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  #11  
Old 08-16-2019, 02:50 PM
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Toobuilder Toobuilder is offline
 
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Thanks Marvin for the clarification. I've never seen RV-14 baffles and just assumed they were continuing with the same deficiency as legacy models. Good to see that they have addressed this.
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  #12  
Old 08-16-2019, 03:24 PM
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Quote:
Originally Posted by JHartline View Post
I even checked to make sure my #2 CHT wasn't indicating +20 degrees at ambient temps. I'm curious if the temperature spread is a common thing among the 14's or if I have a elusive detail to pursue.
A 20 F spread is pretty common fleetwide. Fly a 100 hours or so, then tinker with leveling CHTs if you wish. Won't hurt anything if you don't.

Quote:
My plane has an IO-390, dual P-mags, and AFP FM-150 fuel injection system and I have about 35 hours on the plane. Again, I'm mainly curious if other operators are seeing something similar.
Confirm you have a jumper wire between terminals 2 and 3 on each p-mag. Even with the jumpers installed (i.e. running curve A), CHT will rise as much as 4 F for every degree of ignition advance when mixture is near best power, and ~2-3 F or so per degree of advance at peak and LOP.

Need to run it harder than 50% for break-in.
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Last edited by DanH : 08-16-2019 at 03:27 PM.
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  #13  
Old 08-16-2019, 03:45 PM
JDA_BTR JDA_BTR is offline
 
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Good thought went and checked. My EFIS has then all as K - as it should be.
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  #14  
Old 08-16-2019, 04:18 PM
JHartline JHartline is offline
 
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Marvin,

Those CHT numbers are disgusting. I would never consider a 7-degree spread acceptable. That looks like a happy motor and I think you set a high bar to aim for. Was the modification you made intended to solve a specific issue or an effort to improve cooling flow overall? Did you have to modify the tension rods or make any other adjustments?

I don't have numbers for 11,000 but at 9,500 for a similar power setting mine looked like this:

PA - 9,500 DA - 10,960 OAT - +51F Percent power- 60%
20.0" / 2400 / 50 deg ROP / 167 KTAS / 8.8 GPH
CHT 1 - 341 CHT 2 - 359 CHT 3 - 330 CHT 4 - 317

Just one data point to show what temps I'm seeing. I don't have the EGT's but they were in the 1390-range I believe.

I'm not in a big hurry to do anything...just looking to get any true issues identified and handled before I wrap up phase-1. Thankfully they have been few. This CHT thing is one that can wait until I get some more time on the engine as you and others mentioned. I had not thought about that spacer (CB-00010) being Van's answer to the "washer" trick but that is what it appears to be.



Lots of great info on this today. Thanks you guys for your insights.
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  #15  
Old 08-16-2019, 04:32 PM
JHartline JHartline is offline
 
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Thanks Dan. I'm running the A-curve and clocked at 4-deg after TDC right now. I feel like break-in is pretty much done but I'm still operating at least 60% as much as possible. Temps are stable and oil use has dropped.

I love it when the solution is to go fly more
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  #16  
Old 08-16-2019, 04:34 PM
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M McGraw M McGraw is offline
 
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James,

The modification was extremely minor as shown below. I simply did not like that it was on top of the comb because that is a leak. I mentioned it on VAF and DanH suggested I bend and move on (He should be a hand model his picture was better than mine)

I would say your 20 degree spread is probably very normal at 35 hours. Give it 100 hours before doing much.

Before:

After:
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Last edited by M McGraw : 11-24-2019 at 09:16 PM. Reason: Updated picture links
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  #17  
Old 08-16-2019, 04:40 PM
JHartline JHartline is offline
 
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Marvin, thanks for the photo. Makes sense now.
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  #18  
Old 08-16-2019, 05:55 PM
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Quote:
Originally Posted by JHartline View Post
Thanks Dan. I'm running the A-curve and clocked at 4-deg after TDC right now. I feel like break-in is pretty much done but I'm still operating at least 60% as much as possible. Temps are stable and oil use has dropped.

I love it when the solution is to go fly more
Excellent. Yes, fly more and run it harder. Need combustion pressure to apply radial ring pressure.
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  #19  
Old 09-23-2019, 08:49 PM
Contrailing Contrailing is offline
 
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Sorry if I'm kicking a dead horse... my angle valve IO360 in my 7 has the number 2 cht running 15-18 degrees above the others even after 550 hours ttsnew. Ran into a fella at OSH who after hearing my complaint said he's heard numerous guys address this same issue with drilling a couple small very calculated holes in the no. 2 cylinder head area to normalize the cht with the others. Is this "snake oil" advice or what? Engine is injected and I thought of modifying the No. 2 injector port slightly larger to allow for more fuel cooling. Trying not to buy Gami injectors just yet.
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  #20  
Old 09-23-2019, 09:16 PM
JDA_BTR JDA_BTR is offline
 
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The problem in the 14 is that the ramp in front of cylinder 2 is on top of the fiberglass snorkel, with the baffle running down between the snorkel and the cylinder. So even if you did drill a hole down through the ramp, and into the baffle, it has to traverse the snorkel as well. And likely the area outside the baffle meaning you just make a worse air leak.

My arrow has a 3/4 inch tube that goes to the middle of cylinder 2 lower part to direct air straight there, so maybe if you really want some air the best way is to take off the baffle and snorkel, fit a piece of tube into a hole, and direct some air directly at the fins down there. Seems a chore.

I just can't come up with a clean way of getting more air to go through that slot between the snorkel and the cylinder. But maybe its not worth it for the time being. Lately my #1 is 10 higher than 3/4, and #2 is 15 higher than #1. All acceptable.
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