Fine tuning mixture via air filter?

[Some Car Guy]

Anybody find a difference in their mixture by changing air filters?

Last fall I noticed my car ran much much better when the weather cooled down. like it was rich and the denser air brought it in line when the season changed. The plugs had looked an ok tan and the metering rods in the avs were only slightly richer than oem on the power step so I thought it all was ok until then. It’s an all stock 440. Numbers carb, Etc.

so I hunted down some other rods over the past year and this fall I tried a leaner set on the cruise and power step and I think the engine likes the change. Trouble is rods are hard to come by and you have to wait for the right set(s) to appear. Could find an even leaner set this week or not at all.

occurred to me that trying a k&n type filter might get me a tad more lean. Engine Masters did a show on how several brands/types did as far as power, but they didn’t rejet the carb for each. Just dynoed each, finding very little power between any setup.

A magazine mentioned a couple years ago that the avs is pig rich from factory to account for all elevations. I’ve seen people say modern fuel burns differently than the old stuff and the oxgenation makes plugs look leaner than they really actually are. Don’t know if that’s true or not about the fuel, just hearsay.

I don’t have a wide band, don’t have a dyno to go test on, and won’t be going efi. This is just me fine tuning and comparing how it does each time out.

 

[PurpleBeeper]

As I understand it, in general, denser air = more power. You could be right about it being closer to perfect air/fuel mixture in cooler air though. With no technology to work with, I think you're down to reading your plugs and setting idle mixture by "maximum rpm at idle". I'm not sure about the fuel burn difference

 

[Some Car Guy]

I set the idle mix by vacuum gauge.

 

[R413]

Whatever magazine that said an AVS was pig rich from the factory is very confused.

How modified is the engine, how big is the camshaft in your car?

if your tund is right on the edge then a little change will make it run different, better or worse.

 

[Some Car Guy]

Whatever magazine that said an AVS was pig rich from the factory is very confused.

How modified is the engine, how big is the camshaft in your car?

if your tund is right on the edge then a little change will make it run different, better or worse.

I dunno about that. Eberg has been around a long long time and I’ve yet to catch him up on his tech. As I said, it’s a stock 440 down to the correct carb. 69 HP. Does have electronic ignition.

 

[lewtot184]

The factory avs is far from being calibrated rich in factory tune. The edelbrock 800avs is a different story in my experience. Maybe ehberg confused the two?

 

[RemCharger]

Just another wonderful gift of the edelbrock carb.
No idea wtf is going on with the fuel level in the bowls unless you Crack the carb into 2 pieces.
Even then it's a "hope+pray".

 

[Cranky]

I know for a fact that my engines produce lower NoX with the air filter out of the canister.....and that's how I got my 95 Dakota to pass emissions testing when it was required. Cooler air is dense and it lowers combustion temp a bit and having non restricted air inlet helps in making horsepower. Cold air into a hot engine always makes more power and less NoX but who cares about NoX lol

 

[Some Car Guy]

The factory avs is far from being calibrated rich in factory tune. The edelbrock 800avs is a different story in my experience. Maybe ehberg confused the two?

He was specific about the avs, saying since the cars went all over they were safer going out rich than lean. The avs has some emissions deal that adds air sometimes. That would be different than what the rods and jets do. I plugged the hold to the idle air bleed thing and it ran better from a stop.