8070 tach
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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=148407
Printed Date: 21 Aug 2025 at 9:43pm
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Topic: 8070 tach
Posted By: AC720Man
Subject: 8070 tach
Date Posted: 12 Mar 2018 at 6:50am
A friend of mine purchased a nice 8070. The tachworks correctly at idle,however as power is supplied beyond half throttle it pegs to 2500 rpm. Hour meter is working. Other than the possibility of a bad tach is there anything else that can cause this? Can the hr meter still be accurate? ------------- 1968 B-208, 1976 720 (2 of them)Danco brush hog, single bottom plow,52" snow thrower, belly mower,rear tine tiller, rear blade, front blade, 57"sickle bar,1983 917 hydro, 1968 7hp sno-bee, 1968 190XTD |
Replies:
Posted By: randy
Date Posted: 12 Mar 2018 at 8:23am
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There is a pick up sensor next to the fuel cap between the frame rail and the engine block. I might be bad. It picks up the speed from the flywheel spinning. ------------- CA WD WD45 D17 D17 Diesel 7060 8050 8070 |
Posted By: AC720Man
Date Posted: 12 Mar 2018 at 10:48am
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Thank you! ------------- 1968 B-208, 1976 720 (2 of them)Danco brush hog, single bottom plow,52" snow thrower, belly mower,rear tine tiller, rear blade, front blade, 57"sickle bar,1983 917 hydro, 1968 7hp sno-bee, 1968 190XTD |
Posted By: SteveM C/IL
Date Posted: 12 Mar 2018 at 12:35pm
| try adjusting it first.I think book said 1 turn out from contact.Plug/unplug connector a few times to help continuity. |
Posted By: AC720Man
Date Posted: 21 Mar 2018 at 6:39pm
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I unscrewed the sensor and it is not damaged. Appeared to be correctly adjusted. I measured across the leads and it measures 200 ohms. I was told this is within specs but I would like to verify. I screwed the sensor back in and adjusted it. The hour meter continues to work, however the tach jumps up to 1,500 upon startup, any throttle above that results in burying the needle to 2,500. With that being said, is there anyone that repairs these electronic tachs? ------------- 1968 B-208, 1976 720 (2 of them)Danco brush hog, single bottom plow,52" snow thrower, belly mower,rear tine tiller, rear blade, front blade, 57"sickle bar,1983 917 hydro, 1968 7hp sno-bee, 1968 190XTD |