49 cub wants to die under load

Farmall Cub Forum -- Questions and answers to all of your Cub related issues.

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Wed May 09, 2018 6:42 am

So with my timing light the pointer should be dead on the 16* mark
:tractor:

Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Wed May 09, 2018 8:33 pm

Now after running it to disk for about 15 min it completely quite and only has spark randomly. The mag has a nice blue arc so I’m assuming my coil is fine. I guess nobody wants to talk to me on here?
:tractor:

Waif
501 Club
501 Club
Posts: 686
Joined: Thu Aug 25, 2016 1:29 pm
Zip Code: 49343
Tractors Owned: 48 Farmall Cub "Seen Yore Dobbin"
53 F-Cub W/Loader.
Circle of Safety: Y
Location: Michigan

Re: 49 cub wants to die under load

Postby Waif » Wed May 09, 2018 8:47 pm

Rcook09 wrote:Now after running it to disk for about 15 min it completely quite and only has spark randomly. The mag has a nice blue arc so I’m assuming my coil is fine. I guess nobody wants to talk to me on here?

Hey ,I'm all for talkin ,but don't know what's goin on either.

It gives a bad coil symptom.

Your tractor runs. When under load and warmed up ...it cuts out. Yet starts up after cooling down.

Here's other ideas,but they are not going to remedy a bad coil.
Could be a wire or connection that expands with heat.
Do you have solid copper cored plug wires?
Are points clean and adjusted? Are points driven consistently? Rotor clean?

I'm leaning toward electrical/ ignition circuit somewhere. Cracked piece or intermittent short. Bad connection , bad condenser ect. Some component.
Only guessin tough.

Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Thu May 10, 2018 6:33 am

It’s def something in the mag the coil is strong even when hot. I’m so it’s got to be either rotor which is old, cap (old), spark plugs or wires
:tractor:

staninlowerAL
5+ Years
5+ Years
Posts: 3738
Joined: Fri Oct 29, 2010 11:34 pm
Zip Code: 36558
Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
Circle of Safety: Y
Location: AL (Southwest)

Re: 49 cub wants to die under load

Postby staninlowerAL » Thu May 10, 2018 8:21 am

Wear in the shaft will allow the points gap to vary. I had a dist once that had a broken wire internally. Depending on the position of the wire it would not fire, move the wire a bit and it ran OK. These are the hard ones to solve.

User avatar
Glen
5+ Years
5+ Years
Posts: 3330
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: 49 cub wants to die under load

Postby Glen » Thu May 10, 2018 5:18 pm

Hi,
The condenser can intermittently quit when the engine is cold or warm, but then there would be no spark.
I had one that made the engine run really rough, and would turn the spark on and off.

Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Sat Jul 28, 2018 10:51 pm

Hello everyone I’m back after having my first son and the old cub is still sitting in the shed in the same place not running and I want to get it going again
:tractor:

staninlowerAL
5+ Years
5+ Years
Posts: 3738
Joined: Fri Oct 29, 2010 11:34 pm
Zip Code: 36558
Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
Circle of Safety: Y
Location: AL (Southwest)

Re: 49 cub wants to die under load

Postby staninlowerAL » Sun Jul 29, 2018 8:27 am

Congratulations on being Papa. You've got another reason now to get the Cub up and running. Your posts above indicate that when the engine stops you still have a strong spark from the coil. "Now after running it to disk for about 15 min it completely quite and only has spark randomly. The mag has a nice blue arc so I’m assuming my coil is fine." Is this condition immediately after the engine stops and how/where did you determine the spark? How/where did you check the blue arc from the mag?

Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Sun Jul 29, 2018 9:01 am

Thank you tht is exactly y I want to get it going again. Since it died that one day discing it has not started since I have a nice arc from the wire coming from the coil to the engine block the spark plugs even seem to have pretty good spark they are new champions but no fire
:tractor:

Waif
501 Club
501 Club
Posts: 686
Joined: Thu Aug 25, 2016 1:29 pm
Zip Code: 49343
Tractors Owned: 48 Farmall Cub "Seen Yore Dobbin"
53 F-Cub W/Loader.
Circle of Safety: Y
Location: Michigan

Re: 49 cub wants to die under load

Postby Waif » Sun Jul 29, 2018 12:50 pm

It seems you are confident you have gas/air to cylinders ,timing and spark.
Try double checking spark plug gaps for .023inches. That's what fixed my sputter /pop(poomph and smoke) on a cylinder once in a while no starts last winter.

Last time my 48 died when working hard the mag was hot enough to fry an egg probably. Had to sit till cooled. A new coil is on reserve should it do so again.

staninlowerAL
5+ Years
5+ Years
Posts: 3738
Joined: Fri Oct 29, 2010 11:34 pm
Zip Code: 36558
Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
Circle of Safety: Y
Location: AL (Southwest)

Re: 49 cub wants to die under load

Postby staninlowerAL » Sun Jul 29, 2018 2:13 pm

After reading all the posts in this thread I do not see where you have a true mag ignition or a mag with an external coil. (A 49 would not have an external coil unless someone added it when the mag coil failed.) Can you post a picture? Also where and when did you check for the spark? Have you done a compression check/engine tune up? Low compression will make for loss of power, noticeably under load.

Rcook09
Posts: 31
Joined: Tue Mar 27, 2018 7:55 pm
Zip Code: 21778
Tractors Owned: 49 farmall cub
Cub cadet 104

Re: 49 cub wants to die under load

Postby Rcook09 » Tue Jul 31, 2018 7:55 pm

Ok my neighbor who is very knowledgeable in all old tractors came over he says I should have a nice blue arc for the plug about a 1/4 inch from the metal surface which happens to be the mag casing, which I do not have I have to have it almost on the casing before I get a weak spark. I have a good spark from the coil wire to the casing he knows a guy that works on nothing but mags so I think I’m going to take it to him I have to get this thing running deer season is upon us in md and I need to move this thing to hang my deer in the shed. Stan it has an internal coil
:tractor:

staninlowerAL
5+ Years
5+ Years
Posts: 3738
Joined: Fri Oct 29, 2010 11:34 pm
Zip Code: 36558
Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
Circle of Safety: Y
Location: AL (Southwest)

Re: 49 cub wants to die under load

Postby staninlowerAL » Tue Jul 31, 2018 8:14 pm

Internal coil needs replacing IMO. McDonald Carb. has them for under $100 or you can order from one of the site sponsors. In case you don't know, the mag will run the engine without any other electrical components since it creates electrical current by induction to power the engine.

User avatar
Shane N.
501 Club
501 Club
Posts: 3827
Joined: Wed Nov 22, 2017 6:24 am
Zip Code: 00000
Tractors Owned: .
1970 International 140 (Norman)
1972 International 140 (Keeferdoodle)
1949 John Deere A
1993 Ford 4630 W/Loader
1965 John Deere 110
1961 Cub Cadet Original

Sold Cubs..
1947 Cub #1447 (Arnold)
1949 Cub (Walt)
1950 Cub (piece of junk)
1952 Cub
Circle of Safety: Y
Location: N.C.

Re: 49 cub wants to die under load

Postby Shane N. » Wed Aug 01, 2018 5:34 am

staninlowerAL wrote:Internal coil needs replacing IMO. McDonald Carb. has them for under $100 or you can order from one of the site sponsors. In case you don't know, the mag will run the engine without any other electrical components since it creates electrical current by induction to power the engine.

Brillman has J4 mags for $44.75, I have one in Arnold and no problems with it in close to 2 years.
Every home is a school, what are you teaching?
You can't have a million dollar dream with a minimum wage work ethic.
Circle of Safety

Darryl Ovens
Posts: 9
Joined: Thu Aug 02, 2018 9:43 pm
Zip Code: 00000

Re: 49 cub wants to die under load

Postby Darryl Ovens » Fri Aug 03, 2018 2:23 am

I've seen faulty spark plugs give symptoms like that too. You say the plugs are new and it is even less likely that you would get 4 new plugs with faults, but could be worth trying another set, of known functionality ie working properly in another engine, even if just temporarily. Doesn't matter if the heat range is wrong so long as you only run it briefly (ie long enough to test it), but it would be worth ensuring they are near the right length ie not so short they don't reach far enough into the cylinder or so long that a valve or piston might hit them. I can't remember their positions relative to each other in the cub engine, (probably around 40 years since I had a cub head off).
This can happen if the plug insulation breaks down at higher voltages.
When the engine is running at higher speed or low load, the throttle is nearer shut, so inlet manifold vacuum is high and therefore engine compression is low. The voltage required to punch a spark through the charge in the cylinder is much lower at low pressures. But open the throttle and lots more air/fuel flows into the cylinders during the induction stroke, this results in higher pressure when compressed and therefore a much higher voltage is needed to drive the spark. The spark might be finding an easier path, either through the porcelain insulator in the plug (or somewhere else in the high tension ccts ie distributor or coil). (Faults in plugs will usually cause erratic misfires under load as the plugs will be different).

Some mags have whats called a safety gap, which is there to protect the coil from over voltage if a lead falls off or similar, sometimes this gap might have changed accidentally and if it is too small, it might become the easiest path when the compression pressure is high.
The safety gap is often just a small pointy bit of brass that is attached to the earthed body of the mag somewhere near the HT connection on the coil. (A small safety gap will usually cause the engine to stop firing completely while the throttle is open, as the one gap is common to all cylinders and consequently affects all cylinders the same).

In both of the two above conditions the "spark" can look good during the usual test at atmospheric pressure!

Chances are none of these are the fault, but its worth checking and ruling them out too.

Another point coil insulation can get porous with age, no problem if kept in dry conditions, but if a little dampness gets in that can cause the insulation resistance to reduce (esp when hot), leading to temporary breakdown at higher voltages. My grand father used to put HT coils and magnetos in warm dry places to dry them out/keep them dry, This can take days to weeks depending on how hot and how dry the place was. (Once it is dry a coat of varnish will help keep it out).

Story goes that he would do this when he was courting! We are not convinced it was just to dry out the coil or a good excuse to lengthen his stay! :D

Good luck
Cheers
Darryl


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: Dusty B and 5 guests