Baffling

[Brandontwalker]

I have found that baffling can be quite baffling. Does anyone have advice for me as to the best way to rebaffle a M20J? I am using the fiberglass reinforced silicone material and attaching with the metal baffling strips. The plan is to use the current baffling as a template, but what I have is not perfect. What about overlaps? I have seen some attached with rivets or screws and washers and some overlaps left loose. My overlap are currently secured together with rivets and it is evident where bunching is occurring in the corners and allowing air to escape. I would love to hear your solutions.

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[Jim F]

Hi Brandon,

There is a little bit of art to getting everything to fit up well. First remember that the top cowl presses down on the seal so if you make everything align with cowl off then when the cowl is on you will get bulging and air loss. On the rear right and left overlap to the horizontal sections above the rocker covers these should stay free to move on each other because of the top cowl compression. For hardware there are wide head pop rivets, solid rivets with backer strips and for seal to seal you can find a low profile wide head aluminum screw sets. Think about the high speed air coming in the cowl openings and if that airflow can grab a piece of baffle seal it will.  Over laps should be set so air flow holds the flap down. If you get a bulge in a straight section you can cut down the center of the bulge and overlap based on airflow. I found a pic of the wide head screw. 

Jim F

[Guest]

2 hours ago, Brandontwalker said:

 

I have found that baffling can be quite baffling. Does anyone have advice for me as to the best way to rebaffle a M20J? I am using the fiberglass reinforced silicone material and attaching with the metal baffling strips. The plan is to use the current baffling as a template, but what I have is not perfect. What about overlaps? I have seen some attached with rivets or screws and washers and some overlaps left loose. My overlap are currently secured together with rivets and it is evident where bunching is occurring in the corners and allowing air to escape. I would love to hear your solutions.

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You might want to check with Guy Ginby at www.csobeech.com He makes nice pre cut baffle material in a number of colour, he includes all rivets and fasteners you could ever need.

Clarence

[StevenL757]

Seconded.  Guy sent me custom-cut baffles a few years ago, and they've held up extremely well.  I would order them again in a minute.  The fit was spot-on, and extremely well-measured.  My CHTs are never more than about 10 degrees apart (yes, 10), so I can't help but think the quality of baffle had a lot to do with that spread.

Steve

[LANCECASPER]

Make that three for Guy Ginby. I just did mine last month. Just did the first decent flight since that yesterday. The rear cylinders are now much closer in temp to the front and middle cylinders.  n77gb@msn.com

[DonMuncy]

6 hours ago, Brandontwalker said:

 

I have found that baffling can be quite baffling. Does anyone have advice for me as to the best way to rebaffle a M20J? I am using the fiberglass reinforced silicone material and attaching with the metal baffling strips. The plan is to use the current baffling as a template, but what I have is not perfect. What about overlaps? I have seen some attached with rivets or screws and washers and some overlaps left loose. My overlap are currently secured together with rivets and it is evident where bunching is occurring in the corners and allowing air to escape. I would love to hear your solutions.

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On my K model, you can look in the oil filler door and get a pretty good look at what the baffling is doing. On the J, can you use a mirror and light to see what is taking place when the cowling is on. If you have a "wrinkle", you can slit the baffle seal right in the center of the wrinkle and let the two sides overlap. You really don't want to affix those two sides together, as they need to be able to move as the cowling pushes them down.

[cnoe]

+1 on Guy's baffle sets. 3 1/2 years later and still look/work great!


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[jetdriven]

1 hour ago, cnoe said:

+1 on Guy's baffle sets. 3 1/2 years later and still look/work great!


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+1. 4 years here still looks like new 

[Danb]

Approximately how much does the kit from Guy cost, I have a Bravo 

[LANCECASPER]

$475 plus shipping and he throws in silicone valve cover gaskets. He sent the wrong valve cover gaskets at first but then sent the correct ones.

[StevenL757]

Here's a website (credit - Mr. Jim Kerr), showing his Mooney N252Q going through the process of replacing his baffles with Guy's seals.  A great writeup, with pictures showing the process.  The article is from ~2006, but excellent information.

http://www.n252q.com/2007/09/baffled-about-baffling.html

Steve

[cnoe]

$475 plus shipping and he throws in silicone valve cover gaskets. He sent the wrong valve cover gaskets at first but then sent the correct ones.

That's more than twice what my set (M20J) cost in 2014. I'd expect the price to have increased but... Also, his valve cover gaskets are awesome. I imagine your IO550 set is more substantial and more costly than an IO360 set.


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[LANCECASPER]

In 2014 I bought a set for a Mooney Encore (M20K) it was around $400 with no valve cover gaskets.

There are over 20 pieces for the M20M baffle set. It's not cheap but it's great quality and all pre-cut and in my opinion definitely beats trying to make your own.

[Brandontwalker]

Okay, I knocked it out tonight. I appreciate the recommendations on Guy, but I already had materials from Spruce in hand. In any event, it was only a four beer (and one hamburger) job. It was far easier than expected. The toughest part was drilling out all of the rivets, and that wasn't so bad. The results were terrific if I say so myself.


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[carusoam]

Nice photos from inside the cowl!

Best regards,

-a-

[jetdriven]

Don't forget all the baffle seal on the front corners and under the spinner. That's all high pressure air in there and it will escape through any poor fitting seal. 

[Bravoman]

I'm having my baffling and seals from Gee Bee installed now. I'll report back soon on the improvement with Chts. 

Regards, Frank

[TheTurtle]

15 hours ago, GEE-BEE said:

1977 M20 J 175.00

( RAM AIR )

1978 ON UP M20J 175.00

M20K-231 275.00

M20K-252 275.00

M20M/ BRAVO 475.00

M20R 375.00

 

RIVET COLORS

WHITE-SILVER-BLACK

 

ALL DIE CUT TO ORIGINAL OEM SPECS

AMS3320-.093

 

YOU CAN TAKE STRAIGHT MATERIAL AND MAKE A CORRECT FIT

I dont see M20F model listed above?  Price?

[INA201]

I was just perusing the Vansairforce site and looking at how they baffle their engines. Seems there may be some merit to baffling around the front of the engine as well. My thoughts are that you may gain a little more pressure in the engine compartment thus you could pull your cowl flaps in tight to gain a couple of those elusive knots in speed while being cooler.  The first photo is the Vans, while the last two are my J.  Anyone have any experience or thoughts? 

[Guest]

18 minutes ago, INA201 said:

I was just perusing the Vansairforce site and looking at how they baffle their engines. Seems there may be some merit to baffling around the front of the engine as well. My thoughts are that you may gain a little more pressure in the engine compartment thus you could pull your cowl flaps in tight to gain a couple of those elusive knots in speed while being cooler.  The first photo is the Vans, while the last two are my J.  Anyone have any experience or thoughts? 

I don't think that the Vans piece is required.  Sealing every possible hole in the Mooney baffles will do just as well.  Some form of sealing from the front right baffle to the alternator will help.  Also the alternator cooling flan and cooling tube are not Mooney installations.  Alternator cooling flow should be from the front and out the back below the cylinders.

Clarence