open element filter..... again

[Old2New]

Guys, I know this has been asked a bazillion times all kver the internet but the serch function does not work on this website with my tablet so I can't use it. My question is, I have the choice between the original closed air filter element or an open element. One reason Its such a hard decision for me is that it seems to run a little better with the factory air cleaner than with the open element. Almost as if jt wants to run too lean with the open element. I know this is a carb issue, maybe jets too small, but without access to larger jets right now would it be better to use the stock air cleaner? And finally do you guys think it looks better to have the factory cleaner? I should mention that there are no vacuum leaks that would cause it to run too lean. If anyone would like to see pictures let me know.
The carbhretor is a 2100 with 1.23 venturies, 54f jets and sitting on top of a 390 fe. Everything is stock.

 

[40 Deluxe]

A number of factors enter in here. Does the factory unit have the hot air tube to the exhaust manifold? This is almost a necessity for smooth running during the cold damp weather you're having. What year is your vehicle? Car or pickup? As emissions rules came in during the mid-60's or so, fuel mixtures were set leaner so warm air to the carb helped vaporize fuel better. Unvaporized fuel doesn't burn so the result is in effect a lean mixture. Kinda self-defeating to add larger jets for this reason!
Some open element after market filters are worse than factory, either too small, too short, or poorly designed and mess up air flow into the carb. Some say air blowing from the fan can upset flow into the carb. If the air cleaner lid is too close to the carb bowl vents, fuel mixture can be affected.

 

[Old2New]

Oh shoot, I left out a bunch of details. 1968 galaxie 500, yes it has the heat riser from the manifold. It makes sence what your saying about it vaporizing the fuel better, and boy is it hard to keep running when cold... even with the choke properly adjusted.

 

[dmsfrr]

A number of factors enter in here. Does the factory unit have the hot air tube to the exhaust manifold? This is almost a necessity for smooth running during the cold damp weather you're having. What year is your vehicle? Car or pickup? As emissions rules came in during the mid-60's or so, fuel mixtures were set leaner so warm air to the carb helped vaporize fuel better. Unvaporized fuel doesn't burn so the result is in effect a lean mixture. Kinda self-defeating to add larger jets for this reason!
Some open element after market filters are worse than factory, either too small, too short, or poorly designed and mess up air flow into the carb. Some say air blowing from the fan can upset flow into the carb. If the air cleaner lid is too close to the carb bowl vents, fuel mixture can be affected.

Yes the design & shape of the air cleaner matters more than you might think.
Containing and keeping an efficient fuel / air flow thru the carb helps the engine run better.

Watch this 30sec youtube video.
Granted it's 2 two barrel carbs on a 4cyl engine, but you'll be surprised.
https://www.youtube.com/watch?v=zs8mnaouP8U

.

 

[Old2New]

Man that sounded really good when he let down the throttle. So would the stock air cleaner work like a velocity stack in a way by sucking air in faster through the snorkel? Is air flow slower through a big open air element?

 

[fordor41]

AS far as carbs go I have a 302 in my '41 Ford. Have tried 2100's with 1.02 - 1.23 venturies and 51 jets and really found no difference in how it runs. I have an open air cleaner and get about 18-19 MPG with 2:75 gears

 

[40 Deluxe]

Man that sounded really good when he let down the throttle. So would the stock air cleaner work like a velocity stack in a way by sucking air in faster through the snorkel? Is air flow slower through a big open air element?

Here's something to keep in mind when visualizing airflow: In reality, air is not "sucked" through the air cleaner nor "sucked" into the engine. It is pushed in by atmospheric pressure. A "fluid" (liquid or air or other gases) cannot be pulled into or through anything. Viewing it this way helps find and eliminate restrictions that reduce horsepower. Air is pushed from a high pressure area (the atmosphere around us) to a low pressure area (an engine's cylinder on the intake stroke). Air has mass so therefore has inertia and wants as straight a shot as possible into the cylinders. Sharp corners and bends set up turbulence which causes restriction even if the air cleaner seems big enough.

 

[Old2New]

Here's something to keep in mind when visualizing airflow: In reality, air is not "sucked" through the air cleaner nor "sucked" into the engine. It is pushed in by atmospheric pressure. A "fluid" (liquid or air or other gases) cannot be pulled into or through anything. Viewing it this way helps find and eliminate restrictions that reduce horsepower. Air is pushed from a high pressure area (the atmosphere around us) to a low pressure area (an engine's cylinder on the intake stroke). Air has mass so therefore has inertia and wants as straight a shot as possible into the cylinders. Sharp corners and bends set up turbulence which causes restriction even if the air cleaner seems big enough.

Ok thank you for that description. I alwayse visualized air being sucked into the engine.

 

[dmsfrr]

I like chrome and custom stuff as much as the next guy, and I suspect a factory air cleaner is almost out of the question in anything but an 'original' engine compartment, esp if the car is being shown almost anywhere.
The decision of what air cleaner looks good and works well is pretty much up to the owner.

However...
If you looked at the video I posted above, try to imagine what's happening under the hood when this car is going down the road. (photo below)
I believe a fair amount of his fuel is being lost into the wind. Certainly his mileage will suffer, and maybe the fuel/air ratio as well.

If the car works better for you with the stock air cleaner on, leave it that way and keep the chrome one handy for car shows.
.

 

[Daves55Sedan]

Have ya thought about maybe taking the original air filter can and stripping it, then take it to be chrome plated or something like that. If the car runs better with it but ya just wanna change the way it looks. Maybe paint the bottom can and take the top cover to be chromed?

 

[Old2New]

I guess what I am really trying to figure out is "WHY" it runs better with the stock air cleaner. Only thing I can think of is that the stock air cleaner is more restrictive and that the engine is running lean? I ordered bigger jets to see if it helps. going fron 54s to 60s. I know its a big jump but it can at least show me if it makes a difference.

 

[dmsfrr]

To see if the engine is running lean or rich the better way to tell is by the color on the center insulators of the spark plugs. They should be a light brown to grayish-tan.
Examples at this link...
http://www.vulcandrifterriders.com/sparkplugcolorchart.html

This may not be your favorite chart, and it's actually from a motorcycle website. It was just the first one I found with easy to see images. If you have a better one please share.

..... So would the stock air cleaner work like a velocity stack in a way by sucking air in faster through the snorkel? Is air flow slower through a big open air element?

Yes it's possible the overall shape of the oem air cleaner is creating a more efficient flow thru the carburetor than an after-market air cleaner.

.

 

[Old2New]

I wonder if the heat riser going from the exhaust manifolds to the element is helping as well? I put it back on yesterday and it drove better in every situation, hot and cold. So the obvious thing to do is leave it on! Its my daily driver right now so performance is more important than shiny stuff.

 

[Old2New]

Here is a good chart I found on google for rich/lean spark plug reading.

 

[40 Deluxe]

I wonder if the heat riser going from the exhaust manifolds to the element is helping as well? I put it back on yesterday and it drove better in every situation, hot and cold. So the obvious thing to do is leave it on! Its my daily driver right now so performance is more important than shiny stuff.

Yeah, Ford put that thing on there for a reason. The exhaust manifold gets hot almost immediately so the carb is getting warm air that vaporizes the fuel much better. It's especially helpful for vaporizing the wonderful ethanol that contaminates gasoline nowadays. Cold ethanol does NOT want to ignite! Some of it gets past the rings and dilutes the oil.
Don't worry about intake air getting too hot. There is either a thermostaticly controlled flap that will open when warmed up or a vacuum controlled flap operated by an EFE valve ("Early Fuel Evaporation").