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  #1  
Old 03-15-2016, 08:03 PM
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walter walter is offline
 
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Default Sealing Lower Inter-cylinder Baffles

I'm at the point where I should take care of any needless air gaps in the lower inter-cylinder baffles. There are a few gaps that I think should be sealed with silicone or other because the gap doesn't seem like it's doing anything more than letting too much cooling air pass by the cylinder fins. I've marked the areas with arrows that I think should be sealed in the images below. Any comments would be helpful.





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  #2  
Old 03-15-2016, 08:07 PM
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Toobuilder Toobuilder is offline
 
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Yep. I did the same thing on the Rocket. Dont be afraid to bend the tabs near the cylinder base nuts toward the barrel to tighten the gap a bit too. Speed tape and rtv go a long way toward sealing all these gaps.
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  #3  
Old 03-15-2016, 08:24 PM
BillL BillL is offline
 
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+1 me too. I sealed all the areas you show, and some more.
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  #4  
Old 03-15-2016, 08:29 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
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Quote:
Originally Posted by Toobuilder View Post
Speed tape and rtv go a long way toward sealing all these gaps.
What's speed tape, Mike? Is it something that holds up to heat pretty well?
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  #5  
Old 03-15-2016, 09:56 PM
tx_jayhawk tx_jayhawk is offline
 
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Walter,

Turn the lights out until it's pitch black and shine a flashlight in between the cylinders and look underneath. Light will shine through the gaps. YOu'll be amazed at all the gaps that are there, and you want to seal them all.

All told, I seem to recall it made 10 or 12 degrees difference in CHT on my 7A.

Scott
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  #6  
Old 03-15-2016, 10:58 PM
rockwoodrv9 rockwoodrv9 is offline
 
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I am blown away that such small gaps make any difference at all. I have started my baffles and I will have a plenum and seeing threads like this make me wonder how I will ever get my plane finished. I had the fuselage and wings done before I knew there even were baffles!

Is it poor cooling that is the result of the leaks? Speed? Maybe a bit of both?

Thanks for the pictures. I can see these baffles are going to take more time than I guessed.
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  #7  
Old 03-16-2016, 06:48 AM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by alpinelakespilot2000 View Post
What's speed tape, Mike? Is it something that holds up to heat pretty well?
Also known as "300 MPH tape" or "mach tape", it is an aluminum foil with an adhesive that comes on a roll (like duct tape). It makes good temporary (and in some cases permanent) repairs to small holes in aircraft skin. I've seen some C-130's that seemed to be held together with the stuff. Quality varies, but the aircraft stuff is a fairly heavy guage and has great adhesive.
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  #8  
Old 03-16-2016, 06:54 AM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by rockwoodrv9 View Post
I am blown away that such small gaps make any difference at all. I have started my baffles and I will have a plenum and seeing threads like this make me wonder how I will ever get my plane finished. I had the fuselage and wings done before I knew there even were baffles!

Is it poor cooling that is the result of the leaks? Speed? Maybe a bit of both?

Thanks for the pictures. I can see these baffles are going to take more time than I guessed.
If the air is going anywhere but through the fins or the oil cooler, it is costing you cooling and adding drag. It does not take much time to do the inner baffles - especially if the engine is still on the stand. The more "stuff" you add to the engine, the harder it gets.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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  #9  
Old 03-16-2016, 07:19 AM
Tom Martin Tom Martin is offline
 
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A piece of flexible plastic tubing taped to the end of your caulking gun will help to get the RTV where it belongs.
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  #10  
Old 03-16-2016, 08:06 AM
Kent Ashton Kent Ashton is offline
 
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Aluminum-colored silicone caulk from the home stores will fill gaps very well and blends with the engine color. It can also be used to make cylinder wraps by squeegeeing it into fiberglass cloth and cutting to size. Holds up well.
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