Tach question
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Postmaster
Joined: Mar 2005
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From: Earth
Tach question
I picked up a gauge panel w/factory tach at the junkyard. Donor truck was a V8, the Bronco into which I put it is a straight six. Tach seems to be off by quite a bit - it shows ~300 rpm at idle when the truck is at ~600 rpm and shows 1,000 rpm at 35mph when it should (by my calculations) show ~1,500.
Is the tach different between V8 and L6 models? Any suggestions on how to rectify the problem?
Is the tach different between V8 and L6 models? Any suggestions on how to rectify the problem?
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Joined: Jan 2001
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From: Virginia
The tach works off the spark signal of the distributor. Since the v8 fires 8 times per 2 revolutions, and the I6 only fires six times per revolution, that's the difference.
I had a tach in a mustang that had a switch on the back for 4 6 or 8 cylinders. I have heard of guys talking on here that there may be a jumper on your tach that you can install or cut, that will convert it.
Whatever year truck you have, go up to that forum and do a search on tach and see if you can find some info about the jumper if there is one on your model.
I had a tach in a mustang that had a switch on the back for 4 6 or 8 cylinders. I have heard of guys talking on here that there may be a jumper on your tach that you can install or cut, that will convert it.
Whatever year truck you have, go up to that forum and do a search on tach and see if you can find some info about the jumper if there is one on your model.
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Postmaster
Joined: Mar 2005
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From: Earth
Rats! I figured as much. I don't remember seeing a switch, but I'll check again. Either way, it won't be a total loss since my other truck has a V8 so I can just swap it there. Back to the junkyard...
