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Discussion Starter #1
Is it normal to have to re-adjust your idle mixtures year to year? Started driving the ZZ383 with a Holey 770 Street Avenger, ran it last year and had everything pretty well in tune. Well I noticed the idle RPM bouncing around wildly, couldn't be my ignition or timing, it's computer controlled. Took a look at the mixtures and they were off. Idles smooth as silk again. What the heck can cause them get out of whack like that? Used the same gas I've always used, at least fromthe same station 92 octane.

I'm really thinking electronic fuel injection to get rid of all these headaches. Plus more tunability. At least easier with a laptop and better mileage.
 

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Welcome to the world of "Seasonal" fuel. :yes:

If you tune it on the edge you'll be going through this 2 or 3 times a year depending on where "Home" is. Reason being the fuel companies have figured out that the fuel we use needs to have different evaporative points (drop points, boiling points, etc..) for different climactic conditions------so the fuel will evaporate like it's supposed to and not in the fuel lines, carb or gas tank..

Most people just set their idle mixture a little fat (either knowingly or unknowingly) and avoid 90% of the problems.:yes: Hence: "Mine never change"...:rolleyes:
 

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dirt in the air bleeds? clean them up with carb cleaner or cover the choke horn with your palm and accelerate to forcefully clean it out:D
 

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Welcome to the world of "Seasonal" fuel. :yes:

If you tune it on the edge you'll be going through this 2 or 3 times a year depending on where "Home" is. Reason being the fuel companies have figured out that the fuel we use needs to have different evaporative points (drop points, boiling points, etc..) for different climactic conditions------so the fuel will evaporate like it's supposed to and not in the fuel lines, carb or gas tank..

Most people just set their idle mixture a little fat (either knowingly or unknowingly) and avoid 90% of the problems.:yes: Hence: "Mine never change"...:rolleyes:
Actually, it is the government that makes the gasoline refiners change the formulation for the different seasons. Supposed to be an anti-pollution thing. There are somthing like 50-60 different formulations for the different seasons and geographic locations.
 

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Discussion Starter #5
Well certainly what I'm using now can't be the same as what I was using at the end of the summer last year. It took some fair messing about to get them dialed in again. I imagine it will change again. Nothing should be dirty, there's less than 5000 miles on the new Holley.

When it's tuned it runs super like fuel injected so you can really tell when something starts to go away.
 

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Weather is your biggest change.

Also engine wear and carbon build up, fuel residue in carb all play a part.

The engine does not have a PCU to change every milla second to conditions.

Al
 
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