Matt's RV-7 Project

More progress on the baffles… CB-706B spacer, check:

Riveted the CB-1007B bracket to the aft right case baffle. These rivets were kind of a pain to set.

Deburred this bracket and attached it to the front of the engine, using one of the existing case bolts and a new lockwasher:

There's another bracket that's supposed to mount to the back of the engine, using the two aftmost bolts. Uh, sounds great, but my engine has a bunch of stuff there already.

I knew I was going to have to move the ignition coils anyway, since the location where Mattituck installs them won't fit when the rear baffle is installed. But even after removing the coils, the fuel line is in the way.

Much better… I gently reshaped the stainless steel fuel line with my fingers until I had about 3/16" clearance from the bracket, then reoriented the adel clamp and its supporting bracket to secure the fuel line in its new orientation. I still need to find a new home for the ignition coils, but that will come later.

Time to start fitting the baffles to the engine. If you think this will be another long, drawn out exercise involving a lot of repeated installing, removing, and trimming, you are correct! I spent half the day just getting these three pieces to fit somewhat well:

As delivered from the factory, the orange silicone gaskets under the rocker covers interfere with the fit of the baffles:

I thought I'd have to trim the gaskets all around, but the only cutting I had to do was in removing the little half-circle tab of rubber at the top. The rest of the fit adjustment was done by loosening the rocker cover screws and shifting the gasket around to make it fit the shape of the baffles.

This area had some interference with the manifold pressure hose:

After grinding a relief notch, the baffle can lay down against the #3 cylinder.

I didn't like the un-reinforced screw hole in the previous photo, so I made a little doubler out of scrap and riveted it on.

An entire day of work and all I have to show for it is baffling for one side of the engine. And I still don't know where I'm going to mount the ignition coils, oil cooler, or any number of other things. Oh well, I guess I must like solving problems or I wouldn't be doing this…

Time to start on the engine baffles, which form a box on top of the engine to direct cooling air down through the cylinder fins. Everything I've ever read about the baffle kit has mentioned weak instructions and poorly fitting parts. However, Van's must have re-engineered the baffle kit sometime recently, as my baffle parts are CNC-punched and the instructions feature computer drawings. They are still confusing and contradictory, but at least the pictures are pretty!

Lots of sheet metal parts:

You start by chopping some partially pre-cut angle stock into six or seven separate pieces, which will become brackets and stiffeners:

Various pieces have stiffeners and doublers attached. I riveted on the bolt-hole doublers as instructed, but I am holding off on riveting anything else until I have a better handle on what's going to fit and what will need modification.

It didn't take long to get crosswise with the plans… on the second page, they want you to start cutting and drilling the port-side aft baffle for mounting the oil cooler. However, at this point you don't know how tall the baffles are going to be, which means you also don't know where the oil cooler should be positioned vertically. Not to mention, I'm not sure I'm even going to be able to put the oil cooler on the baffles anyway (see below).

I decided to leave the oil cooler stuff along and skip ahead in the baffle plans. In this area at the right-side aft corner, the preformed parts don't quite match up:

Rather than force the parts together – a recipe for cracking – I made a little 0.032" spacer to fill the gap:

Many hours later, I now have most of the bolt-hole doublers riveted to the baffles, and about half the baffle pieces deburred. Smoothing the edges of all those funny-shaped parts is highly tedious.

This is my oil cooler… it's a Stewart Warner 8432R, which is a bigger version of the 8406R, which is itself a higher-quality replacement for the no-name cooler that Van's will sell you. I let the guy from Pacific Oil Cooler talk me into buying this one – the argument being that it's easier to fix an installation with too much cooling capacity than too little. That does make sense, but if I'd known how little room I'd have to mount it, I might have gone with the next size down!

The oil cooler is beautifully made – look at those welds! – but it's also heavy and expensive and kind of fragile. I didn't want to risk dropping or damaging it while experimenting with mounting locations, so I built a dimensionally accurate stand-in out of scrap wood. If the wooden oil cooler fits, the real one will too.

The plans want you to put the oil cooler here, on the baffle behind the #4 cylinder. I might be able to make that work, although the flimsy sheet metal baffles will have to be strengthened considerably to properly support this brick.

Another possible idea is to attach the oil cooler to the engine mount instead. That would certainly be easier from a vibration point of view, but then I'd also have to come up with a way to duct a sufficient volume of air to it, while still fitting within the tight confines of the cowl. Hmm…

Well, I couldn't think of a better title for this post. I mixed up some epoxy and flox and glued the horizontal splice plates and rear hinges to the lower cowl:

What I should have done next was wait half an hour, then come back and remove the half-dried epoxy mess from the inside surfaces of the metal with a solvent rag. But I was tired so I went to bed instead. That meant I had to come back the next day with a grinder and tediously grind off all the dried epoxy. This also took some of the alclad off the aluminum, but that's okay since it will all be painted in the end.

Countersunk the outside and squeezed all the rivets… pretty standard stuff:

Here you can see how the epoxy grabs on to the holes drilled in the aluminum. Be careful to keep epoxy out of the hinge material. I used a squared-off piece of popsicle stick to dig the glue out from between the hinge segments, and I used a piece of steel rod coated in Boelube to keep it out of the hinge eyes.

Back on the airplane. Now the only clecoes in the fiberglass cowl are in places where there will eventually be some kind of removable fastener – either a camloc or a screw.

From the side, you can see that I have some work to do to even up the face of the cowl behind the spinner. I'll probably save that until later, since it won't affect what I'm planning to work on next.