Chris Haynes
Well-known member
Does anybody know what the amount of auto advance is in a Wico JEM magneto?
Wico JEM Magneto questions
- Thread starter Chris Haynes
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Crazydaddyo
Senior Member
There is no auto advance in the Wico Magnetos.
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Chris Haynes
Well-known member
There is in the JEM models. I just don't know how much.The Wico JEM 1509 models were made specifically for Fords.
Crazydaddyo
Senior Member
No advance. There is a retard feature called an impulse drive. It retards the timming for starting. Once the engine reaches idle speed,the timming is fixed.
Chris Haynes
Well-known member
If it retards to start then advances that is what I mean. I am just trying to find out how much the retard/advance is?
Crazydaddyo
Senior Member
If you are asking how much advance to account for to set the initial timing, then the answer is I don't know. But you can't set the timing on a mag that way. I've had the best results by setting the timing while the engine is running @ 1200 rpm. Because the timing is fixed, you have to set the timing where you want to run it. I set it @ 25 - 28 deg. advance @ 1200 rpm. Drive the car around and see if there is any detonation (ping or knock) then adjust up or down accordingly. If it pings, back down the timing a little. If no ping, bump the timing up a little. Once you are happy, put your timing light on it to see where it is and write it down.
just plain bill
Senior Member
Specific for Ford industrial engines usually farm equipment.
If the mag has the impulse it will have what is called a lag angle instead of calling it an advance. usually 9 to 12 degrees. the impulse mechanism should kick out at from 150 rpm's to plus 200 rpm's. Initial timing is set at TDC turn mag shaft until impulse snaps at number 1 post on mag cap then install and align number 1 wire to number 1 cylinder. Then adjust as CDO said usually just so it doesn't kick back at cranking speed.
The magneto runs at what ever you set it at but the rotor lags behind at cranking speeds at what ever the lag angle built into the magneto so you could say it retards the spark that amount but again , it is called the "lag angle".
I remember when some engines had a manual impulse that was a small lever on the magneto that you set before cranking because they had no starter and had to be hand cranked. Been there, done that, but didn't get a T shirt
If the mag has the impulse it will have what is called a lag angle instead of calling it an advance. usually 9 to 12 degrees. the impulse mechanism should kick out at from 150 rpm's to plus 200 rpm's. Initial timing is set at TDC turn mag shaft until impulse snaps at number 1 post on mag cap then install and align number 1 wire to number 1 cylinder. Then adjust as CDO said usually just so it doesn't kick back at cranking speed.
The magneto runs at what ever you set it at but the rotor lags behind at cranking speeds at what ever the lag angle built into the magneto so you could say it retards the spark that amount but again , it is called the "lag angle".
I remember when some engines had a manual impulse that was a small lever on the magneto that you set before cranking because they had no starter and had to be hand cranked. Been there, done that, but didn't get a T shirt
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Chris Haynes
Well-known member
Thanks to you all for sharing.
johnneilson
Well-known member
Not hijack the thread, I have been told that Porsche distributors or mags can be adapted to Model A/B motors.
Has anyone here done this?
I have an old one, it indicates 0° 1750 - 12 1/2° 1900
This would be nice as long as the 1700-1900 is crank speed and not mag speed.
My side drive Bendix has lag, I can just imagine trying to hand prop an old airplane without it.
John
Has anyone here done this?
I have an old one, it indicates 0° 1750 - 12 1/2° 1900
This would be nice as long as the 1700-1900 is crank speed and not mag speed.
My side drive Bendix has lag, I can just imagine trying to hand prop an old airplane without it.
John
Crazydaddyo
Senior Member
John,
I have seen those Mags too. The ones I've seen are Vertex mags. I have talked to some one at Don Ziggs about centrifugal advance on vertex mags and they say yes, it is possible. I haven't done it yet, but I do have a 4 cyl. Vertex mag that I would like to send to them and have it set up for the street.
If I recall correctly, the VW / Porsche mag run the opposite way then a Model A / B..
I have seen those Mags too. The ones I've seen are Vertex mags. I have talked to some one at Don Ziggs about centrifugal advance on vertex mags and they say yes, it is possible. I haven't done it yet, but I do have a 4 cyl. Vertex mag that I would like to send to them and have it set up for the street.
If I recall correctly, the VW / Porsche mag run the opposite way then a Model A / B..
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