WD45 Runs! But timing? Backfire?
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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=169184
Printed Date: 17 Dec 2025 at 3:53am
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Topic: WD45 Runs! But timing? Backfire?
Posted By: ssccrab
Subject: WD45 Runs! But timing? Backfire?
Date Posted: 16 Mar 2020 at 11:26pm
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I've been working extensively on my seized 1955 WD45 to get it running. Today I got it running all the way up to full throttle! It runs rather smooth at low idle like it should, but about every second or so, I get a little bit of a "backfire" through the intake of the carb at low idle. At high idle, the backfiring speeds up. It isn't very heavy or loud sounding, and isn't shooting flames. I don't yet have the oil bath air cleaner bolted back on, just to test for problems like this, and I haven't moved it out of the shop yet. A couple of things: *Brand new points and condenser in distributor *Plug wires are correct for firing order (1-2-4-3) *Bright blue spark at plugs *Gas petcock is fully open at sediment bowl *"Brand new" carb (rebuilt, bought online) floods when not running. Floats are good, tested in hot water. I just shut the gas off when sitting. I believe it's either the distributor not rotated correctly, or the points need further adjusting. Looking for further advice from you all here. Thanks for the help!
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Replies:
Posted By: john(MI)
Date Posted: 16 Mar 2020 at 11:51pm
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How is the manifold gasket? While it's running, spray some engine cleaner, or something somewhat flammable around the manifold and see if there is any changes. ------------- D14, D17, 5020, 612H, CASE 446 |
Posted By: ssccrab
Date Posted: 17 Mar 2020 at 12:32am
| Exhaust/intake manifold? |
Posted By: B26240
Date Posted: 17 Mar 2020 at 6:27am
| After you confirm the timing is correct if it still is doing it I would think you have a intake valve that isn't seating properly. It may get over it after you run it some. |
Posted By: Lonn
Date Posted: 17 Mar 2020 at 6:52am
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Had that once on a WD. Turned out the piston pins were installed wrong, centered instead of off center and it cause it to backfire a little through the carb because a couple pins were rubbing the cylinder wall and I'm guess would heat red hot and cause the fuel/air mixture to detonate early. At idle is sounded fine but the more you worked it the worse it got. Just an odd thing and probably not what you are experiencing but if all else fails pull the pan and have a look at cylinder walls. ------------- -- --- .... .- -- -- .- -.. / .-- .- ... / .- / -- ..- .-. -.. . .-. .. -. --. / -.-. .... .. .-.. -.. / .-. .- .--. .. ... - Wink I am a Russian Bot |
Posted By: Dusty MI
Date Posted: 17 Mar 2020 at 6:57am
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Maybe the advance/retard in the distributer is sticking, try a couple drops of oil on it. Dusty ------------- 917 H, '48 G, '65 D-10 series III "Allis Express" |
Posted By: ssccrab
Date Posted: 17 Mar 2020 at 9:58am
| Thank you for the kind advice, everyone. I'll put these all to the test today and post when I find the source! |
Posted By: Eric B
Date Posted: 17 Mar 2020 at 12:57pm
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Check to see how much play is in your distributor shaft. I have dealt with two cases as such. In both instances the Pertronix ignition kit was the 100% cure. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |
Posted By: allisbred
Date Posted: 17 Mar 2020 at 2:31pm
| Also suggest to check valve clearance— my rocker shaft tube was so worn, it looked like a noodle while running. It would not hold a setting. |
Posted By: Ted in NE-OH
Date Posted: 17 Mar 2020 at 2:37pm
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Check firing order 1-2-4-3 ------------- CA, WD, C, 3 Bs, 2 Gs, WC, I-400, 914 |
Posted By: CTuckerNWIL
Date Posted: 17 Mar 2020 at 3:34pm
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I would start by pulling plug wires one at a time, to see if you can isolate one cylinder as the problem. If you find 2 that don't effect the running at just above idle, switch those 2 wires around. You'd be surprised how mwny people swear they had the plug wires right, but have 2 switched around. Check for slop in the upper bushing on the distributor. If you can wiggle the top of the shaft left to right at all, it's wore enough to replace, and you can never get your points set right. Where did you get the condenser? Off the shelf packaged kits have garbage for condensers and you can pull your hair till it's gone and never get it to run right. Buy a Blue Streak condenser at NAPA or put electronic ignition kit in. ------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: Boss Man
Date Posted: 17 Mar 2020 at 4:40pm
| I would do as said above and try to isolate it to one cylinder by pulling plug wires. Sounds like a valve issue. May clear up the longer it runs |
Posted By: FREEDGUY
Date Posted: 17 Mar 2020 at 5:54pm
| CTucker is probably correct, You've got 2 plug wires swapped :-) |
Posted By: ssccrab
Date Posted: 14 Apr 2020 at 9:27pm
| Just an update: I purchased a brand new exhaust/intake gasket set and installed, set bolts to 20 ft. lbs. torque. Completely rebuilt new plug wires. Got a new distributor cap. All new oil pan and valve cover gaskets. I also took the time to do an overhead set, and timed the engine to the flywheel mark. Put a little oil down the distributor. When I got it fired up, I advanced the distributor a bit too far and backed it off. I'm glad to say I've been doing a whole lot of mowing with it the past couple of weeks with this nice weather. Starts up every time on the first pull and never misses a beat. Sounds sooo good! Thank you all for your advice! |
Posted By: Dusty MI
Date Posted: 15 Apr 2020 at 8:44am
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I was going to mow lawn today for the first time this year. Got up this morning, and the ground is white, and it's still coming down. Dusty ------------- 917 H, '48 G, '65 D-10 series III "Allis Express" |
Posted By: Lonn
Date Posted: 15 Apr 2020 at 8:51am
Great to hear you got her purring along.  ------------- -- --- .... .- -- -- .- -.. / .-- .- ... / .- / -- ..- .-. -.. . .-. .. -. --. / -.-. .... .. .-.. -.. / .-. .- .--. .. ... - Wink I am a Russian Bot |
Posted By: ssccrab
Date Posted: 15 Apr 2020 at 9:05am
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It's clear and sunny where I am in east KS, but only up to about 55 today. I'd love to get back out. In the mean time, here's a short video of putting her to work. https://youtu.be/9laPpgA3GW4" rel="nofollow - https://youtu.be/9laPpgA3GW4
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Posted By: ac fleet
Date Posted: 15 Apr 2020 at 11:55am
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Ground white here today. ------------- http://machinebuildersnetwork.com/ |
Posted By: Eric B
Date Posted: 15 Apr 2020 at 12:55pm
That sounds really good, can't get any better than that! Your grass is short so your speed is OK. With tall thick grass I just can't go slow enough with my WD. I have to use my D14 for the brush hog. Thanks for the video. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |
ssccrab wrote: