Mag impulse lag

Thanks

Checked fuel flow and found very little. OK, good, problem solved. Nope, plenty of fuel flow now and runs just like it did before.

Checked aircleaner restriction - none.

Checked points. They were about .025". Closed em up to .015". No change in the way it runs.

Set timing with the light and impulse where it started in the right direction.

I have adjusted on the carb till I wore out the screws. 1 turn out on the load makes a little smoke pullin hard and 1.25 turns on the idle makes a little smoke at slow idle.

Tractor ran about like it did before I started messing with it. I cut a second gov. spring to about 75% of its original length and placed it behind the new gov. spring. Tractor runs much smoother now. Still hunts around at idle, but runs smooth from half throttle up. Half my problem is solved now. I guess the other half lies in the gov. somewhere I can either tear into it and mess up my paint, or learn to live with an idle that isn't as nice as I would like. I would assume if I took the gov apart and replaced or redid everything loose it "should" get better?

Thanks for the help,
John

John

~There is no way to know exactly where your lag [starting] timing is now as the center mark is usually 12.5�, but that could be different depending on the impulse drive cup used.
~If you just marked the mag & pulled it out & didn't re-time it to SNAP at the L/H impulse to case mark line up, the running timing didn't change anyhow. That stop ring ONLY controls the under 250 RPM timing unless the mag is re-timed to the engine using the [static] mag snap at L/H impulse mark to trans case mark line up.
If you actually moved the mag orientation to the governor [turned the case from where it was] & the engine doesn't run any different, your timing probably ISN'T your power & poor running problem.
~You might just mark the mag case to governor, then take the tractor out & drive it, if a few moves of the mag case in relation to the governor doesn't make it run better you are looking in the wrong place for your problem anyhow.
~You might have a carb problem, or a fuel flow problem, or other internal engine problem. ~Try running it with the entire air cleaner disconnected to see if that helps, then try running with the choke about � way back on to see if that helps, try running it with the load needle if different positions from about 1 turn out to about 3 turns out. If that makes a difference you are at least closing in on the problem. Do a fuel flow test on it�Open the carb drain cock & see if you have a pencil sized stream of fuel flowing for AT LEAST 30 seconds [if not you have probably found your problem].
~Usually if the timing is too far advanced you will get spark knock, starting kickbacks, poor low RPM power but a crisp idle.. If the timing is too late [retarded] you will get low power, poor throttle response, engine overheating, lots of exhaust noise out of the muffler, a labored idle & just a general sluggish running engine.
~Any questions just post back or E-Mail.
[email protected]

Your question only involved timing the lag angle so thats all I answered below, and still the 2 1/2 marks to left (CCW) of center, which is 25 BTDC if the start timing is near TDC per my post, ought to get you in the ball park at least. Straight up is only 12 1/2 advance you know and thats probably tooooo o slowwwww ww, while full to left is likely too fast. Try 2 1/2 to left.

HOWEVER, maybe we should look into a few other problems like fuel related or valves etc., so I have to ask a few questions to better diagnose a potential problem now besides timing. I will talk about fuel or carb restrictions first in case shes starvign for fuel IS IT????

1) Have you adjusted the valves lately??? Know where they are set at now???

2) Have you adjusted the carbs top load and idle needles and does that help??? Maybe they need to be richer (out more).

3) Does a bit of choking help her smoth out????

IF SO she may be runnign lean due to a fuel flow restriction or a carb problem, so do these tests and it will help us diagnose a fuel or carb problem maybe.

4) With the gas on if you open the carb bowls lower drain cock/plug, does a soild continuous stream of gas approx 1/16 inch in diameter flow out a couple minutes or so????? If not, theres insufficient gas keeping the bowl full and that can cause a lean condition. Such may be due to a restricted or clogged needle valve n seat or a flow restriction in the tank bottom or sediment bowl or side inlet carb fuel strainer.

5) If she dont pass that flow test, remove the line from the carbs inlet and see if a solid stream flows out the line the size of its inside diameter???

6) If not, remove the glass sediment bowl and see if gas flows good out the lil top holes which fills the glass bowl???

7) If not, there may be a restriction in the tanks bottom or the inlet pipe or any mesh screen etc.

8) If it has good flow through the line but the bottom bowl drain test I described above fails, the clog may be in the needle valve n seat or the side inlet strainer.

9) First, remove the lil side plug in the strainer and see if you can clean and carb cleaner it all out and get some cleaner down into the needle valve n seat and see if that helps??? If not, you can remove the strainers top nut and cap and try to clean out the strainer.

10) If the gas flow is good through the sediment bowl and line and strainer, but she still fails my bottom flow test, the needle valve n seat may be clogegd which you can get to and clean by removing the bowl. When in there, check the float and its level setting.

11) You might also check that the air cleaners lower bowl is clean and water free and theres no inlet air restrictions and the gas is clean and fresh and water free.

11) If the flow to the bowl is good (bottom flow tests passes) and she startves for fuel or needs choke to run better, the carbs main center vertical brass nozzle may be clogged, especially some of its lil teeny side holes. You may have to drill and tap its center to use a screw and nuts n washers to pull it out (DO NOT BEND OR PRY ITS TOP) and once out clean and polish and clean all its lil side holes.

12) Have you checked for vacuum leaks (leans out fuel mixture)??? Do that by spraying WD40 or crab claner or an unlit propane torch around the base of manifold and carb gaskets and throttle shaft bushings etc to see if that smooths thigns out. Thats usually more of an idle problem, however. If youre just having idle problems, post back and I will tell you how to troubleshoot that.

13) Other than timing, I havent addressed the quality of your spark, do BOTH plugs produce a good visible blue spark and NOT a faint thin wimpy yellow one??? If so, post back and I will guide you through more igntion troubleshooting.

Thas enough to keep you busy lol, s0 let us know what the timign was,,,,, ,, and how the spark looks,,,,, , and if shes leaning out or needs choke to smooth out,,,,, and if carb adjustments help. Post back or e mail [email protected] or call 812-824-4608 with any more questions and I will try my best to help you John.

God Bless Ya

John T Nordhoff in Indiana

~Probably before using any setting instructions you should define what your tractor wants for a lag angle. Remember with a mag you have a single advance event �only� & not a graduated timing curve like a distributor has. With that X mag you get 100% full advance at slightly over 250 RPM's, so if 30� is good at wide open throttle & full working RPM it MUST also work at 600 RPM while the tractor is lugging.

~With the above in mind mark the mag base to governor housing [so you can put the mag back in it's original position], then take the tractor out & run it like you are going to use it. Run it at part throttle under load, full throttle under load & anywhere you want in between�. Once you establish a base line,,, loosen the mag retaining bolts & rotate the top of the mag to the rear about 1/4" & try your test again. Move the mag a few times to find the optimum place the tractor operates the best [for you]....Remember moving the top of the mag to the rear advances the spark.

~Once you have established the best place for your running timing [at least then you will know what you desire, though it might be more than you should run ] then you can re-set your lag angle to provide the correct starting timing.

�..To re-set or check your lag angle [using the on tractor timing light method]�..

~First thing to do is verify the flywheel is on correctly & the L/H impulse mark lines up with the case mark at EXACTLY TDC. To do that, remove the L/H spark plug, then insert a pencil {or wire} in the L/H plug hole as you turn the flywheel to TDC L/H piston. Feel for the piston to just touch the pencil. Once you feel it touch the pencil, mark the flywheel at the case mark.. Now turn the flywheel about 360� in the opposite direction & feel for the piston to touch the pencil again [hold the pencil the same way for both flywheel directions], then mark the flywheel again as the piston just touches the pencil�.. Exactly � way between those two marks you made is the TRUE TDC. [put a mark there & label it TDC!]

~Once you have established the actual TDC on your tractor you can then use a timing light to set your timing & check your mag lag angle.

~To do that,,,, first measure the outer circumference of the flywheel [not the ring gear teeth],,,then divide that number by 360 [there�s 360� in a circle],,that will give you inches per degree [will be a fraction less than an inch],,,then take your desired running timing [in your case you specified 30�] & multiply that by the fraction you came up with in above [probably will end up with something like 'example' 2.567� or 3.145�],,,then turn the flywheel so the mark you made for exactly TDC is lined up with the case mark,,, then measure UP from that TDC mark you made the amount figured in the above [example 3.145� or �3-1/8� up] then put another mark on the flywheel at that location [use a different color if possible]. [that is your running timing mark]

~Now all you have to do is hook a timing light to the L/H plug wire, power the timing light [use a remote12 volt battery, or battery charger if your B doesn�t have a 12 volt battery] & point & shoot. You can then see where your timing is in relation to that 30� mark. You can also figure a mark for 20�,25�, 30� on the flywheel if you want but it starts to get pretty confusing with too many marks.

~Once the desired RUNNING timing is set you can then shut the tractor down & slowly turn the flywheel in the running direction & listen for the mag to snap. If it snaps close to L/H impulse mark lining up with the case mark you are good to go�If it snaps early or late you can determine how much early or late by placing a mark on the flywheel at the point that it snaps at then using the above [INCHES PER DEGREE to figure out how far you are off.

~Then all you have to do is MARK THE MAG TO GOVERNOR so you can put it back correctly], then pull the mag, then turn it so the impulse is facing you, then loosen the impulse STOP RING retaining screws & rotate the stop ring to adjust for the amount the lag angle [starting timing] is off. Each mark is 5� with the center [straight up] mark being 12-1/2�. For example, If you determined the starting timing was 5� too early just loosen the impulse stop ring screws & rotate the stop ring one mark away from the center mark [that will change the lag angle 5�].

~If you don�t want to do the math, just post [or E-Mail] your flywheel circumference & the amount of timing you want to run & I will figure the inches you need to measure up from your TDC mark to use a timing light & send it to you..

~You didn�t give a tractor year or fuel type but probably 25�-30� is right in the ball park for a good running tractor�

[email protected]

If you want to use a timing light, you would have to measure the flywheels outer circumference, then divide that number by 360 to get how many inch fractions per degree, them measure off and make timing marks at like 0 (TDC) and 20, 25, and maybe 30 BTDC for the timing light to see. I use an old fashioned timing light on the left plug wire, of course, and then you can see how much advance youre running at. Theres been a lot of long winded discussion on here about the type of timing lights and their impulse and number of cylinder settings etc etc, but my old fashioned light works best for me.

I assume you have the initial start timing about right so she starts and dont kick back, and are just wonderign about how far the advance timing is over the start right?????

Many of those mags, depending on the type and coupler, are run time advance (or lag angle) mark (at rear coupler) at straight up being 12 1/2 degrees of advance, and each mark is 5 degrees, so another 2 1/2 marks left (CCW) of center would be an additional 12 1/2 degrees of advance, making that 25 total advance if set there. I personally think 30 is too fast (for a stock tractor), but that depends on the RPM and compression and fuel etc etc so if 30 works on that tractor, thats fine.

Why do you think its slow????? ?? If its set too fast, that can be counterproductive and hard on the tractor. Unless youre runnign at very high compression at very high RPM etc., the 25 degrees BTDC range is usually fairly close.

Lemme know, Good Luck n God Bless

John T Nordhoff in Indiana