Engine Baffle Install

jimbo · #1 02-06-2012, 12:26 PM

The Cyl #3 aft baffle, part CB-907A, is a b.... to put in place. What do people do, remove the cyl 3 fuel line first? or any tips out there? Maybe this is another of those rights of passage things.

Also, once in place I really don't want to keep removing and re-installing it to trim the top for the contour of the cowling. Has anyone had luck with trimming in place? If so what tools have they used (I'm thinking compressed air shears, or hack saw then plenty of filing).

I'm just getting started on this baffling job and any tips would be appreciated.

Jim
RV9A
0320 w/ Vans baffle kit

Pat Hatch · #2 02-06-2012, 02:57 PM

Jim,

Not sure what fuel line you're referring to, but you should remove the oil drain line from #3 cylinder and also remove the oil filler tube. Unscrew the tube and stuff a clean rag down the hole. This should help you fit the rear baffle behind #3 cylinder.

Most folks add an AN960 flat washer as a shim in between the cylinder fins and the baffle at the screw that attaches the baffle to the engine. This gives a little spacing between this baffle part and the rear of the #3 cylinder and supposedly helps keep #3 cylinder a little cooler. Fitting the baffles can be frustrating, but it'll all work out. Good baffling!

Pat Hatch · #3 02-06-2012, 04:24 PM

On to the second part of your question: you can probably do most of your trimming in place with a pair of hand shears (initially). You're looking for about ?" of clearance or slightly less. Use your finger-width gauge and feel between the baffle and the top cowl. You will probably have to pull the parts off a few times to get everything cleaned up and then etched and alodined, etc. It gets easier each time. Anyway, that's the way I did it but there are many variations.

Tip: if you're putting your oil cooler behind #4 cylinder, you will want to beef up the corner behind #4 and possibly brace the rear baffle behind #4. There are many ways to do this and well documented here. Do a search on "baffles" and you'll get some great photos.

jimbo · #4 02-06-2012, 05:16 PM

Pat,

Maybe I am mistaken. The line I was referring to is 3/8 inch or so diameter and goes from under the cylinder to the head of the cylinder. Not being an engine guy maybe this is the oil drain return? Anyway it is in the way and gotta come off.

Thanks for your help. Totally understandable.

Jim

N941WR · #5 02-06-2012, 06:12 PM

Quote:

Originally Posted by jimbo

Pat,

Maybe I am mistaken. The line I was referring to is 3/8 inch or so diameter and goes from under the cylinder to the head of the cylinder. Not being an engine guy maybe this is the oil drain return? Anyway it is in the way and gotta come off.

Thanks for your help. Totally understandable.

Jim

Yes, that is the oil return line Pat was talking about.

Here is another tip for fitting the baffles. Make sure to use a lot of RTV to seal them against the engine case.

(Click to enlarge)

Pat Hatch · #6 02-06-2012, 06:34 PM

Jim, yes, just loosen the AN flare nuts and pull these lines right off. You can re-attach after you're all done. The little flaps that go under the cylinders will be a lot easier to attach if these oil drains are removed. Here is a photo of the oil drains and filler tube that I found. This was during my baffle installation.

You can see how much this is going to open up this area to facilitate the baffle fitting.

jimbo · #7 02-07-2012, 08:00 AM

Pat,

The pic is worth a thousand words.

You mentioned etching and alodine-ing the baffle parts. Is this recommended even though everything looks like its alclad (except where the alclad is scratched off)? Whats that do to the alclad protection?

Haven't done this before.

Jim

Pat Hatch · #8 02-07-2012, 10:44 AM

Quote:

Originally Posted by jimbo

Pat,

You mentioned etching and alodine-ing the baffle parts. Is this recommended even though everything looks like its alclad (except where the alclad is scratched off)? Whats that do to the alclad protection?

Haven't done this before.

Jim

Jim, strictly personal preference and totally optional. I primed my airplane since I'm in Florida, and wherever I didn't prime (such as the fuel tanks and baffles), I just etched and alodined. I did most of my trimming with the baffles in position, but then I removed everything to smooth the cuts (Scotch Brite wheel), deburr, round corners, etc. Threw everything in the etching vat, then alodine, and done.

krw5927 · #9 02-07-2012, 10:56 AM

Quote:

Originally Posted by N941WR

Yes, that is the oil return line Pat was talking about.

Here is another tip for fitting the baffles. Make sure to use a lot of RTV to seal them against the engine case.

(Click to enlarge)

This picture is simply fantastic. What a clever way to determine how to trim baffle seals! A few paper clips on the baffle every few inches, put the cowl on letting it push the paper clips down as necessary, take the cowl off and bam!

This may be common knowledge but I've never seen it before and I think it's a great idea!