7045 tachometer
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=9214
Printed Date: 28 Sep 2024 at 5:45pm
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Topic: 7045 tachometer
Posted By: injpumpEd
Subject: 7045 tachometer
Date Posted: 09 Mar 2010 at 12:37pm
I am working on a 7045 for a friend of mine, and after replacing the alternator pulley, the tach reads fast. Changed to a different size pulley and got closer. My question is, are the tachometers adjustable to fine tune it against a photo-tach? I know aftermarket tachs can be adjusted a slight amount. thanks in advance, Ed.
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Replies:
Posted By: skipwelte
Date Posted: 09 Mar 2010 at 4:37pm
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No adjustment that Im aware of Ed, although Ive never looked for one either!!! If your getting some alternating current on top of the direct current it can cause the tach to read fast. Usually a slow reading tach was a slipping belt or a dying alternator. HTH
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Posted By: ac_bowsers
Date Posted: 09 Mar 2010 at 8:34pm
Sounds like a DrAllis question, I know that on ours and other I have been around usually the tach does not start reading RPMs until the alt. light goes off on the dash, a simple rev up with the foot throttle does the trick on ours. Our 7045 still has the orginal alt. on it and from being on the dyno it is within 50 RPMs +/- from being correct. However I do not think this is how they should normally operate, but the few around the neighborhood work that way that I have been around. AC current fluctuating on DC would make it read that way though s skip said.
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Pine Stock Farm "Home of the ALLIS" 35-WC-36-U-37-UC-47-C-49-G-57-D17-58-D17puller-63-D21-71-210puller-79-7045-83-8070-AA9675-BigTen-B10-310-1300fieldcult-snapcoupler imp.-longhopper blower,signs,etc.
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Posted By: 7060
Date Posted: 09 Mar 2010 at 9:07pm
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The tach in my 7060 gets to 3000 and maxes out when I think it should be around 1500. I am asking this for me and him both, could you use a digital multimeter to check for the AC current on the tach wire? My alternator was just rebuilt and it still does it so im still lost.
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Posted By: injpumpEd
Date Posted: 09 Mar 2010 at 9:32pm
these guys changed alternator to a Delco 1 wire, and yes it has to be revved up to excite it. The first pulley they had on it was too small, and read 3000 at around 2200. They have since changed the pulley to a larger one, to slow down the alternator, and it is within 100. I was hopeful the tach itself has and adjustment. thanks for the replies. Oh, do I need to call you Matt, to plan for the 210 coming to the show? Ed.
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Posted By: monitordoc
Date Posted: 09 Mar 2010 at 9:34pm
YES THEY CAN BE ADJUSTED. ONLY PROBLEM THEY HAVE TO BE COMPLETELY TAKEN APART. I HAVE BEEN REPAIRING AG ELECTRONICS FOR 25+ YEARS AND HAVE HAD MANY OF THESE APART. CHANGING PULLEYS SOUNDS GOOD ON THIS ONE. IN ANOTHER POST THE TACH READING 50% PROBABLY IS A CAPACITOR LEAKING.
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WD,D17-S4,180,D21
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