can running lean cause pinging?

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What the specific car and problem? Typ wrong plugs(ext tip), dirty CC's and incorrect ignition advance are to blame if you are using the proper fuel. And if you have a Edlbrock AFB/AVS carb thats leaning out in transition from LTC to enrichment - get it professionally jetted (metering rods+) or replace it with a holley 735 or 780. May be a quick call to edlebrock tech could help.
 
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Got it! There's a guy over on the Lincoln forum that has the same carb and the same problem and fixed it by changing out the metering rods and springs. He's sending me the part numbers, then I'll change them and see what happens...

Thanks all!
 
Everyone says it does.

But your highest temps are at the correct [stoichiometric ratio].
Running richer or leaner has cooler combustion temps.

Guys running high boost turbos and very high performance engines use richer than normal mixtures to help cool things. This will reduce detonation, but simply because the massive fuel ingested is cooling things down. As long as there is a net power gain, they like it.

So I submit that lean mixtures burn cooler than normal.
And burn SLOWER, to boot!
Lean will NOT not burn valves or piston tops.
[Only if you have to run rich to cool things from other racer mods, lean can cause problems.]
[Only if you normally have to run rich to cool things down from other mods]
 
Hmmm.

My experiences have been that too lean causes EGT to soar and pistons to collapse or be damaged by detonation. Typically they run great right before meltdown. Maybe this is a case of needing to be artificialy rich to prevent damage.

Unless you are way too lean and power drops as well as temp.
 
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Running lean can make your engine EXLPODE!!!
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Air expands more than GAS!
 
Originally Posted By: mechtech2
Everyone says it does.

But your highest temps are at the correct [stoichiometric ratio].
Running richer or leaner has cooler combustion temps.

So I submit that lean mixtures burn cooler than normal.
And burn SLOWER, to boot!
Lean will NOT not burn valves or piston tops.


It is not so much the hot combustion temps, it is the temp of the piston crowns and chamber that matter. Running richer provides a boundary layer (mix of unburned fuel and air) on the combustion surfaces, a little insulation layer. The mixture on the combustuion surfaces never gets hot enough to actually burn. The layer lowers the overall amount of heat that makes it into the engine, but plays h*ll with hydrocarbon emissions.

Lean mixtures burn cooler than stoich.....yes, absolutely. Do lean mixtures push more heat into a combustion chamber/valves.....yes.

Lean does burn pistons and valves, but not directly. Lean conditions spike chamber temps, increased chamber temps cause detonation/pinging (near the intake valve head by the cylinder wall), the detonation blows away any boundary layer present in the chamber, more heat makes it into the combustion surfaces, and so on. It is a vicious cycle. That is why you see piston edges burned/melted and top rings siezed in the gap. Gets bad enough, you get a burned valve.
 
punisher - thanks for the detail. With that in mind I'll keep the leaner metering rods and springs and if I ever need to run a smog check on it I'll put the leaner ones in for the check.

Stay tuned, will replace the lean ones with richer ones this weekend...
 
Since you are talking about metering rods and springs I will assume that your dealing with an Edelbrock carb.

If so throw that piece of trash away and put a Holley on there. Trust me. Those Edelbrocks are junk, they resemble a Carter AFB but don't work as well as the AFB did.

I've got a Edelbrock carb with 12 hrs run time since new for sale cheap with no takers.After spending 8 hrs on a dyno trying to get it jetted correctly I swapped back to a Holley and picked up 90 ft lbs of tq and 60 hp at the wheels.
 
Metering rods and springs can be for a Quadrajet.
A complicated carb, but after much work they can meter well in all situations. Very versatile.
Modern FI is way better than any carb.
 
I think it would depend upon how lean you run the engine.
In a light plane, where you can adjust mixture as you operate the engine (you have to, to account for the loss of air mass with altitude), you can lean to peak EGT, but you can also lean the mixture enough that you run lean of peak EGT.
In short, you could have your engine run a lean enough mixture to cause elevated temperatures, but not lean enough to see lower temperatures.
Also, an excess of fuel does have a cooling effect.
 
I put the richer metering rods and different springs in my Edelbrock 1406 today - took it out for a test drive, the pinging is gone completely!

Thanks for all your inputs folks! This forum rocks!
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Originally Posted By: sasilverbullet
I put the richer metering rods and different springs in my Edelbrock 1406 today - took it out for a test drive, the pinging is gone completely!

Thanks for all your inputs folks! This forum rocks!
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+1, nice recommendation ARCO!
 
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