Jubilee Timing; Stalls at Idle RPMs

mrlewp87

New User
Sprung for a cheap timing light, strobe only type. RPMs I can get from new Proofmeter. (having fixed the issue with the undersized drive end and tab, unaware there is an adapter for sale. But I digress ....) Almost nothing goes smoothly for me, and this was no different. Reasons;
1) The numbers on the flywheel were not readable. Even after
using a couple means of cleaning the area visible thru the
peephole, it was all a blur. Two things:
a) I could at least tell that the values were jumping within
about a 5 - 7 degree range, at least according to the
firing of the strobe light.
b) perhaps a better timing lite would emit a shorter burst
of light, better for freezing the markings for a clearer
view of them.?
2) Our "Hey Jube" (that"s mine! You can"t use it! Ha) would
stall at anything below 625 RPMs. That"s a problem since
youre supposed to set the timing to 8* BTDC, when at a
450-475 RPM idle.
I tried removing the oil cup from the air filter, in case of poor suction. It"s not the fuel cap vent issue that I just learned of. There was at least 3" of fuel in the tank, so though gravity-fed
I can"t see any causes there. The stalling was instant when dropping the RPMs, vs. any lag time taken to respond to any poor fuel supply concern.
Fast forward, having added extra scored markings at 5, 8, and 20 degrees for visibility; and since I can"t get the RPMs below 625, where the ideal is 8* BTDC @ 475 ....... And,
you know the value is going to rise as the RPMs rise, then;
*> I set the timing to around 10* BTDC / @ 625 RPMs.
I then upped the throttle to reach 1200 RPMs, at which the manual shows a max. acceptable of about 20 dgrs. Again the best views I got were shaky, but I was getting a high end value of about 22 dgrs. IF I were to lower that reading, it"s nearly certain that my reading at 675 RPMs might fall below the ideal for 475 RPMs.
3) have I reached an OK balance? Or better to achieve
the advised degrees for 1200 RPMs ? (I"m not good
with pushing the ol" Jube to 2000)
4) Do I go back to the lowest RPMs without stalling, and
just go by ear?
5) is over-heating a concern when the timing in degrees
is too low, too high.? Or both?
An FYI; I went out a mowed some thick, overgrown pasture grass for a solid 1.5 hrs. after timing set as noted above (after
"Fast forward" notes. The water temp eventually reached a scant 1/8th" from red. It was a lot of tough mowing, but I tried to keep her moving smoothly.
I also upped it to 1700 RPMs, 200 above PTO minimum. That OK? Points being it never really over-heated, and seemed to run smooth as can be expected for an old girl. I reminded myself that its still only a 26 HP (?) tractor, and suppose its expected to bog down in the thick and tall grass. Agreed?
I know I"ve posed many points/ questions. Anything answered or commented on is appreciated.
 
I'm giving you a stab in the dark here, but I don't think
the lack of low idle is timing related. I would think carb.
There are two carb circuits, one for idle and one for power.
I would think your idle circuit is not set correctly or needs to be cleaned.
Idle screw on a MS carb turns in to enrich, out to lean.
A lean running carb can cause moderate overheating as well.
Doesn't sound all that far off in the grand scheme of things.
I've ran worse when I had to.
Don't let it overheat and don't entirely trust that gauge.
 

x2 on carb idle problems. Get those corrected and then attack the timing issue. As Royse said, it may just be a simple idle screw adjustment.
 
I"ve seen this "MS" before, in reference to the carb. Not sure what it means. And the term "circuits"? I"d assume talking fuel, not electrical. I"ve adjusted idle screws before on cars, and never thought to try that on our JuJuBee.?? I"m not able to see the replies now, and dont want to risk losing my comments here. So what was that other screw called, and what do I need to know to make adjustments, if any are to be done?
 
MS = Marvel Schebler, the brand of the original carb.
If you have a replacement Zenith carb or something else,
adjustments will be different.
The circuits are fuel circuits as you say, not electrical.
This is simplified and off the top of my head, so consult a manual!
There are three adjustments. The idle speed screw which
should be fairly evident, it holds the throttle open.
The main fuel adjustment is the large thumb screw adjustment.
That one is used to adjust fuel flow under load and at higher RPM.
Then there's the idle air screw, which is angled in from the side.
This one adjusts the fuel at idle. It is backwards from most cars
and most other carbs for that matter.
Turning it out gives you a lean mixture/less gas/more air.
Normally it is in the neighbor hood of one to on and a half turns
out with just 1/16 of a turn making a difference in how it idles.
If it doesn't change anything, the carb needs to be cleaned.
Adjust this for the fastest idle, then turn the idle speed screw
down to get to a lower idle. Then do it again.
You may have to do it several times.
 


Where are you getting the 8* timeing setting from? I've only seen a 4* setting spec. at 450-475 RPM for the Red Tiger engine. This isn't causing your stalling issue though.As others have said-dirty carb.
 
x3 for a dirty or needing adjustment carb
get that straightened out first.
While timing too retarded will cause an idle stall, it's probably your carb.
an erratic timing light usually means an ignition problem, but in this
case it's probably plugs fouling randomly from the bad carb.

Yes, it's 8 degrees initial for a NAA, but getting em down to 475 rpm, which is sloooow can be a pain.
if your advance is working properly, it's much easier
to find the NAA 29-31 degrees total. rev it up slowly with the timing light on, you will see when the advance has limited out.
set it at 29-31 degrees, lock it down and you're done.
IMO, The timing being right at the working RPMs is the most important.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top