VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 02-16-2015, 11:27 AM
MikeyDale's Avatar
MikeyDale MikeyDale is offline
 
Join Date: Aug 2012
Location: Garden City Texas
Posts: 878
Default Plug Wire Clamp

I have a question for you more experienced builders or engine gurus out there. I am testing my engine and trying to iron out a plug fouling issue. I have Bendix mags (75 hrs since overhaul) and UREM40E tempest plugs with new harnesses. I have read extensively about all the plug fouling cures so I'm not really looking for advice there but I am curious about what might have caused the blackish look on my plug wires next to the edge of this adel clamp!



I used all the white silicone clamps that came with my new harnesses but needed to secure the wires to a few more places on the motor mount with regular adel clamps like the one seen here. After running the engine the first time, the blackish color appeared. I ran the engine a very short time just warm enough to do a mag check so I know it didn't get that hot there. I have two wires clamped together at four spots with the black clamps. Two spots have this blackish color on them and two do not.

I have run the engine several times since and seem to have a plug fouling issue that skips around to different cylinders at different times despite aggressive leaning and I'm wondering if clamping these wires together with the ordinary adel clamps have anything to do with it. Thanks in advance!
__________________
Mike Hillger
RV 7 FLYING SINCE 4/2015!
Garden City, Texas
First Flight https://www.youtube.com/watch?v=QqgxhWH3pqA
Dues Paid
Reply With Quote
  #2  
Old 02-16-2015, 10:30 PM
RV7A Flyer's Avatar
RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
Posts: 2,251
Default

I used the black Adel clamps in various places firewall forward, and they seemed to outgas and put similar dark stains on the engine mount, etc. No problems or issues, but it's just somewhat unsightly. I think the orange ones are better based on looking at a friend's -8 (he used only those and no discolorations).

That said, it does look like they're clamped awfully tight...
Reply With Quote
  #3  
Old 02-17-2015, 01:35 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,145
Default

Mike - I've got Adel clamps on my ignitions wires on my build, and they are stained like that also - and I haven't even had first engine start yet. It's a symptom of the Adel clamps apparently.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
Reply With Quote
  #4  
Old 02-17-2015, 02:43 PM
SmilingJack's Avatar
SmilingJack SmilingJack is offline
 
Join Date: Dec 2010
Location: Hilton Head Island
Posts: 1,089
Default

I think clamping those wires together is your problem.

Doing so could cause them to inductively couple or cause EMI.

Try to separate them.
__________________
John Mastro
RV-8
Reply With Quote
  #5  
Old 02-17-2015, 02:56 PM
Infidel's Avatar
Infidel Infidel is offline
 
Join Date: Sep 2011
Location: WV22
Posts: 849
Default

Quote:
Originally Posted by SmilingJack View Post
I think clamping those wires together is your problem.

Doing so could cause them to inductively couple or cause EMI.

Try to separate them.
I agree and I would sleeve each with some old fuel line and use a larger adel clamp, or adel clamp them individually.
__________________
RV-4 0320\D3G 160, Whirlwind 200GA 70".

Last edited by Infidel : 02-17-2015 at 02:56 PM. Reason: Ipad typo again
Reply With Quote
  #6  
Old 02-17-2015, 11:41 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
Default

Quote:
Originally Posted by airguy View Post
Mike - I've got Adel clamps on my ignitions wires on my build, and they are stained like that also - and I haven't even had first engine start yet. It's a symptom of the Adel clamps apparently.
+1

This staining is likely from the rubber, not arcing. Arching based deposits tend to be very narrow and take quite a bit of time to develop. Induction from one wire to the other won't cause plug fouling. Fouling, if related to ignition, would be from a weak spark or no spark. You are looking for resistance, not inductance to cause this. Inductance from one wire to the other doesn't steal from the source power, but can induce power where you don't want it; Also, not a cause of fouling. You want to check the resistance of all high voltage paths. If all are fouling, look at your mag.

Larry
Reply With Quote
  #7  
Old 02-18-2015, 07:10 AM
osxuser's Avatar
osxuser osxuser is offline
 
Join Date: Aug 2005
Location: Pasadena CA
Posts: 2,484
Default

Quote:
Originally Posted by SmilingJack View Post
I think clamping those wires together is your problem.

Doing so could cause them to inductively couple or cause EMI.

Try to separate them.
I don't think so, that is completely industry standard. They are both shielded, and there is no way they could arc over next to each other.
__________________
Stephen Samuelian, CFII, A&P IA, CTO
RV4 wing in Jig @ KPOC
RV7 emp built
Reply With Quote
  #8  
Old 02-19-2015, 05:28 AM
MikeyDale's Avatar
MikeyDale MikeyDale is offline
 
Join Date: Aug 2012
Location: Garden City Texas
Posts: 878
Default

Happy to say I believe I have solved the fouling issue. My idle mixture was very rich. I leaned it out to a point where I gained 30 rpm from full rich to leaned idle. I set the idle to 700 rpm. Cleaned the two plugs again and used a magnifying glass and found tiny clinkers that I wasn't seeing before. Then I ran the engine several times with no fouling. Thank goodness it wasn't the clamps or the mags.
__________________
Mike Hillger
RV 7 FLYING SINCE 4/2015!
Garden City, Texas
First Flight https://www.youtube.com/watch?v=QqgxhWH3pqA
Dues Paid
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 12:43 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.