WD45 Engine Update - Success!
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=134313
Printed Date: 07 Nov 2025 at 3:28pm
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Topic: WD45 Engine Update - Success!
Posted By: Dave(inMA)
Subject: WD45 Engine Update - Success!
Date Posted: 26 Jan 2017 at 3:54pm
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Back in October I started a thread about a miss I am hearing in the engine of my WD45. Here's a link to that thread for anyone who might want to read it again: ( http://www.allischalmers.com/forum/forum_posts.asp?TID=130424&KW=Dave%28inMA%29&PID=1078377&title=wd45-engine-diagnosis-needed-update-nov-3#1078377" rel="nofollow - http://www.allischalmers.com/forum/forum_posts.asp?TID=130424&KW=Dave%28inMA%29&PID=1078377&title=wd45-engine-diagnosis-needed-update-nov-3#1078377 ) I've made some progress working through the suggestions in that thread and wanted to see what you fellows think at this point. 1. I've adjusted the valve clearances to 0.012" - did this with the engine warm but not hot. I found that the rocker arm ends that drive the valves were badly worn - I had clearances up to several times the desired amount. 2. I have replaced spark plug wires and the dissy cap and put in a set of plugs that ran fine in another engine. Also replaced points and condenser. 3. Converted the electrical system to 12 neg ground with help from our friend Steve Barbato. 4. Checked the compression with the engine hot, all plugs removed, throttle wide open - I'm seeing 70 psi +/- on the first engine revolution and 85-90 psi on the second. All of which leads me to a couple of questions: 1. Should I replace the rocker arms? Or can I grind the surfaces flat(?) and re-use the ones I have? 2. What do these compression results suggest? Thanks for any and all help! Dave
------------- WC, CA, D14, WD45 |
Replies:
Posted By: SteveM C/IL
Date Posted: 26 Jan 2017 at 6:26pm
| They can be ground with the proper tooling.You can just pay attention to where you place the feeler and adjust that way...but it is a little trickier. |
Posted By: B26240
Date Posted: 26 Jan 2017 at 6:30pm
| As Steve said takes special tooling to grind rocker arms. they need to have a curve to them not flat. Machine shop that does engine work such as valve grinding etc will have the proper equipment to do this. |
Posted By: Dave(inMA)
Date Posted: 26 Jan 2017 at 6:35pm
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I was wondering about the contour of the rocker arm surface! Thanks for the information. Dave ------------- WC, CA, D14, WD45 |
Posted By: Gerald J.
Date Posted: 26 Jan 2017 at 6:56pm
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It often takes 4 or 5 strokes to get to the full compression pressure on the compression gauge. Making it in two looks fine to me. Gerald J. |
Posted By: Lon(MN)
Date Posted: 26 Jan 2017 at 6:58pm
| How about if you put a 150 grit in your belt sander, clamp the sander in the vise and sand until it looks good? |
Posted By: LeonR2013
Date Posted: 26 Jan 2017 at 7:48pm
| It takes a good eye and a real steady hand. |
Posted By: Dave(inMA)
Date Posted: 26 Jan 2017 at 9:41pm
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Hmmm - wondering what the compression for that engine should be?? Lon and Leon - are you talking about reshaping the rocker arms? ------------- WC, CA, D14, WD45 |
Posted By: IBWD MIke
Date Posted: 27 Jan 2017 at 11:07am
| I think a new WD45 had 130 PSI compression. Mine with M&W pistons makes 145, the other one with kit from Tony 150. The propane engine made 190 on the best cylinder. It is 4&1/8 bore with flattops. My rough calculations say 10 to 1 ratio. |
Posted By: Allis dave
Date Posted: 27 Jan 2017 at 11:23am
| A WD with a WD crank and pistons should make 110PSI. They were only about 5.5 or 6:1 compression ratio |
Posted By: Dave(inMA)
Date Posted: 27 Jan 2017 at 2:10pm
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Hmmmm....based on that input (thanks, guys) it sounds as though my engine is a little weak! Though maybe I should re-do the test as I only measured through 2 compression strokes. I had understood that I should read the psi on the first compression stroke, but now I've read information that says to spin the engine until the reading peaks. ------------- WC, CA, D14, WD45 |
Posted By: Allis dave
Date Posted: 27 Jan 2017 at 2:37pm
| I am not an expert, but unless you're having power or starting issues, I don't think anyone here would worry about 20 PSI as long as the cylinders are all even. |
Posted By: Dave(inMA)
Date Posted: 27 Jan 2017 at 4:05pm
Thanks, Dave. I agree - I've always understood that consistent readings are more important than the actual number. But I have read differing advice on how to conduct the test, though most sources are saying to spin the engine until the reading maxs out. So, just for fun, I'm going to do it again following that advice.  ------------- WC, CA, D14, WD45 |
Posted By: Dave(inMA)
Date Posted: 28 Jan 2017 at 10:58am
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OK. First an update on the compression readings. I redid them this morning - cranked the engine until the readings stabilized. Here's what I got: #1, #2 110 psi #3, #4 115 psi These seem pretty consistent to me and not too dusty for a 60 year old engine! Next I pulled the rocker arm assembly off to inspect the surfaces on both ends of the arms to see how much wear is there. Here are 3 photos, the first of the lifter end, the last two on the valve end: http://s28.photobucket.com/user/pilotdave1/media/20170128_153813404_iOS.jpg.html" rel="nofollow">  http://s28.photobucket.com/user/pilotdave1/media/20170128_153847497_iOS.jpg.html" rel="nofollow">  http://s28.photobucket.com/user/pilotdave1/media/20170128_153927032_iOS.jpg.html" rel="nofollow">  The lifter end surface looks fine to me, but you can see the wear on the valve end surface. All of the rockers seem worn to the same degree. So the question of the morning is: is this enough wear to justify regrinding or even replacing the rockers? Thanks for your help. Dave ------------- WC, CA, D14, WD45 |
Posted By: LeonR2013
Date Posted: 28 Jan 2017 at 11:17am
| Very normal wear on this age engine and certainly renewable. Depending on whether your're better with a file or grinder you can do them by hand if you're needing to save a little money. The best way to do it of course is to have ground by the head shop. I did my 45 by hand, taking my time, and it's been 5-6 yrs. now and no problem at all. But Joe and I think alike and pinch our pennies, Joe because he has money, and me because I have none. LOL The condition they are in, you really do need to resurface them. You'll get a better valve adjustment, more power and it will run smoother. PM me if you have any questions. |
Posted By: Dave(inMA)
Date Posted: 28 Jan 2017 at 1:33pm
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There's some penny pinching going on here as well! I'm going to compare pricing for a machine shop repair vs new and then think about whether to try this on my own. ------------- WC, CA, D14, WD45 |
Posted By: Ted J
Date Posted: 28 Jan 2017 at 2:52pm
That's what I'd do too.  You've got nothing to lose and everything to gain. Just slow and careful...kinda like your first date..... The compression looks just great, they are all within spec. Once you get it running, do it again cold and then get it up to temp and do it again. Then come back and tell us what you have. Should be just a little drop, but they should all be within 10psi. That is acceptable. At least it is to me and the way I learned...... ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: Dave(inMA)
Date Posted: 28 Jan 2017 at 4:53pm
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Thanks for the advice and encouragement! I ran the compression test with a warm engine - not run hard but with the temp needle up around 120*. Haven't tried it cold yet. ------------- WC, CA, D14, WD45 |
Posted By: Dave(inMA)
Date Posted: 05 Mar 2017 at 6:47pm
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Today I pulled the rocker arm assembly, took photos, and disassembled it so I could grind the rocker arm pads. After studying the pad shape a LOT, I used the side of a fine wheel on my bench grinder - all eight done in about 5 minutes using light passes rotating the arm against the wheel. Reassembled the rocker arm assembly and re-installed it. I've set the clearances to 0.013 cold....I believe the spec if 0.012 hot. Once all the fluids are back in the old girl, we'll see how it sounds! ------------- WC, CA, D14, WD45 |
Posted By: Allis dave
Date Posted: 06 Mar 2017 at 6:50am
| Dr. Allis always says to set them to .015 cold then they'll be at .012-.013 by the time they're warm. |
Posted By: Dave(inMA)
Date Posted: 06 Mar 2017 at 6:53am
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Thanks, Dave. I'll reset them. ------------- WC, CA, D14, WD45 |
Posted By: Dave(inMA)
Date Posted: 06 Mar 2017 at 5:34pm
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Alrighty, then! Finished replacing fluids, readjusted the valve clearances to 0.015 cold and fired up the tractor. That slight miss I had before? GONE! Starts and runs nicely. Next step - hook onto the plow and give it a workout. That'll happen soon - waiting for the weather to decide if it's going to be spring or winter!! Thanks for all the help, guys. ------------- WC, CA, D14, WD45 |
Posted By: LeonR2013
Date Posted: 06 Mar 2017 at 7:11pm
| After you've run it a bit it's always a good idea to readjust the valves. You think you have them even and doggone if there won't be one or two loose. I've developed a way to do it that is very accurate, so if you're interested PM me and I'll get back to you. Explanations can take up a lot of room. Congratulations on getting it running. Yahoo! |