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12-25-2013, 05:16 AM
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Join Date: Jul 2007
Location: Pembrokeshire, UK
Posts: 224
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GalinHDZ
I had a similar issue after my first annual and it was due to the fact I used the centre of the starter as my TC1 ref instead of the dot on starter ( see my log photos). Retimed to the correct ref and my numbers all came back to normal - see below.
One you have sorted the issue out I would definitely lean out as the benefits are win-win on the graph shown above by RV10inOz - less fuel $, less CHT and less stress on the engine.
My annual average numbers for ASP IO-360, Catto 3 blade, Dual P-Mags with auto plugs at 2000ft AMSL are 2200 RPM, 138 kts(IAS), 6.3 US Gal/Hr (24 litres/hr) and CHTs sub 300 in winter around 315 in summer all at about 30 deg LOP. I could cruise faster but I have to watch the $$ 
__________________
Bob Ellis
www.rv-8.co.uk
G-JBTR Having a ball flying this wonderful machine
Donation July 2016
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12-25-2013, 06:14 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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__________________
Dan Horton
RV-8 SS
Barrett IO-390
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12-28-2013, 03:08 PM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by N941WR
Higher CHTs is very common when swithching from standard mags.
What numbers are you seeing?
Pull your plane in the hangar, turn off all the lights, put a trouble light under the cylinders and look for air leaks. I was able to drop my CHTs by 15 to 20 degrees by simply sealing all my LITTLE air leaks.
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Bill; After talking on the phone with you I changed the alternator blast tube from 1-1/2" to 3/4" (I didn't have the heart to close it completely off), changed the carb heat scat tube from 2-1/2" to 1-1/2" and the temperature problem is gone. I left the mag timing at TDC. Now all 4 cylinders run within 5F of each other with the hottest one (#4) running at 401F. You can call me a happy camper!
THANKS for pointing me in the right direction.

Last edited by GalinHdz : 12-28-2013 at 05:53 PM.
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12-28-2013, 06:41 PM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Yesterday I had my first flight since I installed my PMAG (one PMAG, one slick) and here are my numbers;
Slick on the left is timed right at 25 degree BTDC
PMAG on the right side is timed 2 degree ATDC
On the ground mag check I drop about 90 RPM on the left (slick) and 100 to 110 with the PMAG (I was hoping a better result with the PMAG. The MAG check in the air seems to be only 30 RPM drops on the PMAG and 40 RPM drop with the slick. I ran LOP and it was very smooth (50 LOP on the hottest cylinder) and I am within .2g between all cylinders. The CHT seem to be a tad higher compared to before but still very good, ROP is about 360-370 and LOP is 320-330. My CHTs have always been very close to one another.
The start from cold is within the first blade or so, very happy with that.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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12-28-2013, 07:08 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by GalinHdz
Bill; After talking on the phone with you I changed the alternator blast tube from 1-1/2" to 3/4" (I didn't have the heart to close it completely off), changed the carb heat scat tube from 2-1/2" to 1-1/2" and the temperature problem is gone. I left the mag timing at TDC. Now all 4 cylinders run within 5F of each other with the hottest one (#4) running at 401F. You can call me a happy camper!
THANKS for pointing me in the right direction.

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It was good talking to you and I hope your trip was enjoyable!
Is there anyway you can switch to an RV style carb heat on your KIS TR-4 Cruiser and completely eliminate the carb heat scat tube? That might help lower your CHT's even more.
Here is a picture of the carb heat on my O-360. There is no ram air with the RV carb heat and the air is drawn in along the back of this cuff.

The heat muff can be found here.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Last edited by N941WR : 12-28-2013 at 07:10 PM.
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12-28-2013, 07:31 PM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by N941WR
It was good talking to you and I hope your trip was enjoyable!
Is there anyway you can switch to an RV style carb heat on your KIS TR-4 Cruiser and completely eliminate the carb heat scat tube? That might help lower your CHT's even more.
Here is a picture of the carb heat on my O-360. There is no ram air with the RV carb heat and the air is drawn in along the back of this cuff.

The heat muff can be found here.
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I had not seen this before. But if it doesn't need ram air, then why can't I just eliminate the scat tubing to the heat muff and let the heat muff draw air from inside the engine compartment instead of pulling it from the outside?

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12-28-2013, 07:39 PM
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Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
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Quote:
Originally Posted by GalinHdz
I had not seen this before. But if it doesn't need ram air, then why can't I just eliminate the scat tubing to the heat muff and let the heat muff draw air from inside the engine compartment instead of pulling it from the outside?

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You can. The question is whether the temperature rise without the shroud is sufficient to prevent and/or melt carb ice.
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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12-28-2013, 08:34 PM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by Kyle Boatright
You can. The question is whether the temperature rise without the shroud is sufficient to prevent and/or melt carb ice.
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No, not removing the shroud just removing the scat tube that connects the shroud to the plenum. Air will flow from inside the hot engine compartment, get heated even more through the shroud before going on to the carb.
I then cover the hole in the plenum, where the scat tube used to connect, increasing the amount of cooling air directed at the cylinders.

Last edited by GalinHdz : 12-28-2013 at 08:41 PM.
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12-28-2013, 09:19 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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If you have a carb temp probe, document your carb and CHT temps in various flight configurations. Then change your carb heat setup and see what the difference is. I would expect you MAP to go down due to your loss of ram air but not significantly enough to keep you from flying.
Let us know what you do and how it works out.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Last edited by N941WR : 12-29-2013 at 07:25 AM.
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12-29-2013, 04:00 AM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by N941WR
If you a carb temp probe, document your carb and CHT temps in various flight configurations. Then change your carb heat setup and see what the difference is. I would expect you MAP to go down due to your loss of ram air but not significantly enough to keep you from flying.
Let us know what you do and how it works out.
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I have a carb temp probe so this is something I will do when I get back from my trip. THANKS for the idea and I will let you know what numbers I get.

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