weak spark at plugs

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Waif
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Re: weak spark at plugs

Postby Waif » Tue Mar 13, 2018 9:24 pm

Cubfriend wrote:
Waif wrote::Gap new plugs .23 ,install ,make sure tranny is in neutral....Then gennntly kick left front tire. Then fire it up! :{_}:


Did you mean to say .023?

Ouch! And yes. Thanks for catching it.
Looked at my note recently used to gap with before I posted it too......... :cry:
Bet it ain't the first time.

bobscooter
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Re: weak spark at plugs

Postby bobscooter » Thu Mar 15, 2018 9:02 pm

Well guys tried all that was suggested with no success , as I said old girl must be tired only thing I have not tried is pulling it, may try that Saturday .

Landreo
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Re: weak spark at plugs

Postby Landreo » Fri Mar 16, 2018 9:49 am

bobscooter wrote:need help with cub, weak fire at plugs , new points set at 20 thousands ,new condenser , coil ,plugs and wires, on tdc no 1 is about 2 oclock in distributor tdc clockwise fo is 1342 have good fire at coil, points, but weak at plugs, it will not start with a squirt of ether, one of those stumpers that may be so simple any help thanks



Did it run before you did all of that?

What is a good spark? To me it is a pencil lead wide spark when the wire is held 1/4 inch from the frame.The color does not matter. A weak spark is the size of a piece of thread.

Is the battery good and fully charged especially if it is 6 volt? Trying to pull start it will not do anything better than what a good battery will do.

Did you replace the cap and rotor? A bad/dirty cap or rotor will drain the spark.

Spark plug wires on correctly and in the correct firing order?

Did you take the distributor off the tractor and not get it re-timed correctly? Did you check the timing?

Did you try to start on ether only? A flooded engine may not start with ether. Try closing the fuel valve, throttle wide open, choke open, and crank the engine to clear the cylinders for 10 seconds, then spray a little ether.

bobscooter
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Re: weak spark at plugs

Postby bobscooter » Fri Mar 16, 2018 7:09 pm

using a new group 31 battery have tried all you have mentioned still no luck

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Indy4570
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Re: weak spark at plugs

Postby Indy4570 » Fri Mar 16, 2018 7:35 pm

try checking to see if the coil is properly grounded. was an issue for me once.
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staninlowerAL
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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"
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Re: weak spark at plugs

Postby staninlowerAL » Fri Mar 16, 2018 8:39 pm

Did you get the compression test results? Wet or dry or both? You may have low compression (or maybe none on one or more cylinders if the valves are not sealing).

bobscooter
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Re: weak spark at plugs

Postby bobscooter » Sun Mar 18, 2018 9:02 am

about 60 psi but will not hold, when I first got the tractor had the same 60 ,but it held the compression then ,tractor set for a while till I got time to work on it ,maybe this is the problem ,put some oil in cyl tested again with no help , tried again yesterday same thing

Waif
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Re: weak spark at plugs

Postby Waif » Sun Mar 18, 2018 9:43 am

Huh. Adding oil did not raise pressure...... Might not be ring related yet.
Here's some posts to browse.....Ricky's suggestion of using regulated air is interesting.http://farmallcub.com/phpBB2/viewtopic.php?t=40226

Bobscooter: if your old coil worked,and you still have it ,you could swap it out with your new one.
Another member had intermittent spark with a new coil. Trying the old one allowed tractor to run.
A set of known good used parts can help when installing new ones in an ignition system that suddenly won't work ( due to defective new parts)Even a condenser can cause headaches when a new one is bad.

bobscooter
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Re: weak spark at plugs

Postby bobscooter » Sun Mar 18, 2018 4:39 pm

there was no coil on the tractor when I bought it, new coil has good fire, even bought another set of points and cond, changed out the new autolite plugs, put in new d 21 plugs spark is brighter ,got new plug wires ,shot of ether in carb no luck ,checked compression around 60 psi on all 4 cyl but will not hold , valves may need attention, pulled valve cover valves not stuck but may not be seating as they should , thanks for all info you guys are sending believe me I am doing what you all have mentioned plus more

Waif
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53 F-Cub W/Loader.
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Re: weak spark at plugs

Postby Waif » Sun Mar 18, 2018 5:17 pm

bobscooter wrote:there was no coil on the tractor when I bought it, new coil has good fire, even bought another set of points and cond, changed out the new autolite plugs, put in new d 21 plugs spark is brighter ,got new plug wires ,shot of ether in carb no luck ,checked compression around 60 psi on all 4 cyl but will not hold , valves may need attention, pulled valve cover valves not stuck but may not be seating as they should , thanks for all info you guys are sending believe me I am doing what you all have mentioned plus more


That low of compression is not helping. You are on track to focus on getting that resolved.

Good spark ,does not mean spark where and when it needs to be. A goofy coil firing in between t.d.c.' s is the impression I had from defective new coil.
Like a wandering timing symptom... due to staccato firing of defective coil. (Should you get compression up above eighty and tire kick don't help.... :mrgreen: )

staninlowerAL
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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"
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Re: weak spark at plugs

Postby staninlowerAL » Sun Mar 18, 2018 5:44 pm

If you just want to start the engine and everything is set right as you stated (firing order correct, timing, #1 plug wire to correct tower on dist cap, no sticking valves other than compression leakdown) you may be able to pull start it with the low compression. Pulling by connecting to the front axle/bolster risks breaking something so connect at the drawbar or somewhere other than the front. Compression may improve after it's run for a while. Likely you're looking at cleaning up and reseating the valves at a minimum.

bobscooter
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Re: weak spark at plugs

Postby bobscooter » Sun Mar 18, 2018 6:10 pm

I could very well have over looked something , but I have checked and rechecked, as you know some times it is so easy to over look something so SIMPLE

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Re: weak spark at plugs

Postby bobscooter » Fri Mar 23, 2018 7:33 pm

well guys still no start, will try tomorrow , have another question, I have a cub lowboy best I can read 25687-j think it is around 1963 has a 1 pt hitch, would like to switch the hitch to a regular cub about same year model any one have any info if it will work before I go through all the trouble to take off if it will not work, thanks

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Re: weak spark at plugs

Postby tmays » Fri Mar 23, 2018 7:44 pm

bobscooter wrote:well guys still no start, will try tomorrow , have another question, I have a cub lowboy best I can read 25687-j think it is around 1963 has a 1 pt hitch, would like to switch the hitch to a regular cub about same year model any one have any info if it will work before I go through all the trouble to take off if it will not work, thanks

No, won’t work
Thomas

staninlowerAL
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Posts: 3741
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"
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Location: AL (Southwest)

Re: weak spark at plugs

Postby staninlowerAL » Fri Mar 23, 2018 8:10 pm

Yep, tmays is right. Some parts will interchange though. Check the parts catalog, it will tell you what fits which Cub.


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