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  #31  
Old 02-25-2016, 03:01 PM
Jimzim Jimzim is offline
 
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Location: Arvada, CO
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You might consider repositioning the entry air ramp on the top cowl. I had very similar CHT problems until I moved mine forward. This really improved entry air volume and greatly reduced temps, especially #1. Just search this forum for more detail. Worked great for mr, FP 0-360, RV7. Easy fix!
Good luck, Jim
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  #32  
Old 02-25-2016, 03:13 PM
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Jesse Jesse is offline
 
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Quote:
Originally Posted by bluebrear View Post
Vern, Speaking with Marvel-Shleber, I found out that my carb has one of the richest jets installed. It starts out at .101" dia. Do you have any idea how much increase in the bore would be to attain?
Are you absolutely sure you're hitting the rich stop on the mixture?
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  #33  
Old 02-25-2016, 03:13 PM
PaulR PaulR is offline
 
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Location: Geneva, AL
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Default Drill

When I did mine I drilled it in steps and ended up at a #39 drill. 0.995. That took mine from a rich to peak increase of about 50 degrees to 175 degrees and helped the cooling a lot in the climb. I would think that if yours is in fact .101 now that the problem would be more in the baffling and timing.

Even after drilling out, if I climb at VX very long i will shoot past 400. I try to climb at nothing less than 100 knots unless it's necessary.


Mine does have 9:1 pistons in it also.

Someone mentioned the ramp on the inside of the cowl and I truly believe that this is an area that would really help the cooling. DanH and I have talked about it several times and he's posted about it also. I will change mine at condition inspection time just to see what difference it makes.
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  #34  
Old 02-26-2016, 10:33 AM
bluebrear bluebrear is offline
 
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Jim
Did you cut the dam out, shorten it and then replace a shorter section, thus moving that dam forward? If so, about how much forward?
Thanks
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  #35  
Old 02-26-2016, 11:08 AM
bluebrear bluebrear is offline
 
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Location: Bethel
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Would like some opinions about ambient temps affecting the CHT's. We're flying in Maine winter with these high CHT temps and concerned about increasing OAT's as the WX improves.
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  #36  
Old 02-26-2016, 11:20 AM
Kyle Boatright Kyle Boatright is online now
 
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My CHT's in cruise are typically ambient + ~280F.
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  #37  
Old 02-26-2016, 02:34 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
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I would say mine are pretty similar to Kyle's: ambient + ~280F will be my average across all 4 CHTs, though I'm usually running only 65% power when I'm economy cruising. I'm assuming they'd be higher if I try to cruise faster. In addition, if my oil gets really warm because it's a hot day, I think my CHT's will rise a bit beyond what the above formula above suggests. I'm still fighting some cooling issues I think, though I'm gradually finding baffeling improvements to help.
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  #38  
Old 02-27-2016, 05:37 PM
Jimzim Jimzim is offline
 
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Yep, I just used my Dremel to cut the ramp out, smoothed things up a bit, shortened it about an inch and a half as I recal, then glassed it back in. They say you should be able to make a fist and shove in through between the ramp and the cylinder. I'm there now. It was easy.
Jim
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  #39  
Old 02-28-2016, 04:10 AM
vic syracuse vic syracuse is offline
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Default Here's a reason

In an RV-9A I looked at yesterday the CHT probe was installed in the PRIMER port of the number 3 cylinder! That's a first.

Vic
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  #40  
Old 02-28-2016, 05:34 AM
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Jesse Jesse is offline
 
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Quote:
Originally Posted by vic syracuse View Post
In an RV-9A I looked at yesterday the CHT probe was installed in the PRIMER port of the number 3 cylinder! That's a first.

Vic
That's scary. That's an NPT thread port. Most CHT probes are strait threads, aren't they?
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