The International Cessna^® 170 Association

Fitting the cowl I am finding the air filter frame is quite tight against the cowl opening. How much clearance do I need so I don't damage the cowl or air filter holder frame. I would expect the engine needs to have room to rock a little within the cowl. What do you think G

Yep, there is indeed a little clearance needed. There should be a rubber air-seal/weather-seal surrounding the opening to cushion against the air-box, otherwise the probable damage will occur to the AIRBOX. (another not-cheap item.)

I have a good 1/4 inch space all the way around but the 2 lower corners are in fact touching the cowl. I would expect with the rocking of normal engine operation this would hurt the air filter frame or air box. Any ideas how to free it up???????G

How old are your engine mounts and engine mount-to-airframe bushings? Lack of clearance on the bottom of the air cleaner usually means that your mounts need replacing.

Joe
4518C

sorry slow to get back to ya. My cousin is an ame and float plane guy and we put in solid bushing so I wouldn't expect any droop in the mounts tho as they say I have been wrong before. One joker here on the field suggested i enlarge the mounting holes on the airfilter frane so I could position it a little higher on the air box which I guess would work but I ain't crazy about butchering the hole Wadda ya think G

Lemme see, simatos.... Seems kinda like the Doctor noticeing your hand has a scratch on it and suggesting you simply cut off the hand.

I made a mistake according to my ex mechanic concerning this. After the paint job my filter box was touching in the lower left corner. BTW, Ole Gar and I observed that maybe 90% of the 170's on the Petit Jean Flight Line did not have that rubber seal around the box. I had already gotten a crack in that corner of my newly repaired cowling after just a few hrs (happens fast). Anyway to make a long story short, I pulled the Cowling off, took hold of the filter box and moved it in an up and over direction, then put the Cowling back on. Didn't feel like it really moved, but when I put the Cowling back on I found it fit good enough. Didn't take much to push it over 1/8 inch. I've already had a lecture from my mechanic.

You'd be surprised just how much movement is available to the cowls due/thru their mounting PK screws. If you install your cowl but don't tighten the PK screws until you have the cowl positioned just right...THEN tighten down the PK screws you'll have a better fit.
The engine moves somwhat when it starts. when it runs. and when it shuts down. (Not as much as a Leapin'-Lyc,...but it moves.) The airbox is also a somewhat fragile box, and it's not a cheap item to repair or replace either, so you'll not want to be shovin' it around, or having it touch against the cowl or it'll start cracking also. (Not to mention the stress relayed onto the carburetor and it's mounts.)

I will try the gentle adjustment of the cowl before final tightening of the screws and forego anything involving amputation, george did the washers show up by the way....Gary (Simatos)