O-360 RV-8 K&N filter question

I purchased a flying RV-8 last year and am now preparing for the annual condition inspection. This aircraft has a Lycoming O-360 and the standard Vans airbox.

I want to purchase a second K&N air filter, but does this setup require cutting a notch and sealing the filter like on the O-320? I previously had an RV-6A with the O-320 that required a notched filter.

If the notch is required, what is the correct sealant to use?

Unfortunately this aircraft did not come with the builder plans and the drawings I purchased on a flash drive from Vans did not include the FAB plans.

Depends on the carburetor used. I think typically the answer is no, you dont need to cut the filter. But if the accelerator pump is in the way then you will need to cut it. The correct sealant to use is pro seal, the same sealant used in the fuel tanks.


Do not use RTV, it can break down from the fuel and get sucked into the intake.

No the filter does not get trimmed with the 360 carb.

Robin8er said:

Do not use RTV, it can break down from the fuel and get sucked into the intake.

Click to expand...

I thought Van's instructions are to use a high-temp RTV type sealant. That's what I have used without any trouble. I'd double check with them on it. That is a hot, greasy part of the airplane - I don't know if Proseal is appropriate in that kind of environment.

Permatex Ultra Black holds up just fine with no degradation from my 8 years of experience using it for that purpose of sealing the K&N around the carb pump protrusion. It sticks very well to the surfaces involved also.

No notching or sealant on the K&N for my O-360. There are tabs that it sits around but with time those filters shrink enough to no longer fit around tabs.
Good time to buy a new filter when that happens.

Thanks everyone. I?ve bought a new filter so I can replace the old if it has shrunk. I?m glad that I don?t have to notch and seal it.