 Merc would ping on slow speeds in OD.

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TimJr

Everyone should care if their engine pings! Pinging is an errant flame front in the combustion chamber. Prolonged pinging or it's even worse version - outright detonation - can/will lead to damage to spark plugs, pistons, rings and performance.

Briggs doesn't care about octane because the old flat head engines only have about 6.5:1 compression, and are able to safely run on about 77 octane. Typical pump gas is 86 octane at the lowest in America.

An OHV Briggs is somewhere between 7 and 7.5:1 I believe. They usually need the 87 octane - I don't think they are rated to run on as low of octane as an old flat head.

However, a modified flat head - one with changes to increase compression or advance timing - that ups the need for octane in a hurry. Been there, done that, lucky I didn't break a piston... Tim

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fishnwiz

I must be missing something or have lead a sheltered life as I have never heard nor do I know what a samll engine sounds like when it pings, and I have run hundreds of small engines?...Just me I guess!

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MrSteele

I must be missing something too. I run unleaded, of course, but always run the 93 octane, have been for years, around 40 of them. I have never had a problem with anything that is inside the engine, except that the innards are always clean. Even the oil remains like new, even without a filter. I have a ZZ Briggs on a garden tractor that gets well used all gardening season, the 65 Landlord with a 10 HP cast iron, and am working on a sister to the ZZ, only she'll be a few years younger than her older brother. I don't work on my engines, usually full choke, pull the rope a couple of times til gas runs out of the carb (on the ZZ), half choke and he is up and running. I start it rich, adjust to whatever I am doing, whether plowing or cultivating. The Landlord is a simple full choke til the engine turns over a couple of times, and we are off to the field. I am a firm believer in high octane for all...ALL small engines, including a 1 3/4 HP Hercules I have been showing for years, chai9nsaws, weed whackers, blowers, etc.

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