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Looking for the right air filter ; Marvel 4

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Greasykdstf

Member
I bought an RV9 already built and am looking for the right air filter. It has a modified K&N filter with RTV added to allow for room for the filter to seat because of protruding accelerator pump bowl. Just spoke with someone who had a similar setup and ingested the RTV causing engine failure and forced landing. I would prefer to find a filter that simply fits without being modified. Does Vans recommend or does anyone know of a good replacement for a modified K&N? This is being fitted on an O-320 with Marvel M4-SPA carburetor.

I’m aware that many aircraft fly well without air filters but would like to explore all options.

Thanks

Joe
 
I believe the instructions call for fuel tank sealant to be used to seal that area, not RTV… the O-320 carbs have that nub that needs the air filter notched out.. that’s just the way it is.
 
I used plastic food wrap (Saran wrap) on the carburetor to keep the fuel tank sealant from sticking to the carb. I applied a gob of fuel tank sealant (Proseal) on the filter in the carved out area and mashed it onto the carb. secured with the lower plate and bolts. Let it setup for a day then remove the plastic wrap. The filter molded nicely to the carb. You can carve off excess after it is setup if you need to.
 
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Air filter..........

Zero4Zulu said:
I used plastic food wrap (Saran wrap) on the carburetor to keep the fuel tank sealant from sticking to the carb. I applied a gob of fuel tank sealant on the filter in the carved out area and mashed it onto the carb. secured with the lower plate and bolts. Let it setup for a day then remove the plastic wrap. The filter molded nicely to the carb. You can carve off excess after it is setup if you need to.
Click to expand...

I remember someone had a setup that had a filter that did not need to be notched. I tried to search it but couldn't find it....it was fairly recently....
 
Thanks for the Tip and the link

This is great. Thanks for the link to the photos. I will be performing this modification.
 
3322 Filter

BMW_X6M said:
This is great. Thanks for the link to the photos. I will be performing this modification.
Click to expand...

You bet! I have the filter but have not tried the modification myself. I don't anticipate any problems. If it happens soon (it's on The List!!), I can forward photographs. Filter is available locally or online. O'Riley auto parts had one....:) Get the recharge kit while you are getting things if you don't have one already..... It has a cleaner and the new RED oil to turn it near-new again....
 
Greasykdstf said:
I bought an RV9 already built and am looking for the right air filter. It has a modified K&N filter with RTV added to allow for room for the filter to seat because of protruding accelerator pump bowl. Just spoke with someone who had a similar setup and ingested the RTV causing engine failure and forced landing. I would prefer to find a filter that simply fits without being modified. Does Vans recommend or does anyone know of a good replacement for a modified K&N? This is being fitted on an O-320 with Marvel M4-SPA carburetor.

I’m aware that many aircraft fly well without air filters but would like to explore all options.

Thanks

Joe
Click to expand...

The mentioned E-3322 will fit the O320 (I use this filter) without modification. You need to shape it around the bump and that's it.
I run it for 5 years and toss it. I did find a paper replacement that will filter much better, and will do a test next replacement. K&N's are for performance first, and filtering is second on the list.
KN.JPG
 
Air filters

gasman said:
The mentioned E-3322 will fit the O320 (I use this filter) without modification. You need to shape it around the bump and that's it.
I run it for 5 years and toss it. I did find a paper replacement that will filter much better, and will do a test next replacement. K&N's are for performance first, and filtering is second on the list.
View attachment 40876
Click to expand...

Excellent! Let us know what you find. I would be interested to know if you notice any performance changes. I kind of like the "performance first" philosophy. We mostly fly in pretty clean air. It's when we have to land, reluctantly, we need filtering first!

Someone posted in a previous discussion that he hated the 3322 but I don't recall why......

Do you have a part number for the paper filter?
 
Roadjunkie1 said:
Excellent! Let us know what you find. I would be interested to know if you notice any performance changes. I kind of like the "performance first" philosophy. We mostly fly in pretty clean air. It's when we have to land, reluctantly, we need filtering first!

Someone posted in a previous discussion that he hated the 3322 but I don't recall why......

Do you have a part number for the paper filter?
Click to expand...

The 3322 is thinner and what allows you to form it. It only works on an O320.

After I prove the paper filter, I will post the part number.... I will say it is made by the Leading MFG of filters and has a Fairley common application. Let's see if it will fit first.

I just hate the cleaning process of the K&N filter... plus the shrinking does not make it lifetime. It also had the lowest score in filtration.

Paper filter, look in the snout, if it's dirty, toss it.

Here is just one article on filters..... https://www.nicoclub.com/archives/kn-vs-oem-filter.html

K&N used on modern cars have also spoiled some mass flow sensor and caused the owners a lot of unnecessary grief.
 
This is great news. I am not comfortable with cutting a notch in the filter and then making it fit with a glob of rtv or pro seal. Will try the E-3322 next time I have the cowl off. Please keep us posted on the results of the paper filter.
 
Dystevens said:
This is great news. I am not comfortable with cutting a notch in the filter and then making it fit with a glob of rtv or pro seal. Will try the E-3322 next time I have the cowl off. Please keep us posted on the results of the paper filter.
Click to expand...
Did you ever go with the 3322? I’m due for an oil change and filter change. Mine is shrunk and want to not have to cut a notch if I can avoid it
 
An alternative that I have on my O-320 RV-6 is an aluminum spacer, about 9/16 thick, that puts the Fab and filter below the acceleratpr pump well.
So. no need to notch the air filter.
 
Trooper11040 said:
Do you have any photos of your 0320 FAB setup?
Click to expand...
Here's a picture of the spacer that I made that drops the FAB down a little over an inch. I did it so that my FAB would line up with my cowl inlet better. A side effect was that the filter also clears the bump.
 

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