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CHT's drop 50?!!!!

RV8Squaz

RV8Squaz

Well Known Member
Yesterday I took my airplane up for a test flight after installing my repaired LSE Plasma III and I'm very happy with the results. Overall, my CHT's dropped about 50?F.

For background info, see this thread, particularly my last post, message #66 here:

http://www.vansairforce.com/community/showthread.php?t=140211&page=7

Before the repair, my temps would hit 410-425 by 5000' during climb and I would have to level off and let things cool before continuing the climb. In cruise the temps would settle right around 400? running an excessively rich mixture.

For my test flights, I wanted to try worst case conditions. I launched in the middle of the afternoon with the OAT at 92?. I flew two 30 minute legs, KFFC-KPXE-KFFC, with about 30 minutes on the ground at KPXE. On the second leg, after being heat soaked, I took off and climbed straight to 10,500 while maintaining 100 KIAS. The hottest it got was 385? In the climb and in cruise the hottest cylinder settled at 360 at peak EGT mixture. I tried various altitudes and mixtures and generally saw 345-360?. VICTORY!!!

I want to thank Scott Card again for his original posts. My problem and resolution ended up being IDENTICAL to his situation. His posts and the other contributors to the connected threads have been especially helpful in getting though this. Thank you!
 
How about that! I'm seeing similar results with a borrowed unit. Ours hasn't gone back to Klaus yet, but probably will soon.
 
Talked to the Lycoming tech rep at Oshkosh, and at least got the O-320, maximum allowed sustained CHT is 435. Don't remember peak allowed CHT.
 
If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?

I checked the other thread, just didn't see much posted except the bad capacitor.
 
rayagriflite said:
If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?
Click to expand...

Standard setup check from the manual. Run it at 1000 RPM or so. Point a timing light at the marks. It should show base timing (20 or 25 BTDC depending on engine model) with the MAP sensor hose disconnected and open to the atmosphere. If your timing is advanced, you have a bad box.
 
rayagriflite said:
If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?
Click to expand...

I have the panel mounted Lightspeed timing display and it accurately displays the timing advance. Not sure though if it would display accurately if there was a fault in the brain box?

Fin
9A
 
Finley Atherton said:
I have the panel mounted Lightspeed timing display and it accurately displays the timing advance. Not sure though if it would display accurately if there was a fault in the brain box?
Click to expand...

Dunno Fin. I know the timing light doesn't lie ;)
 
The timing meter is reliable. I have one as well.
Dan, I don't think at idle it will read 20 degrees or 25 degrees. It is usually advanced quite a bit at 30 or more.
If you disconnect the manifold pressure line from the controller it will read low, usually 16 degrees. A quick check without using a timing light, and the associated danger, is to just disconnect the manifold pressure line while the engine is idling. You will notice a very substantial drop in RPM's if it is working correctly. If it is stuck at the high advance, there will be no change in the idle rpm's.

Vic
 
From Lightspeed manual.......

36
7.3: TIMING TEST
USING A STROBE LIGHT
To verify proper operation of the ignition system, you can check ignition timing using
a strobe light, automotive style, both on your new ignition and, should you still have
one, on the magneto. The magneto timing should be set to the manufacturers specs.
LSE Timing Values for Plasma CDI
:
Engines Normally Timed at 25 degrees BTDC:These are usually engines with compression ratios less than 8.7:1.

At idle the strobe light should indicate 40º ± 2º when the manifold pressure hose
is connected and 21º ± 2º when disconnected.
 
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vic syracuse said:
The timing meter is reliable.
Click to expand...

It's risky to assume the meter is accurately indicating what the engine is receiving. Although the electronics may be perfectly reliable, the indication is dependent on installation accuracy; garbage in, garbage out. For example, a Hall effect module can be rotated at will, changing the delivered timing, but the cockpit indication will not change. Misplaced magnets or a rotated sensor board will have the same effect.

A timing light displays actual crank position at the time of spark delivery.

Dan, I don't think at idle it will read 20 degrees or 25 degrees. It is usually advanced quite a bit at 30 or more.
Click to expand...

Yes, with the MAP hose connected.

If you disconnect the manifold pressure line from the controller it will read low, usually 16 degrees.
Click to expand...

Just reviewed the manual. I stand corrected, sorta. It says....

16 +/- 2 for 20 degree engines, 21 +/- 2 for 25 degree engines, plus one degree for every 1000 feet above sea level.

A quick check without using a timing light, and the associated danger, is to just disconnect the manifold pressure line while the engine is idling. You will notice a very substantial drop in RPM's if it is working correctly. If it is stuck at the high advance, there will be no change in the idle rpm's.
Click to expand...

That's a sensible approach to a quick check.

Oddly enough, the manual's instructions for a quick check are....

If you are using a remote timing indicator, you should see the timing retard to maximum retard, about 2 degrees less than Data Plate Timing (if you are near sea level). Reconnect your manifold pressure line after this test.

...which would be 18 or 23, plus the additions for altitude.
 
LSE Timing Marks

I have been reading this thread with interest. Lately I have had several incidents of backfire during start. I have checked the timing of the Slick Mag and it is right on and shows a standard 100-120 rpm drop during check.

I have never checked the timing of the LSE Plasma III installed on the top plugs. Perhaps I have been negligent in not checking the LSE ignition timing before but my engine has been running so good that it has been ignored.

I read in the manual that the "Factory timing marks should be duplicated twice, 120 degrees and 240 degrees from TDC" on 6-cul engines. (pg. 36) I have not seen anywhere what is recommended for making these timing marks. Is it a piece of tape of some sort or is a permanent black ink marker sufficient?

I am going to buy me a timing light this coming week. Is there a type and brand that is recommended?

Any help and suggestions anyone can make to steer me in the right direction during this process would be greatly appreciated.
 
DanH said:
Standard setup check from the manual. Run it at 1000 RPM or so. Point a timing light at the marks. It should show base timing (20 or 25 BTDC depending on engine model) with the MAP sensor hose disconnected and open to the atmosphere. If your timing is advanced, you have a bad box.
Click to expand...

Dan, have you actually gotten behind prop with engine running to check timing this way?
 
Van provides one cowl and one theoretical cooling system for all engines from 0320 to 0360 180HP to 0360 200 HP with the RV-8.

My CHT's with 0360 180 HP do not exceed 380 even with OAT in 90's unless it is a hot engine take off.

The problem I have is front to rear spread, the front cylinders are running 20-25 hotter than rear.

Will removing the cylinder baffle deflectors at #1 and #2 make a difference, don't want to do it unless it will make a difference.

Has anyone done it?
 
If you are going to run out and buy a timing light, stick with one that does not have an advance knob on the back - they have been known to introduce errors.
 
Ivan Kristensen said:
I have been reading this thread with interest. Lately I have had several incidents of backfire during start. I have checked the timing of the Slick Mag and it is right on and shows a standard 100-120 rpm drop during check.

I have never checked the timing of the LSE Plasma III installed on the top plugs. Perhaps I have been negligent in not checking the LSE ignition timing before but my engine has been running so good that it has been ignored.

I read in the manual that the "Factory timing marks should be duplicated twice, 120 degrees and 240 degrees from TDC" on 6-cul engines. (pg. 36) I have not seen anywhere what is recommended for making these timing marks. Is it a piece of tape of some sort or is a permanent black ink marker sufficient?

I am going to buy me a timing light this coming week. Is there a type and brand that is recommended?

Any help and suggestions anyone can make to steer me in the right direction during this process would be greatly appreciated.
Click to expand...

I was having kick backs like you but no more. I stopped using electronic ignition for start and use impulse coupled mag only.

This is with Robert Paisley's ignition system.
 
Kick back during start.

David-aviator said:
I was having kick backs like you but no more. I stopped using electronic ignition for start and use impulse coupled mag only.

This is with Robert Paisley's ignition system.
Click to expand...

That is very interesting! I tried starting on the electronic ignition only and did experience a small kickback thinking that it might be caused by the Mag. Doing it your way would require that you have an impulse coupling on the Mag, which I do, so that would be something to try.

I would really like to get rid of the Impulse coupling Mag and go with one without which would require all engine starts to be done on the electronic ignition only. This is what I understand Vic Syracuse and others are doing due to trouble with the Slick impulse coupling.

Perhaps Vic can chime in here and give us his experience?
 
My dual-LSE II setup would kick back once in a while too, so I modified my routine to start cranking with ignition off until prop swings 1/2 a revolution and then turn on both ignitions. That works every time. Of course, this only works with separate ignition switches and start button...
 
Options

Ivan Kristensen said:
That is very interesting! I tried starting on the electronic ignition only and did experience a small kickback thinking that it might be caused by the Mag. Doing it your way would require that you have an impulse coupling on the Mag, which I do, so that would be something to try.

I would really like to get rid of the Impulse coupling Mag and go with one without which would require all engine starts to be done on the electronic ignition only. This is what I understand Vic Syracuse and others are doing due to trouble with the Slick impulse coupling.

Perhaps Vic can chime in here and give us his experience?
Click to expand...

You may use a 6393 retard breaker slick mag in combination with a slick start module for safe smooth starting. Also, the impulse mag can be used , just be sure and check the impulse flyweights and rivets as per Slicks SB. If nervous just do it every 200 hours. Not a big deal either way. The slick start will boost starting voltage up to 300% only while the starter is energized. It can be used with either the impulse mag or the 6393 retard breaker mag.
 
Ivan, I responded last night but it came back. Sorry.

I don't think it is the EI. What brand do you have? An induction leak will
cause the backfire as well. Make sure plugs are gapped correctly, as a large plug gap will change timing.

Yes, I have the Plasma III and a non impulse mag. Seems to work great.

Don't hesitate to call.

Vic 404-307-5133
 
Timing Light / Marker

Ivan Kristensen said:
I have been reading this thread with interest. Lately I have had several incidents of backfire during start. I have checked the timing of the Slick Mag and it is right on and shows a standard 100-120 rpm drop during check.

I have never checked the timing of the LSE Plasma III installed on the top plugs. Perhaps I have been negligent in not checking the LSE ignition timing before but my engine has been running so good that it has been ignored.

I read in the manual that the "Factory timing marks should be duplicated twice, 120 degrees and 240 degrees from TDC" on 6-cul engines. (pg. 36) I have not seen anywhere what is recommended for making these timing marks. Is it a piece of tape of some sort or is a permanent black ink marker sufficient?

I am going to buy me a timing light this coming week. Is there a type and brand that is recommended?

Any help and suggestions anyone can make to steer me in the right direction during this process would be greatly appreciated.
Click to expand...

Here's a good, inexpensive timing light from Amazon - https://amzn.com/B000EVYH72

Screen%20Shot%202016-10-17%20at%2008.29.29_zpse35yerwh.png


I make marks with orange torque seal but you could also use a sliver sharpie or something like that.
 
f14av8r said:
Here's a good, inexpensive timing light from Amazon - https://amzn.com/B000EVYH72

Screen%20Shot%202016-10-17%20at%2008.29.29_zpse35yerwh.png


I make marks with orange torque seal but you could also use a sliver sharpie or something like that.
Click to expand...
Do not buy the light that has timing read out or control. The Lightspeed ignition uses multi discharge spark and wasted spark sequence and will screw with the computer algorithm in the light. You want the standard light with no fancy adjustable capabilities. I think the one that is selected in this picture is correct but just be advised not to select the other 2 optional choices at the bottom of the page.
 
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Timing light

Weasel said:
Do not buy the light that has timing read out or control. The Lightspeed ignition uses multi discharge spark and wasted spark sequence and will screw with the computer algorithm in the light. You want the standard light with no fancy adjustable capabilities. I think the one that is selected in this picture is correct but just be advised not to select the other 2 optional choices at the bottom of the page.
Click to expand...

I bought the above light today and it worked great. I found the timing to be at 36 degrees with the MAP connected. This is 5 degrees late according to Klaus' instruction manual considering our field elev. is 1040'

With he MAP disconnected the timing was perfect at 22 degrees, these values were consistent across all 3 coils. The manual states that this is the most important reading.
 
Weasel said:
Do not buy the light that has timing read out or control. The Lightspeed ignition uses multi discharge spark and wasted spark sequence and will screw with the computer algorithm in the light. You want the standard light with no fancy adjustable capabilities. I think the one that is selected in this picture is correct but just be advised not to select the other 2 optional choices at the bottom of the page.
Click to expand...

Good point Weasel. I should have pointed that out. Just the basic light is what you want!
 
Apologize for the thread drift, but after viewing this thread, I am wondering about the benefits of advanced timing (>25) at idle. I have control over my EI timing map and wondering if it is worth experimenting with advanced timing at idle.

Can anyone with experience discuss the benefits of more timing at idle vs the standard 25?

Larry
 
If you have the capability to adjust timing on the fly you can easily see what the engine likes at idle. In my case I just keep advancing the timing and the engine gets faster and smoother until it tops out. Just like in the old days when you disconnect the vacuum advance on your car and the RPM drops. There is a definite "happy place" if you take the time to find it.

I'm idling around 35 degrees, IIRC.
 
Toobuilder said:
If you have the capability to adjust timing on the fly you can easily see what the engine likes at idle. In my case I just keep advancing the timing and the engine gets faster and smoother until it tops out. Just like in the old days when you disconnect the vacuum advance on your car and the RPM drops. There is a definite "happy place" if you take the time to find it.

I'm idling around 35 degrees, IIRC.
Click to expand...

Thanks Michael. I'll play around with it a bit.

Larry
 
Idle is the easy one since you are really only looking for percieved "quality". Highest idle speed on the tach generally coincides with the smoothest feel, and there is zero chance of detonation or overheating. Once you have that set, you will probably have to turn the idle stop screw down to get the idle RPM back where you want it.

The only thing you have to pay attention to is a smooth transition to higher power settings. If you have a completely adjustable ignition like CPI, no issue. Not sure if other ignitions will allow you to max out the idle without dragging another part of the curve off optimum.
 
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