Allis B timing

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   Just wanted to check what I read for the timing is correct.
When the magneto came back I turned it until it sparked on plug one. I then turned the engine over until I got compression on cylinder one and fire mark in the hole, I then advanced it to TDC and put magneto back on. Does that sound about right ? 

Edited by Brinky - 22 Apr 2025 at 12:14pm

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Brinky Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 30 Aug 2024 Location: Uk Points: 19	Post Options Post Reply Quote Brinky Report Post Thanks(0) Quote Reply Topic: Allis B timing Posted: 22 Apr 2025 at 11:42am
	Just wanted to check what I read for the timing is correct. When the magneto came back I turned it until it sparked on plug one. I then turned the engine over until I got compression on cylinder one and fire mark in the hole, I then advanced it to TDC and put magneto back on. Does that sound about right ? Edited by Brinky - 22 Apr 2025 at 12:14pm

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steve(ill) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 11 Sep 2009 Location: illinois Points: 85582	Post Options Post Reply Quote steve(ill) Report Post Thanks(0) Quote Reply Posted: 22 Apr 2025 at 12:42pm
	Normally you get the engine rotated so it is coming up on compression,, maybe the FIRE mark for #1..... then you rotate the MAG by hand and watch it fire on 2 -4 -3 .. then its ready for #1 NEXT... So you install the MAG and snug the bolts... as you rotate the motor to TDC you will see #1 SPARK... If its off a little, then loosen the mount bolts and rotate a few degrees one way or the other untill you fire at TDC.. You will need to rotate the engine 2 revolutions each time to RETEST for FIRE at #1 TDC.
	Like them all, but love the "B"s.

Les Kerf Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 08 May 2020 Location: Idaho Points: 1053	Post Options Post Reply Quote Les Kerf Report Post Thanks(0) Quote Reply Posted: 23 Apr 2025 at 2:05pm
	I just went through this with my B-125 engine. Get the engine rotated to TDC #1 compression (the magneto coupling should be horizontal), then rotate the magneto until #1 fires, then rotate the magneto slightly backwards enough to engage the impulse, then rotate it forward just enough to get the coupling horizontal, then install the magneto with the top of the magneto rotated toward the engine. Tighten the magneto bolts lightly so as to allow the magneto to still turn. Then CAREFULLY rotate the top of the magneto away from the engine until the impulse trips. If all went well this will be correct, then re-test and fine tune as needed. If you are able to rotate the engine backwards with the fan about a half-turn then you won't need to go forward the full two revolutions. I like to go forward a half-turn and, using a spark tester, check #2, then #4 and #3 in sequence and finally back to #1 just to verify that sparks are indeed happening when and where they should.