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Brinky 
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 Topic: Allis B timing
Posted: 22 Apr 2025 at 11:42am |
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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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steve(ill)
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Posted: 22 Apr 2025 at 12:42pm |
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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.
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Like them all, but love the "B"s.
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Les Kerf
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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.
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Brinky
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Posted: 07 May 2025 at 11:58am |
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Thanks for all the advice, I have done the timing, managed to start her and take her for a run.
I now have a problem with the starter barely turning the engine over.
According to my charger the battery is 100% charged at about 6.5v, I have new 50mm cables. When the start button is pressed I have 4.5v at the starter is this too low?
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Les Kerf
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Posted: 07 May 2025 at 1:53pm |
 Brinky wrote:
... I have new 50mm cables. When the start button is pressed I have 4.5v at the starter is this too low? |
Did you perhaps mean 5mm cables? 4.5v is a bit low but 5mm cables are pretty small, 50mm is huge.
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ekjdm14
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Posted: 07 May 2025 at 2:02pm |
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Not sure why but over here we measure our cables by some kind of cross section or area of the strands added up do 50mm nominal does seem legit for 6v cables.
Why we can't go by wire gauge, I don't know. Works so much more intuitive for me at least.
4.5v is a little low but 6v starters never spin over like a 12v one anyway, as long as it can push through compression it should start well enough.
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Stuck Farmer
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Brinky
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Posted: 07 May 2025 at 2:02pm |
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50mm² , 345 amp
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steve(ill)
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Posted: 07 May 2025 at 4:12pm |
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50 mm divided by PIE ( 3.14) = 16 ( r**2)... so r = 4 or the diamter = 8 mm .... that is half way between gauge 1 and gauge 0 in the US... ( .311 inch dia).... most people would go a size or two BIGGER on a 6 v system.... If it starts OK, thats fine.. If it is COLD, WEAK BATTERY, WEAK MAG.. etc, etc... You "might" need larger cables..
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Like them all, but love the "B"s.
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mdm1
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Posted: 07 May 2025 at 6:08pm |
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Just did my 2 B's. Similar to what Les said. Bring the engine to TDC, compression stroke on #1 cylinder. I couldn't find any marks on my flywheels but the engine is TDC on compression when the set screw- bolt on the crank shaft pulley is at 12:00 O clock. Snap the mag on #1 and back it up to line up with the coupler. Should be horizontal. Mount it straight up. The next cylinder to fire will be #2. As far as the starter goes. Did you load test the battery? I just had one that wouldn't turn over ever though the starter would function on another battery. My battery was bad. Make sure all your connections are super clean especially the ground. Clean the area where the starter mounts to the engine. Welding wire size cables. I think you may be looking at a new battery. Good luck.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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Les Kerf
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Posted: 07 May 2025 at 7:48pm |
Brinky wrote:
50mm² , 345 amp |
Ah, thank you for the edification, I missed the little 'square' symbol  We do some things a bit differently on this side of the pond 
Those cables should be adequate; you could do a voltage drop test on them to verify.
Put one test lead of your voltmeter directly on the battery terminal and the other lead directly on the terminal stud at the starter. While cranking, read the voltage drop, it should be a tenth of a volt (0.10 Volt) or thereabouts. This will test the conductivity of the entire cable and the the connections.
Do the same on the ground cable, testing from the actual battery terminal to a good ground near the battery. The voltage drop needs to be very low on this one too.
Edited by Les Kerf - 07 May 2025 at 7:50pm
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Brinky
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Posted: Yesterday at 11:53am |
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I did a drop test today, fully charged battery measured 6.5 volts, when turning over on the starter stud it dropped to 0.5 volts, and on the ground it dropped to 4.5 volts
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Les Kerf
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Posted: Yesterday at 12:23pm |
Brinky wrote:
I did a drop test today, fully charged battery measured 6.5 volts, when turning over on the starter stud it dropped to 0.5 volts, and on the ground it dropped to 4.5 volts |
Perhaps I was not clear enough as to the purpose of the voltage drop test and how to perform it.
The intent is to test how much voltage is dropped (or lost) through the actual cable itself.
This is done by placing one probe on one end of the cable, and the other probe on the opposite end of the same cable. When no current is flowing, there will be no voltage drop at all. When the starter is cranking and current is flowing, there will be at least some voltage drop, but we want it to be very, very low.
If this is how you actually performed the test and found 0.5 Volts drop on one cable, that is cause for concern.
A drop to 4.5 Volts (losing a full 2 Volts) across the starter seems a bit much to me.
Did you do a drop test on both cables (one at a time)? If each cable is losing 0.5 Volts then you have too much resistance somewhere in the cable circuit.
The battery may also be weak as another member mentioned above.
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Brinky
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Posted: Yesterday at 12:42pm |
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Hi thanks for the swift reply. Yes I tested each cable individually as you explained the test on the starter stud is dropping to 0.5 volts, that’s a 6 volt drop.
I have the starter solenoid mounted in the tool box, so the cable goes from the battery to solenoid then from solenoid to the starter. It is a 6 volt solenoid used on early v8 fords.
Have had the battery on two different charges neither indicating a fault.
Thanks again
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Les Kerf
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Posted: 22 hours 24 minutes ago at 2:16pm |
Brinky wrote:
Hi thanks for the swift reply. Yes I tested each cable individually as you explained the test on the starter stud is dropping to 0.5 volts, that’s a 6 volt drop. |
Just to clarify so that I am understanding correctly; Are you measuring from the starter stud to ground? Or from the starter stud to the battery?
Brinky wrote:
I have the starter solenoid mounted in the tool box, so the cable goes from the battery to solenoid then from solenoid to the starter. It is a 6 volt solenoid used on early v8 fords. |
This adds another set of connections that could cause high resistance. A voltage drop test across the solenoid itself is in order.
Brinky wrote:
Have had the battery on two different charges neither indicating a fault. Thanks again
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Slow cranking can be caused by: Weak Battery Poor connectivity (high resistance anywhere in the cabling including the ground return path) Dragging Starter Excessive friction in the engine being cranked
Voltage drop tests are important in order to locate poor connectivity.
A clamp-on style ammeter is also very useful to determine actual current draw to pinpoint if the battery is weak or if the load on the starter is excessive.
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Brinky
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Posted: 22 hours 5 minutes ago at 2:35pm |
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From the starter stud to the positive terminal on the battery, its negative ground
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Les Kerf
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Posted: 21 hours 44 minutes ago at 2:56pm |
Brinky wrote:
From the starter stud to the positive terminal on the battery, its negative ground |
0.5 Volt drop from the starter stud through the solenoid and to the battery terminal is more than I like to see but also isn't horrifying.
If you are also losing 0.5 Volts on the ground cable then you are losing 1 full volt through the cables that isn't doing any good.
Even though the battery measures 6.5 volts doesn't mean that it can deliver full amps; a proper load test can be informative.
An amp draw test while cranking is the best test.
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Brinky
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Posted: 21 hours 18 minutes ago at 3:22pm |
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I have a 6 volt drop from the battery to starter stud . 6.5 volts to 0.5 volts
Edited by Brinky - 21 hours 17 minutes ago at 3:23pm
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steve(ill)
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Posted: 21 hours 13 minutes ago at 3:27pm |
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your cables are NEW ?.. I would wire brush the battery terminals until BRIGHT and SHINNY.. you can have an ozidefillm aa few thousndths thick and not really visible... also, wire brush the stater hole and starter case and the Ground bolt that attaches them.... make sure the SOLENOID itself is not causing a problem.
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Like them all, but love the "B"s.
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Les Kerf
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Posted: 20 hours 13 minutes ago at 4:27pm |
Brinky wrote:
I have a 6 volt drop from the battery to starter stud . 6.5 volts to 0.5 volts |
That indicates a MAJOR high resistance in that circuit  In fact, it is so major that it is difficult to imagine the starter being able to even budge the engine.
To clarify once again; with one meter lead on the battery terminal and the other meter lead on the starter stud, the meter is reading a 6 Volt drop while cranking?
It is important to take the reading only while cranking. Attempting to take this reading when not cranking will give erroneous readings.
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