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Help Understanding the Baffling Mod

istrumit

Well Known Member
I have searched and found all of the threads regarding adding space behind cylinder #5 on the RV-10 so that that cylinder cools a bit better.

I have seen the idea of modifying the baffle with a hammer and with a little aluminum modification.

But, I have not seen a picture of the simple solution, adding a washer as a spacer.

Does anyone have a picture of that ?

I have managed to get all of my CHTs down quite a bit, except for #5, which has been stubborn.
 
I have searched and found all of the threads regarding adding space behind cylinder #5 on the RV-10 so that that cylinder cools a bit better.

I have seen the idea of modifying the baffle with a hammer and with a little aluminum modification.

But, I have not seen a picture of the simple solution, adding a washer as a spacer...

The root of the problem is that lycoming cylinders are designed to work together, with one cylinder providing the air path for both. In that respect, the washer trick fails to fully address the real issue and creates new ones. Calling the washer trick a "solution" is like saying a mini spare on your car is the "solution" to a nail in your full sized tire. It gets you where you want to go, but the car will not perform as designed.
 
Calling the washer trick a "solution" is like saying a mini spare on your car is the "solution" to a nail in your full sized tire. It gets you where you want to go, but the car will not perform as designed.

Good analogy Mike.
 
so you guys don't like the washer. can you share your preferred methods?

Here is one way, but the baffle would have to be removed for this. It provides air to an additional 15 in^2 of fins. The flashing should be removed and head polished at the same time. Why have the fins and allow them to be blocked off? This provides a .2 X 2" slot for air flow, at 5-15 in-h2o pressure that is a lot of air directly applied to cooling.
K0mRLnGWqHlPQoMD7jUtI7L0Lm4jErtwd0pQaTVLp_2mf0qtZP0LbBle_Q80vj9FrJqjUBgsuS3QVAkMGnUvdqncYoFqBVWnvneAi62qE_4kTYotgJ4OgYc2uQyu8jkhrJv_Fl_Hh2InfZ7eBJWlhfzuo-sJdrM55PxU7QCrfeu-hmfy-c5m_qwXlvIooZ8LPbt94kvVKiijne8niJSeDouNOM2H431MVIOr2QlVbZnf5hQERmtkm3xXaBs2cjbnryLXE6QOCvTybo-rqhEP5Eae7spj3djBjRYyxXzeQxxNpJhkaywqLD6Pb7k0JEnf5Fyn96SzPbCj2RTzguenfqzClCeTgeMTDefBqam1Pzkm5DLCp73mR-yhUYTWTSLLO-yEa05q4iWrf71UU8ciWSdHK-pYvMWFu9hpU0Ag20MMde7PCYMuavrSrFg8AtxsTI9rgt0bqSXJr-PsQg3AQmUg3oNcSfuPbWlNxFVwKgvp-yVIoASMTJ2IOAtapG-jBVoV-nUcb6-sDZ_kP92COmcca320nNDEAIlhXgE-vun_OUpUz_NTXrTrOa7MV_5oPpsDe5o6d2gpkTDI-W_mMIPDd61Yjruechn734RUNBL5eX3oqF_aoiMeXjXUOCG38bNm4r6SvU505UZBfsfMXqBLVvcy4fBCMc3YgAQacA=w546-h728-no
 
Here is one way, but the baffle would have to be removed for this. It provides air to an additional 15 in^2 of fins. The flashing should be removed and head polished at the same time. Why have the fins and allow them to be blocked off? This provides a .2 X 2" slot for air flow, at 5-15 in-h2o pressure that is a lot of air directly applied to cooling.
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This is what I did when the washer didn't do the trick. I was actually able to do it without removing the baffle on my o-320, but by the time I finished it would have been just as quick to remove it. Brought temps right in lone with the others and can climb all day now.

Chris
 
so you guys don't like the washer. can you share your preferred methods?

A search for "... #3 cooling..." Will reveal a plethora of threads on the subject, but Bill's solution is the jist of it. In addition, both DanH and I in particular have worked the issue and posted results.
 
so you guys don't like the washer. can you share your preferred methods?

There are two or three excellent threads to review, showing a variety of bypass ducts like above. Those ducts can also be found on some certified airplanes.

Next on the list is a strip of sheet or plate material where the washer would go (screw goes through it). That spaces the baffle tin out away from the head like the washer, but blocks the large (and useless) leakage area in the immediate vicinity of the screw.

Last is a washer, and a wad of silicone to block the useless leakage area.

The latter two also result in some leakage out the sides of the lower wrap, while the duct keeps the wrap hard against the tips of the lower fins, assuming a little care.
 
I solved my CHT problem on # 3 with the exact solution mentioned in post 6 above. Haven't had any CHT problems since. Before I went this route I tried the washer route and no joy. Didn't really make any noticeable difference for me. It was a pain removing the baffling but worth it for the fix that worked. This fix worked so well I also spent a little time adding a similar fix to the #2. It was not running as hot as 3 but still it was a little toasty for me. It worked there too. Now I can take off on a hot summer day and climb to 10K and the max temps are about 400 then it starts falling again as I continue the climb. I should add that the 400 max temps are with a good climb rate too. My usual practice is once I'm at 1000 ft. I most always ease off to a cruise climb and my temps easily stay south of the 400 mark.
 
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Check out these from a certified Grumman Tiger...#3:

Grumman%20Tiger%20RR.jpg


Grumman%20Tiger%20RR%20Top.jpg


IO-390, added after the hammerformed duct didn't flow quite enough to satisfy me:

IMG_1233.jpg
 
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Many of us have followed Dan's lead on this and it flat out works. It's really not a "fix" as much as simply the right way to do it. Its what the Lycoming needs to operate as designed.

What I can't understand is why Vans (the "total performance people) continues to offer a flawed baffle design.
 
Check out these from a certified Grumman Tiger...#3:





And #3 on a parallel valve Mooney:



IO-390, added after the hammerformed duct didn't flow quite enough to satisfy me:


I am trying to look at some of these pictures but clicking on the photo, it says the file can not be found. Is there any other location I can search for them?
 
Is it only me that can not view the pictures or the pictures are deleted?

I have signed up for photobucket but I get an error when trying to click on it to view it.
 
Is it only me that can not view the pictures or the pictures are deleted?

I have signed up for photobucket but I get an error when trying to click on it to view it.

Use Firefox and get the add in for the photo bucket workaround. It may still work, last time I used it was a few weeks ago. The picts pop up like normal - then screen copy them if worthy.
 
Use Firefox and get the add in for the photo bucket workaround. It may still work, last time I used it was a few weeks ago. The picts pop up like normal - then screen copy them if worthy.

Thanks Bill, still the same with Firefox.
 
I just did my first flight on my RV8 about 30 day ago. All went well ( usual small Items). I am at 19 hrs and was hoping the CHT's would come down . They are fine in cruse 24 square or even 25 square 360 's. but 1,3 and sometimes 2 go over 400 to 415 on the first climb even at very shallow high speeds. I check timing, I checked baffle leaks, I tried the washer trick. As the temps get warmer here in northern Ohio, My fear is the CHT's will still be a problem.

So I bit the bullet and did the " baffle mod behind number three, and cut down the dams in front of 1 and 2.

When the winds stop blowing at 35 to 40 and the rain quits I will report the results.
 
Flew my 8 with the # 3 baffle mod yesterday. I appears to have worked well. # 3 is now right in line with the rest and appears to have dropped 20 to 30 deg. F.

I also have been cutting down the air dams in front of #1 and #2. 2 is now good but 1 is still a little high, I will cut it down. Now at hr 21 on phase 1.
 
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