The Cessna 120-140 Association Forum

Time to get prepped for winter flying . These are similar to the original ones found in the parts catalog. I zip tie the front on and I've noticed I loose some of the forced air that goes to my heater tube so I opened a hole there? The oval ones have a wing inspection retainer (flat spring metal on back of the round cover) cut down to size and two rivets. Oil temp blast tube is a metal push cap with some tape over it for safe keeping. I also cover my air inlet tubes at the leading edge with a cover plate and use the existing screws to hold it on . Have skis but never had them on too much work at our plowed runway. Stay warm and safe. Go have fun

Those look really professional.

My covers are aluminum tape from the aviation aisle at HD. Matches my aluminum skin and no danger of scratching.

The question I have is how do you decide how much inlet to cover?? I don't have CHT and don't want to cook the heads trying to get the oil temp up. At 30F I struggle to get 140 OT with sump blanket, no blast tube, case vents covered, cover on oil filter, 1/2 inlet taped over.

The factory covers are 3" wide (to the best of my knowledge), and the rule of thumb is you can cover the cylinders, but avoid covering the heads.

I think my heater inlet is outboard, but can't see it from here.

Agree with John C and the original covers had a decal that said " remove above 70 degrees " seams a little hot for covers at 70? and with head temp at 20-30 degrees rushing over them I've been told you'll never hurt the small Continentals? Our engine runs cool on a 80 degree day and its never past 180 on oil temp.

Thanks, Without having the plane to look at I would say 3" is roughly 1/2---so don't cover more than half. I tape from the bottom up using the grill fins to support the tape. I believe some of the later 140 or 150s had a baffle that came up about 1/2way in front of the front left cylinder. Otherwise it looks to me like it is so close to the cowling (1 inch??) on my 1946 model that to some degree the head blocks air from getting into the top region and to the back cylinder. Especially if I left only that area in front of head open.

The 150 baffle in front of the cylinder is intended to channel air tightly around the cylinder heads, not to block flow into the cowl. Since the 140 does not have that baffle I feel it would be safer to block the inner halves of the cowl inlets rather than the bottom halves, but it may not matter in the end. The goal is to avoid any hot spots, especially on the aluminum heads.

The oil tank cover and the blast tube cover are placarded for removal above 70 degrees F. The cowl grill covers are placarded for removal above 40 degrees F. I think the small plugs below the prop are also, but I don't have any documentation to that effect. Mine had decals on them, but that was 30 years ago...

Hi Jeff...do you wrap the fins with electrical tape or something to keep the zip ties from scratching the paint? I plan on making some covers like yours.
Josh

Before I knew what a proper air block was for the grills I cobbled these together in a few minutes and they've worked great over the years. Adjustable, and they are on the inside of the grill so if on a long shot they came un-hitched at least they wouldn't nail the prop. Scrap aluminum and a few u-bolts, leading edge tape to protect the grill paint. 0-200 engine, baffles apparently ala' 150.

6597 wrote: ↑Fri Dec 23, 2022 10:56 amthey are on the inside of the grill so if on a long shot they came un-hitched at least they wouldn't nail the prop.

That's how the factory parts work, except they're spring loaded "U" clips instead of bolts.

I have historically taped off the inner half of the right side and the outer half of the left side (to keep carb heat and heater snorkels open) with no ill effects in both a 170 and a 120. I made plates for the 120 but haven’t used them as it’s easier to use blue painter’s tape when needed. On the 120 I think “winterization” starts at 60 F, which sort of makes sense if you follow the oil temp is OAT + 100 F.