Weak spark
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=186125
Printed Date: 26 Sep 2025 at 3:23pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Weak spark
Posted By: D14JIM14
Subject: Weak spark
Date Posted: 31 Jan 2022 at 1:34pm
|
I have a wd45 non running for 30+ years . New battery , new plugs , pts and condenser and coil. Cap and wires . The spark is very week at the end of plug wire. Using screwdriver from wire to metal . Any solution ? Carb is rebuilt also . Turns over well . |
Replies:
Posted By: dp7000
Date Posted: 31 Jan 2022 at 1:53pm
| Did you replace rotor button? |
Posted By: tadams(OH)
Date Posted: 31 Jan 2022 at 1:54pm
|
what kind of spark plug wires?
|
Posted By: D14JIM14
Date Posted: 31 Jan 2022 at 1:57pm
|
Copper wires Yes replaced rotor and cap |
Posted By: dp7000
Date Posted: 31 Jan 2022 at 2:16pm
|
Points could be too close or too wide? What’s the spark in the points look like? Wires to and from coil could be broken or breaking down? |
Posted By: D14JIM14
Date Posted: 31 Jan 2022 at 3:10pm
|
Thank-you, I suspect the old wires to and from coil could be it . Pts have good spark . |
Posted By: MACK
Date Posted: 31 Jan 2022 at 7:59pm
| 6 or 12v? MACK |
Posted By: steve(ill)
Date Posted: 31 Jan 2022 at 8:41pm
|
Dont use a screw driver.. Put one plug in the plug wire and ground it with a battery jumper cable with clamps to a good ground. You replaced the point, and the timing is checked ? Fire the plug at TDC ? ------------- Like them all, but love the "B"s. |
Posted By: Steve in NJ
Date Posted: 01 Feb 2022 at 8:38am
|
Pop the cap off, grab a hold of the rotor and see if you have side to side wobble. If you do, the Distributor's mainshaft bushing is worn. This causes the dwelll to change constantly because the rub block on the points is not consistant in opening and closing the points causing low voltage and also can cause the engine to run lousy if it does start and run. The Distributor will need to be rebuilt. If there's no side to side movement, I would inspect the ignition circuit for breaks or bad connection/corrosion at the ignition switch itself. You said it sat for 30 years, so its probably a connection or corrosion issue. Clean up the breaker plate in the Distributor. To do a quick troubleshoot, you can temporarily run a new wire from the Ignition switch to the coil and bypass the original circuit to see if spark increases. You also might just have a bad set of points. There's a lot of Chinese junk out in the aftermarket in ignition parts. If you need a new wire set, we offer quality wire sets, and Distributor rebuilding if needed. HTH Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: D14JIM14
Date Posted: 01 Feb 2022 at 1:01pm
|
Thanks to everybody ! I'll start trouble shooting . I grounded the plug as suggested and still very week . Spark at pts is strong . |
Posted By: steve(ill)
Date Posted: 01 Feb 2022 at 7:11pm
|
are you saying you think the spark is so weak that the tractor DOES NOT START ? I just did replacement on a CASE 530... plugs, coil , point, rotor, cap.... It starts and runs fine, but the spark at the PLUG is nothing to brag about........ plug wires are HARD and 12 years old... i might replace them sometime just as preventative maint.. any voltage going thru the POINT, has already gone TO the COIL and OUT of the COIL on those 12v wires. ------------- Like them all, but love the "B"s. |
Posted By: MACK
Date Posted: 01 Feb 2022 at 8:18pm
| Pull coil wire out of distributor and hold next to block. Check spark out of coil. If you have good spark then, problem is in cap or plug wires. MACK |
Posted By: DaveKamp
Date Posted: 02 Feb 2022 at 4:14pm
|
What NJ Steve said- distributor shaft base bushing wears on these, gets sloppy, and 'walks laps' around the bushing, and you get really lousy point action. The other thing to expect, is a crap condenser... brand new, out of the box, about 70 % failure rate... You have enough spark when it scares you to hold the plug against the block... snappy, angry blue-white pop means you're ready. ------------- Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest. |
Posted By: D14JIM14
Date Posted: 07 Feb 2022 at 1:10pm
|
This Iis a 6v positive ground system. Should the wire from the distributor go to the negative or the positive side of the coil ?? |
Posted By: GARY1967
Date Posted: 07 Feb 2022 at 3:29pm
|
Hello, positive wire goes to distributor. |
Posted By: steve(ill)
Date Posted: 07 Feb 2022 at 3:42pm
|
---- my mistake on polarity........... ------------- Like them all, but love the "B"s. |
Posted By: TramwayGuy
Date Posted: 07 Feb 2022 at 5:55pm
| Try it with the old condenser. The failure rate right out of the box is fairly high. |
Posted By: D14JIM14
Date Posted: 07 Feb 2022 at 9:01pm
|
Unfortunately I don't have the old condenser ! Ok I got 2 answers on the question of if the distributor goes to the positive side of the Coil ? It's a positive ground system . |
Posted By: steve(ill)
Date Posted: 07 Feb 2022 at 9:23pm
|
OK Jim... i see the problem... I think the correct way to wire a coil is to have the battery HOT wire connected to the corresponding coil terminal... If your NEG terminal is HOT ( old 6 volt positive ground), then that connects to the NEG terminal on the coil, and the POSITIVE would go to the point ................ My mistake. ------------- Like them all, but love the "B"s. |
Posted By: D14JIM14
Date Posted: 08 Feb 2022 at 7:48am
|
Thanks Steve ! That's my evaluation too . I'm not great on wiring though . The col had been robbed when I got the tractor . Wanted to be sure . Jim |