Im running one of the flat cobra style air filters for my 289 and have been for almost 3 years. Its always seemed like my engine was a bit hesitant. Today after adjusting my carb I decided to take the car for a drive with out putting the air filter back on. Wow! What a difference. My car was so much more responsive with zero hesitation.

After I got back, thinking it was just a carb adjustment issue, I plopped back on the filter and took off for a short drive. The sputtering came back along with the lack of performance.

Just to verify my theory here, the filter came off one more time and the car was solid once again. Any ideas on whats going on?

Any help or ideas would be great!

 

I'm assuming when you say flat cobra style air filter you mean the oval one? The other thing is to make sure the filter element is like 2.5-3"s high because if it too thin it will reduce airflow.

 

Yes its the oval and I use the standard filter that came with it that's about 3in tall. Im wondering if a k&n would help fix the issue

 

Make sure the filter lid isn't too close to the vent tube on the carb. If you're restricting air flow to the vent tube then it will cause fuel delivery issues.

Measure it up and verify, or switch to a regular round aircleaner. Most of them have a raised center section to give more clearance.

Also, if I remember right those oval air cleaners don't have a very smooth transition into the carb. The drop base ones I use on my racecar (& on my mustang) have a much smoother transition. They're cheap @ most of the race car suppliers websites.

 

the filter should be 'big' enough. I run the same with a strongish 302 and no problems. no different to round cleaner. so either the filter is full of firt or the lid is too close to the carb

 

All filters are not created equal. A K&N will flow better at the expense of letting a little more dirt into the engine (I have heard this about K&N filters, no I have NOT run my own test).

But in any case, the filter that came with the air cleaner might not flow worth a damn. I would probably just run a K&N since I don't live in the desert anymore.

 

the car does not get driven too much, maybe 1-2X a month at the most so I dont think the filter is clogged up. I will check out the lid. I am using the plastic spacer that came with the filter so there is some space.


EDIT UPDATE.

Well the lids not blocking anything.


While I was at it i measured the original filter in there and its only 1.74in. When I pulled the old filter out it stunk like gas and was a bit on the heavy side. I have a feeling the filter is clogged up with gas and grime. Amazing since the car is almost never driven!

I do plan on getting the K&N for more air flow since it cant hurt. The new filter is slightly bigger at 1.813in and ill never have to worry about getting a new one again. I will let you guys know how it goes. Sounds like a clogged filter was the problem.

 

actually i just thougt of it now. The oval aircleaner is different to the circlular ones in that the base that sits on the carb is a cylinder, while the circular ones usually go straight sideways (don't have a cylinder at base). you are not interfering with you choke linkage by any chance?
with demon carbs thats a known problem

 

What brand is the air filter? If its some cheapo brand, it may not flow well.

Just buy a good Wix or similar filter. I run a Wix on a round air cleaner, and it works great.

I used to have KN on all our vehicles. I probably will not ever run them again. They did nothing that I could see to help any of our cars/trucks. They did not really run any better or get better fuel economy. We had them in F150s, Mustangs, Honda, S10, Dodge Caravan, Nissan Maxima etc.

I had issues with replacement filters and their supposed performance intake kits for newer EFI vehicles. There were areas in the filter media that I could see through. How does that filter at all?

I also don't like them, because they are a hassle to clean and re-oil.

http://www.nicoclub.com/archives/kn-vs-oem-filter.html

http://www.bobistheoilguy.com/air-filtration-test/

http://www.bobistheoilguy.com/air-fi...ltration-test/

 

blah.......well my problem was not the air filter.

It happened to the filter shroud was touching the top of my distributor cap causing it to arch, taking away power to the car. This explains the hesitation that I thought was suffocation.