Farm Equipment - alternator vs tach

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alternator vs tach

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=8024
Printed Date: 18 Jan 2025 at 1:28pm
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Topic: alternator vs tach

Posted By: 7060
Subject: alternator vs tach
Date Posted: 12 Feb 2010 at 10:45pm

I am having trouble with my tach maxing out at half throttle on my 7060. It hits 3000 when it should be about 1500rpm. It has a different alternator on it and when I got it the tach wire was off. If the alternator was bigger or different would that cause it? I also have a 7050 that the tach runs at about 500rpm wide open and 300 idleing. What would cause such a low reading? Any help would be great

Replies:

Posted By: Denis in MI
Date Posted: 12 Feb 2010 at 10:58pm

are the pulleys factory size?

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1938 B, 1945 B, 1941 IB, 1949 C, 2 1938 WCs, 3 1950 WDs, 1951 WD, 2 1955 WD45, 1957 D-14

Posted By: 7060
Date Posted: 12 Feb 2010 at 11:06pm

They look to be the original size, but im not 100% sure. The 7050 and 7060 both have the same pulley. The 7060's alt was rebuilt a couple years ago.

Posted By: jaybmiller
Date Posted: 13 Feb 2010 at 7:17am

Sounds like the new alternator has a double the number of poles compared to the original.That would give you exactlry twice as many 'counts' per rev. This could be confirmed ny knowing the part number of the original and 'new' alternator. A slightly different pulley size(say 2 3/4" vs 3") would give a slightly higher or lower reading.

hth

Jay