d-17 erratic firing ??
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=161762
Printed Date: 23 Jun 2025 at 3:05am
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Topic: d-17 erratic firing ??
Posted By: tractorboy
Subject: d-17 erratic firing ??
Date Posted: 09 Jun 2019 at 4:19pm
| That d-17 I rebuilt last winter has got one last bug to get out. I've got about 15hrs on the rebuild: mostly from a parade/ tractor show & a little hay making. I actually got compliments on how smooth it ran, these folks only heard it at idle. The problem is at 3/4 to wide open throttle it will pop, not backfire just an irregular pop from the exhaust.Here's what I have done to try to fix the problem 1] got a rebuilt carb from Dans tractor supplies, he's supposed to be one of the best- was supposed to be preset on a running engine, did'nt help tried some adjusting myself, no luck 2] changed plugs, napa points- condenser, took cap & wires off my wd45 no luck 3] valve lash has been checked 4 times per manual 4] plenty of gas flow- the tank was cleaned & sealed during rebuild I bought a timing light,I was close by ear, but it looks like it is not firing at the same place I'm warmed up & pretty much wide open during this check. Should the mark be rock steady when it fires?? Yes the dist. has slack in it but so do my other 6 AC's they all run like a swiss watch. The dist shaft has no wobble just a lot of back-lash. Sorry for the long post- shes driving me crazy& to the poor-house!!!!! |
Replies:
Posted By: Bradleytrench
Date Posted: 09 Jun 2019 at 6:21pm
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I would check the distributor advance weights and springs. Id also check to see how much play is in the distributor shaft and bushings. Bobby Mo ------------- 1 WD45D, 1 A2 GLEANER, Wd w 33mounted corn picker |
Posted By: tractorboy
Date Posted: 09 Jun 2019 at 7:17pm
| I checked the advance wts & springs, they were clean & free so I gave them a little shot of wd-40. There is no wobble or side to side play, but there is back-lash, just don't understand why the other 6 run fine with the back-lash. |
Posted By: Boss Man
Date Posted: 09 Jun 2019 at 9:21pm
| When you rebuilt the motor did you use new valve springs or check the spring tension? Where the guides replaced? |
Posted By: MACK
Date Posted: 09 Jun 2019 at 9:23pm
| Is it a early D17 with power steering? If so drive gear on governor shaft Is worn out. MACK |
Posted By: DaveKamp
Date Posted: 10 Jun 2019 at 9:56am
A bad condenser, weak point spring, or weak valve would all be appropriate suspects, as would be a tiny crack or leak in an exhaust manifold, but what you've noted is the best clue here... you're not getting a steady ignition event. Weak point spring, bad condenser, and dirty points would be my first, simply becausue they're quick and easy. The Delco-Remy distributor in the Allis engine develops slop, and as you noted, usually in the radial plane, and this slop means that the point cam's lift point is directly affected. Radial slop means the cam lifts the points inconsistently, AND, the ignition dwell time is wrong, which at high speed, can cause a really blatant miss. Vertical motion may not SEEM like it can cause timing issues, but the timing gears below will cause the shaft to kick around, again causing an unstable event... See the gears on the bottom of the distributor? if it's walking vertically, your timing will change. As Mack noted, the governor gear may also be worn... look at how the distributor drive works- from the governor housing, a horizontal shaft driven by governor gear, to a 90 degree worm (rather than bevel) drive. When ANY of these gears exhibit slop, the result is opportunity to affect timing event stability. IF the governor gear is good, drive out the crosspin, remove the distributor drive gear, and install a thin washer or three between gear and housing, to take up the vertical slop, then reinstall gear and crosspin, reinstall, set timing, and try again. ----- Another thing to note... how BAD is this occasional 'pop'? Many do not realize that running at high idle (meaning, full governed speed) with no load, includes a little popping. Why? Because the engine is spinning fast, the cylinders want to fill completely, but the governor is restricting the flow of fuel. Why? Because there's NO LOAD... the throttle, being closed, is limiting fuel, thus, it's pretty darned lean in that chamber. It wasn't designed to be a smooth running engine at full speed, while doing no work... it was designed to be smooth and efficient under a HEAVY load... so, Put a load on it... make it work. Does it still pop? If so, then explore the situation. If not, call it normal. ------------- Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest. |
tractorboy wrote:Posted By: tractorboy
Date Posted: 10 Jun 2019 at 5:50pm
| Thanks to all, I guess i'll try another set of napa points/condenser. If that doesen't do it, I'll try the vertical motion fix, thanks Dave. It doesn't have power steering. I just wish it would run half as smooth as my worn -out oil burning/leaking, little to no oil pressure, WD-45!!! The pop is not a back-fire & is intermittant, also does the same thing under load [hay conditioner] . keith so.va. |