Finally Started Reassembly
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Joined: Mar 2010
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From: Poolville
I copy/paste this from this link..
https://www.hdforums.com/forum/engin...explained.html
"The VOES is a motorcycle part described as a vacuum ignition retard device. That is, under low vacuum conditions the switch is open and has no effect on ignition timing. Under high vacuum, the switch closes and advances ignition timing. Essentially, the VOES is like the vacuum advance in older type automotive distributors.
For racing applications or supercharged, turbo-charged or bikes using Nitrous Oxide, we do not recommend using a VOES. This is due to the possibility of a sudden timing change causing a backfire which can be a bad thing under these conditions! "
My response is this: "I don't like them"
On a light tip in on the throttle the switch will will remain closed fully advancing the ignition timing causing the possibility of pre-ignition, this occurs at 1500 rpm and above. Not something I want on a high compression motor pe-igniton could lead to detonation which is real bad for any motor. Under a hard throttle where the vacuum drops below 5" the switch opens which will retard the timing 10 degrees to a total of 25* advance. Do you really want only 25* advance at full throttle and at 4000 rpm. I hardly think so at that point cause now your limiting your timing advance and robbing the motor of power.
One major change I noticed is that I no longer get a ignition chug, almost a pinging or rattling like to much timing under the load of starting off from a stop. The motor now accelerates very nicely from a stop, no chug.
Once my motor is broke in properly I will be going to a timing advance curve that I have specifically set up for my build and will never have full advance at a tip in @ 2200 rpm but will still have 31*@3100 rpm and 38@3800 rpm etc. It will be aggressively matched to the proper rpm without having any detonation but will be set for optimal performance.
In the old days I did the same with the ignition on my SBC's Using Accel distributors without vacuum advance and setting up the centrifugal advance by changing spring tension to determine the ignition curve and when full advance would come in..
I hope this explains it for you but it is all a personal preference.....
Actually this link probably explains it best.
http://www.dynaonline.com/skins/down...ct/D2Ki-1P.pdf
https://www.hdforums.com/forum/engin...explained.html
"The VOES is a motorcycle part described as a vacuum ignition retard device. That is, under low vacuum conditions the switch is open and has no effect on ignition timing. Under high vacuum, the switch closes and advances ignition timing. Essentially, the VOES is like the vacuum advance in older type automotive distributors.
For racing applications or supercharged, turbo-charged or bikes using Nitrous Oxide, we do not recommend using a VOES. This is due to the possibility of a sudden timing change causing a backfire which can be a bad thing under these conditions! "
My response is this: "I don't like them"
On a light tip in on the throttle the switch will will remain closed fully advancing the ignition timing causing the possibility of pre-ignition, this occurs at 1500 rpm and above. Not something I want on a high compression motor pe-igniton could lead to detonation which is real bad for any motor. Under a hard throttle where the vacuum drops below 5" the switch opens which will retard the timing 10 degrees to a total of 25* advance. Do you really want only 25* advance at full throttle and at 4000 rpm. I hardly think so at that point cause now your limiting your timing advance and robbing the motor of power.
One major change I noticed is that I no longer get a ignition chug, almost a pinging or rattling like to much timing under the load of starting off from a stop. The motor now accelerates very nicely from a stop, no chug.
Once my motor is broke in properly I will be going to a timing advance curve that I have specifically set up for my build and will never have full advance at a tip in @ 2200 rpm but will still have 31*@3100 rpm and 38@3800 rpm etc. It will be aggressively matched to the proper rpm without having any detonation but will be set for optimal performance.
In the old days I did the same with the ignition on my SBC's Using Accel distributors without vacuum advance and setting up the centrifugal advance by changing spring tension to determine the ignition curve and when full advance would come in..
I hope this explains it for you but it is all a personal preference.....
Actually this link probably explains it best.
http://www.dynaonline.com/skins/down...ct/D2Ki-1P.pdf
Last edited by 98hotrodfatboy; Mar 2, 2016 at 08:00 PM.
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