John T, clooney a little thunder in the hills

Theres two different timing settings on that mag: (1) The initial start timing (rotating mag CCW to advance or CW to retard) and (2) The run time advance (lag angle) (set by rear stop ring location)

(1) INITIAL START TIMING: When you loosen the mags mount bolts, the Initial Start Timing is set by rotating the Mag CCW to advance or CW to retard. You set it such that it snaps to fire the Left Plug just as the Left Hand Impulse timing mark on the Flywheel is at 3 O Clock in line with a flat mark on the tractors side (when Left piston is at TDC IFFFFF FFFF flywheel and crank and cam and governor are ALL in time). If it fires too soon before that, the flywheel can kick back but if too far after, she dont start as well. You can get it initially roughed in by first settign the mag as far retarted (CW) as possible, slowlyyyyy yy bring the flywheels LHI to 3 o clock at the flat mark and stop, and then slowlyyyyy yy rotate the mag advance CCW till it snaps and stop. Then fine tune it in by rotating the flywheel and listenign for the snap and fine tune/time the mag so the snap occurs just as LHI passes 3 O Clock.

(2) RUN TIME ADVANCE (Lag Angle):

The amount of spark advance when shes runing (over 250 RPM when spring wind n trip disabled) is determined by the mags rear coupler stop adjustment. Most are set where if the index mark is straight up center, that represents 12 1/2 degrees of run time advance and each mark represents another 5 degrees. Therefore, if you set it 2 1/2 marks to the left, the run time advance is 12 1/2 + 5 + 5 + 2 1/2 = 25 degrees of advance. HOWEVER, thats not exact, it also depends on your coupler (I think Duane Larson has data on coupler numbers and advance) and the amount of wear it has. The way to tell when shes firing at over 250 RPM (amount of run time advance) is to measure the flywheels outer circumference, divide that by 360 degrees to get inch units per degree, then mark the flywheel like at 15, 20, 25, 30 etc BTDC and use a timing light to see wheres shes actually firing.

NOW TO YOUR QUESTIONS: Ifffff ff you set the mags initial start timing (rotate mag CCW or CW) so it snaps to fire the left plug just as the Flywheels LHI mark passes by the 3 0 Clock flat mark, that ought to be okay. HOWEVERRRRR RR If the flywheel or crank to cam or (most often the problem) the governor are not ALLLLL L in time, that can result in you not being able to rotate the mag to where it fires at TDC or it has to be way at one extreme end of the adjustment.

CORRECT TIMING: If the flywheel is on the right crank splines and crank and cam are in time PLUS GOVERNOR GEAR IS IN TIME WITH CAM, when the Flywheels LHI is at 3 O Clock, Left Pistons at TDC, the open female drive cog in the governor shafts end (where mags male drive fits) should be flat horizontal fore and aft. If nottttt tt but all else is in time, the governors drive gear could be off a few teeth whereby the mags CW/CCW start timing setings need to be corrcted (if possible) so the mag snaps at TDC.

Sooooo o, you may wanna check the governor gears timing (drive is horizontal fore n aft)before you proceed.

If the mag isnt snapping or you had to mess with the coupler to make it do so, one problem is the trip dogs are stickign or dirty or corroded and are NOT coming out to catch so the spring winds up n trips. I usually clean them out with air and WD 40 etc., so they are clean n free and come out to catch and wind the spring as you rotate the coupler CCW facign it.

TIMIGN SUMMARY: Then the run time advance is set initially to 2 1/2 marks to the left, then the mag is installed (into a correct timed governor) and the initial start timing is set so the mag snaps just as the LHI passes 3 O Clock, then a timing light can be used to verify actual run time advance.

Finally that spitting you describe could be a stickign valve or its lash isnt set proper or the timings way off (set per the above), or other problems.

To be safe, inspect the point gap for 0.015 and replace them if carboned up or burned or pitted or gray oxide coated. Use wire core NOT carbon core wires, inspect the lil outer cap for good contact with the rotor arm, inspect the inner cap and where the contactor makes good solid contact with the coils side output button/terminal, try fresh plugs (maybe the hotter side wire type like Autoliyte 3077 or equivalent), post back your findings, results and any questions, and take 2 aspirins and call me Monday at the office lol.

Let us know, Good Luck n God Bless

John T jmn50@msn.com

You ask…
Quote: “When i installed it had to move the timing mark way to the left to get it to trip right when timing. Is this useable this way or should i change it out” >>>

_As long as the impulse stop ring [with back of mag facing you] is somewhere around 2-1/2 to 3-1/2 hash marks left of the center mark you should be fine [see below for details]..

Quote: “Second i ran it for 30 seconds then shut it off ,then tried to start it with the petcocks shut and it snezzed out the carb, then I opened the petcocks and tried again and it did it again and I got nerves and quit . what should I try next, thanks” >>>

_Probably the place to start is to set the impulse stop ring on the mag about 3-1/2 marks to the left of the center [straight up] mark,,[with the rear of the mag facing you] that should give you around 30° running timing [give or take a little].. The straight up mark should be about 12.5° & each mark left of center gives you about 5° more running advance.

~Regardless of where you set that impulse stop ring it shouldn’t effect the starting timing as the starting timing is based on where you originally installed & timed the mag to the flywheel [L/H Impulse] writing VS case mark..

~You need to install & adjust that mag so the mag snaps just as the [L/H Impulse] writing on the flywheel lines up with the case mark [that case mark is at 3 o’clock directly behind the flywheel & at the same height as the center of the crankshaft]..

~If the mag is now snapping just as the L/H Impulse marks line up with the case mark & it still pops back through the carb as you try to start it try adding another mag base gasket,, sometimes those mags sit a little tight to the governor drive flange & that can impede the mag’s ability to snap at the correct time..

~If your starting timing isn’t per the above then set it to the above..

~If your mag starting timing is set per the above & it still pops through the carb when cranking make sure the mag cap isn’t incorrect or that it doesn’t have any cracks or carbon traces in it.. Also verify that the spark rotor has the correct spaced tangs on it that allow the rotor to line up with the cap’s internal terminals as the points open for each cylinder..

~Other than that make sure the points gap is set to .015” on the high part of the points cam & that the mag shaft bushings at not loose & that the mag shaft is tight..

~If you had the impulse cup off [or the mag is un-tried before] make sure the impulse cup isn’t tight or binding on the lower nut & that the little swinging impulse catch arms move freely on their pins..

~Here’s the bottom line—If the mag is snapping as the L/H impulse mark on the flywheel lines up with the case mark while cranking, & the mag has the correct cap & spark rotor your problem isn’t timing..

~The top of the mag is rotated towards the front of the tractor to retard the spark timing & the top of the mag is rotated towards the rear to advance the spark timing..

~It’s possible you have a poor starting spark so you might want to check that.. To do that--Take an old spark plug [it doesn’t have to be for your tractor], then open that plug gap to 3/16” [use a 3/16” drill bit for a gap gage], then install that plug in one plug wire at a time & lay it on the engine block.. Then crank the engine & watch that plug.. You need to see a bluish colored spark jump that 3/16” gap every other time the mag snaps.. If the spark is yellowish, wimpy, or intermittent then you probably need mag work.. Try the test again using a paper clip in the mag wire towers & bend the paper clip to within 3/16” of the metal mag case.. If the spark is still poor the mag needs work.. If the spark is better with the paper clip test you probably need plug wires.. If you pass the above spark test that says the coil is making good contact, the condenser is working good, the points are functioning & that the mag has enough oomph to easily start that tractor..

~A little additional info—It probably wouldn’t hurt to try new spark plugs as partially fouled spark plugs can cause all kinds of starting & popping at starting problems.. It also wouldn’t hurt to check your plug wires, they must be metallic core [not carbon core automotive TVRS wires]. Carbon center plug wires are the kiss of death for a mag equipped tractor.. .

~Other that that make sure the choke is operational & fully closes & that your valves are adjusted correctly & not sticking or leaking..

Any questions just post back or E-Mail..

JDClooney@aol.com

Quote: “the mag looking at the rear from the 12:00 o'clock I forgot to tell you that sorry. I had to move all the way to the left to get it to be in adjustment on the governor when timing” >>>

_If you had to move that stop ring that far to get it to time out that says either the mag impulse is not correct or the engine governor to flywheel/crankshaft position isn’t set correctly..

~First--You should probably pull the mag back off,, then remove the L/H spark plug & stick a wire or pencil in the L/H plug hole,, then roll the engine flywheel until the L/H piston hits the wire,, then roll the flywheel in both directions until you are sure the piston is exactly at TDC.. At that time the L/H Impulse writing on the flywheel should be lined up with the case mark [at 3 o’clock directly behind the flywheel].. If it isn’t then the flywheel is not installed correctly [that flywheel MUST be on correctly to both check & time that tractor]]

~Once you are certain the flywheel is on correctly then just rotate the flywheel until the flywheel slot is running exactly fore & aft [parallel with the ground],, at that time the slot in the governor’s magneto drive flange must be running the same direction & at the same angle.. As long as the slot in the flywheel & the slot in the mag drive flange run exactly the same direction at all times your governor mag drive flange is timed correctly.. If that proves out then your problem is in the mag.. If the governor’s mag drive slot doesn’t match the flywheel’s slot then carefully remove the governor’s L/H cover & work the governor driven gear out, up, & re-position it so the governor to crankshaft gear is timed correctly, then reinstall the cover using the same gaskets..

~Once the mag drive flange is positioned correctly then you can re-set the magneto’s stop ring to 2-1/2 to 3-1/2 marks left of the center mark & get it t time out correctly [2-1/2 marks left of center = 25° & 3-1/2 marks left of center = 30°]..

You also say…

Quote: “The thump was the pinging from the compression and that I should get better fuel. I have an electric kit and coil to put on it but don’t have a distributor yet. I just want it to run, I’m getting excited but don’t want to rush it.” >>>

_That thump could be normal, or could be due to the magneto running timing being way too far advanced due to that magneto stop ring being moved too far to the left [the farther left that stop ring is turned the more running timing you are running..

~If you are going to use a distributor it sounds like you have a battery in it.. If so you can use a timing light to check the ruining timing.. To do that—
First make darn sure the flywheel is on the crankshaft correctly [see above for how to] ..
Then, use a tape measure & measure the circumference of the flywheel [not the ring gear teeth though]..
Then, divide that number by 360 [that will give you inches per degree]..
Then multiply the inches per degree by the running timing you want to run [probably 25° or 30 °,, that will give you the distance from the L/H impulse mark you want to mark the flywheel at [probably somewhere in the 4” to 5” range]..
Then, turn the flywheel so the L/H impulse mark lines up with case mark..
Then, measure UP from the L/H impulse mark on the flywheel the amount you came up with in the above [probably around 4”-5”] & put a paint mark.. Then, run the tractor at fast idle & put your timing light on the L/H plug wire..
Then check the running timing against that paint mark you made..

~Using the above you can set the base [starting timing] then also check the running timing.. If you are running much over 30° advance it will thump & knock pretty good under a load..

~If you don’t want to figure the timing yourself,, just E-Mail me the circumference [distance around] of your flywheel & tell me the amount of spark advance you want to run & I will E-Mail the measurement back to you..

Any more questions just post back here or E-Mail me..

JDClooney@aol.com

As far as pre ignition spark knock or pinging, it usually takes a fairly high compression (or maybe a hot spot) to cause that, and unless you have stroked n bored or dome topped pistons to significantly raise it from the relative low stock compression, thats usually not much of a problem with 87 octane gas. If the timign is wayyyyy y fast, however, such that it fires way before TDC, that can cause your problem. Again, you better check the governor gear to cam gear timing to insure the governors female slot is flat horizontal fore n aft when the flywheels LHI is at 3 O Clock and left pistins at TDC.

Best Wishes

John T