Notices
Engine Conversions Discuss all aspects of engine conversions in this forum

CH Ignition

Old 06-23-2009, 10:26 PM
  #1  
Kimhoff
Thread Starter
My Feedback: (22)
 
Join Date: Sep 2003
Location: Jefferson, MO
Posts: 655
Likes: 0
Received 0 Likes on 0 Posts
Default CH Ignition

I bought a CH ignition that has the timing advance built in. CH told me to set the static ignition at 28-32 degrees before TDC? If this is correct how can the igniton retard to anythig less than the seting of 28-32 before TDC. Shouldn't the static timing be set at 4-8 degrees? I can see see how the timing could be advaced from this point based on the engine RPM that could be measured by the time between pulese.

Can anyone help me with this?

Thanks

Old 06-23-2009, 10:38 PM
  #2  
RC Extreme power
Senior Member
My Feedback: (24)
 
RC Extreme power's Avatar
 
Join Date: Dec 2001
Location: AUBURN, GA
Posts: 1,323
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

Why question them, They have been doing ignitions for longer than we have been using gas engines for model planes, It works set at 28 deg.

http://www.rcuniverse.com/forum/m_8868990/tm.htm

Milton
Old 06-23-2009, 10:44 PM
  #3  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 1 Like on 1 Post
Default RE: CH Ignition

The timing doesn't advance. It retards

A fast flip past the sensor will retard it about 16 degrees and it doesn't get to full advance intil up around 4500

If you think about it electronically, it could only retard
Old 06-24-2009, 12:32 AM
  #4  
av8tor1977
My Feedback: (6)
 
av8tor1977's Avatar
 
Join Date: May 2003
Location: Tucson, AZ
Posts: 7,213
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

Yes, "auto advance" is a misnomer; it should be "auto retard". There is a computer chip in the ignition that senses the speed (or rather time) that the magnet is under the sensor. At very slow rpms, like when you slowly turn it over by hand, the timing is advanced. That way you can set the timing at your desired max advance. When the engine is turning a few hundred rpms, the ignition retards itself for starting and low speed running, then starts advancing as the rpms rise up to where you initially set it when the rpms reach 4000.

AV8TOR
Old 06-24-2009, 12:40 AM
  #5  
tkg
My Feedback: (1)
 
Join Date: Jan 2002
Location: Riverton, WY
Posts: 3,114
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

What he said........
Old 06-24-2009, 07:54 AM
  #6  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

also what my strobe tests showed.
Old 06-24-2009, 02:39 PM
  #7  
captinjohn
 
Join Date: Jan 2002
Location: Hesperia Michigan, MI
Posts: 12,945
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition


[quote]ORIGINAL: av8tor1977
I will say the description how it works is very good. But any ignition tha advances the timing with the RPM increasing...is a auto advance ignition. Capt,n
Old 06-24-2009, 08:19 PM
  #8  
av8tor1977
My Feedback: (6)
 
av8tor1977's Avatar
 
Join Date: May 2003
Location: Tucson, AZ
Posts: 7,213
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

You do love to argue Captain John....

AV8TOR
Old 06-25-2009, 12:35 AM
  #9  
tkg
My Feedback: (1)
 
Join Date: Jan 2002
Location: Riverton, WY
Posts: 3,114
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

[quote]ORIGINAL: captinjohn


ORIGINAL: av8tor1977
I will say the description how it works is very good. But any ignition that advances the timing with the RPM increasing...is a auto advance ignition. Capt,n
No that is incorrect. An ignition that is an advancer STARTS with the timing around 4-5 deg BTDC. An ignition that is a retarder starts around 30 Deg BTDC and retards the timing at low RPM. As the rpm increases it returns to its starting point. It does not advance, it retards less.
Why don't we just call it Computer Controlled Timing.
Old 06-25-2009, 12:59 AM
  #10  
av8tor1977
My Feedback: (6)
 
av8tor1977's Avatar
 
Join Date: May 2003
Location: Tucson, AZ
Posts: 7,213
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

Thanks Terry; I didn't want to "get started" and get into a huge unnecessary discussion about it. Remember the big "Top Dead Center" debate some time ago?

AV8TOR
Old 06-25-2009, 07:48 AM
  #11  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition


[quote]ORIGINAL: tkg

ORIGINAL: captinjohn


ORIGINAL: av8tor1977
I will say the description how it works is very good. But any ignition that advances the timing with the RPM increasing...is a auto advance ignition. Capt,n
No that is incorrect. An ignition that is an advancer STARTS with the timing around 4-5 deg BTDC. An ignition that is a retarder starts around 30 Deg BTDC and retards the timing at low RPM. As the rpm increases it returns to its starting point. It does not advance, it retards less.
Why don't we just call it Computer Controlled Timing.
Terry,
It is good to know if the ignition is an advancer or a retarder if you consider how to set the timing.
Advancers need to have the timing set at between TDC and 6° BTDC
retarders must have a setting of 20° - 35° BTDC, depending on engine make and application.

Some advancers, like the VLACH and Falcon are/were in fact super retarders. Because the pickup signal came too late to fire the same cycle, the signal time was stored and used to fire the next cycle! If I am informed well, they used the mean of the last 10 cycles to do that. When starting, these were fixed timing ignitions, switching to super retarding when the engine was running.
Old 06-25-2009, 09:33 AM
  #12  
captinjohn
 
Join Date: Jan 2002
Location: Hesperia Michigan, MI
Posts: 12,945
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition

Oh...we had fun with that advance-retard thing...yup tis great to know this stuff. That is why it is a good idea to read as much as you can before you try something new!!! I sometimes reply to postings here & there just to get that extra data placed for new experimenters!!!! Best Regards capt,n
Old 06-25-2009, 01:22 PM
  #13  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 0 Likes on 0 Posts
Default RE: CH Ignition



Of course ALL electronicaly advanced ignition advance the firing as rpm rise. 'tis just the way how they do it.

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.