Magneto Impulse Questions
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=147796
Printed Date: 20 Oct 2025 at 7:24am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Magneto Impulse Questions
Posted By: JCSinPITTS,PA
Subject: Magneto Impulse Questions
Date Posted: 21 Feb 2018 at 5:32pm
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I have a question..... how do you KNOW you have a 30% lag impulse? and on AC - B do I time it idleing or at half throttle? and which mark do I time it to? It seems so simple yet when I review old posts there are a lot of differing opinions!
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Replies:
Posted By: Dakota Dave
Date Posted: 21 Feb 2018 at 5:44pm
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its a 30 Deg. lag on the impulse mag. the impulse only operates below 200 rpm. time it a idle. Time it to the F mark when running If its an airplane Mag it could be either 25 Deg. or 18 Deg. the deg lag on the mag doesn't make any difference on the engine when running. a distributor has advance weights so needs to be above 1/2 throttle to check timing with timing light.
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Posted By: Hubnut
Date Posted: 21 Feb 2018 at 5:59pm
I always thought the lag was built-in to the mag. If you time to the FIRE mark, everything should be just fine. I just did one this past weekend with a timing light. Boy, you think you can hear when it's timed properly. I timed it by ear, then put the light on it. I couldn't even see the FIRE mark! I got it just right with the light. Never trust your ears--or at least mine.
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1940 B "Lucy"
1941 B w/ Woods L59 "Flavia"
1942 B w/ finish mower "Dick"
1941 C w/ 3-point "Maggie"
1947 C SFW w/ L306 "Trixie"
1972 314H
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Posted By: CTuckerNWIL
Date Posted: 22 Feb 2018 at 11:40am
Static timing is done with the C or TDC mark. With the engine running at proper rpm, the fire mark is used with a light.
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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF
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Posted By: HoughMade
Date Posted: 22 Feb 2018 at 11:43am
Static time to "Center", get it running, then at about 1/2 throttle or above, tune by ear or with a timing light to "Fire".
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1951 B
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