Engine Baffling - Not "Baffling" At All

Part 1 - the seals

What we're talking about here is the soft parts that keep air in the "Plenum" on top of the engine of the Ercoupe. This kind of baffle seal is common on just about every horizontally opposed engine installation.
First, a quick look at what I was replacing. Seals, like some holiday guests, over stay their welcome. Mine were stiff and let air out around the edges. Here is what I removed:

This piece went around the top of the baffle (metal part) at the back of the plenum. It had been in who knows how long!

The procedure is to remove the fasteners. In my case, there were a bunch of small machine screws with nuts on the back. I simply unscrewed all and replaced with new. I used solid metal nuts; the "Nylok" ones are not supposed to be used inside the engine compartment - heat causes failure.

I used new baffle seal material; check with "the usual suppliers." This is a "Cut it to fit" operation. One may use the old baffle material as a guide, but be sure it is cut "generously," so there is material to lap around the cowls. My original installation was with machine screws and nuts. I used this method for reinstallation.
You can order it from Aircraft Spruce It comes in different colors: orange, blue and black. I chose the latter, to fit the colors of the baffles.
The seals should flatten out towards the inside of the plenum to help seal the air in. The idea here is to force the air to go through the cylinders and not escape.

After seal material has been installed, check cowl for fit. One may need to trim a bit, but do not get it too short!

The above shows the cowl ring put on.

Above is a shot of the right side. Note that the metal upper right cowl support longitudinal piece goes through the baffling. The cowl attaches to this assembly so that the air can't escape.

The above shows the final installation. The cowl is not on but the nose bowl is in place.

This is a shot with the cowl on.

Percy G. Wood; 2013