tach.question
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More Turbo
Joined: Jun 2008
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From: coe hill on.can.
tach.question
my truck is a 1984 f150 300 six . my question is i have a instrument panel out of a 1984 f150 that had a 351w motor in with a tach. will it work in my 84 6cy that did not have a tach? would i have to change any thing or would it have any wiring allready there that it needs ? would it register right? thanks i need any help i can get.
Postmaster
Joined: Apr 2003
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From: Harrisburg, NE
i dont see how it would read right, when i went from a 6 to an 8 in my capri I had to turn a little screw over to"8", and its been so long since i have had the cluster out of my bronco that i really don't remember. could you let us know if it reads right or not?
Fleet Owner
Joined: May 2009
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From: Gilbert, PA
It will read right. the only difference is between a 80 tach and a 81-86 tach. And there is no adjustments. It rears off the coil wire so it can tell how often if fires. There is no adjustments on any aftermarket tach i have ever owned either.
Cargo Master
Joined: Mar 2008
Posts: 2,573
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From: Washington
Tach Info
Here is a photo of the back side the tach. 81-86 F150
B = 12 volt power for tach
G = tach ground
C= is the connection to the NEG side of the coil
8= this will need to be grounded IF you have a V8 or it will read wrong
The grounding for connection "8" (lower left in photo) is done on the engine side of the wiring harness, which is why the instrument clusters will swap between a V8 and a inline 6.
Below in a photo of a engine wiring harnes for a 4.9 without the ground wire.
Notice there are 2 wires on the truck side of the "TACH" plug and only 1 on the engine side of the plug. That is how you can tell this is a harness for a 6 cyl engine. A V8 engine harness would have 2 wires on each side of the plug, the second wire would be the ground for the "8" connection on the tach.
Below is a photo of the harness in the truck, the tach plug is the one in the center with the single green wire on the engine side.
have fun.... Jim
B = 12 volt power for tach
G = tach ground
C= is the connection to the NEG side of the coil
8= this will need to be grounded IF you have a V8 or it will read wrong
The grounding for connection "8" (lower left in photo) is done on the engine side of the wiring harness, which is why the instrument clusters will swap between a V8 and a inline 6.
Below in a photo of a engine wiring harnes for a 4.9 without the ground wire.
Notice there are 2 wires on the truck side of the "TACH" plug and only 1 on the engine side of the plug. That is how you can tell this is a harness for a 6 cyl engine. A V8 engine harness would have 2 wires on each side of the plug, the second wire would be the ground for the "8" connection on the tach.
Below is a photo of the harness in the truck, the tach plug is the one in the center with the single green wire on the engine side.
have fun.... Jim
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
Just to clarify, the tach itself is the same, 1980-1986, and so are the gauges, and speedometer head.
It's the printed circut on the back of the cluster thats different between 1980 and 1981 through 1986.
1980 Cluster Printed circuts are marked begining with E0TF, color coded Green.
1981-1986 Cluster Printed circuts are marked begining with E1TF, color coded Red.
It's the printed circut on the back of the cluster thats different between 1980 and 1981 through 1986.
1980 Cluster Printed circuts are marked begining with E0TF, color coded Green.
1981-1986 Cluster Printed circuts are marked begining with E1TF, color coded Red.
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Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
my truck is a 1984 f150 300 six . my question is i have a instrument panel out of a 1984 f150 that had a 351w motor in with a tach. will it work in my 84 6cy that did not have a tach? would i have to change any thing or would it have any wiring allready there that it needs ? would it register right? thanks i need any help i can get.
If it's got IDIOT LAMPS, you will have to swap the entire underdash harness and the altenator harness to make it work. This is because the ammeter circuts are wired drasticly different to idiot lamps. Not too hard to switch out, just time consuming, if you have the harness out of the other 1984 to work with.
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Thread Starter
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More Turbo
Joined: Jun 2008
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From: coe hill on.can.
thanks for all the info . as i said earlier waiting for dry days as no garage .both panels have full gauges no idiot lights . so it sounds like it should be ok. thanks again p.r douglas both from 84 f150s
Last edited by douglpr42; Aug 30, 2009 at 03:57 PM. Reason: left out info
Postmaster
Joined: Apr 2003
Posts: 2,703
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From: Harrisburg, NE
[QUOTE=JimsRebel;7883436]
B = 12 volt power for tach
G = tach ground
C= is the connection to the NEG side of the coil
8= this will need to be grounded IF you have a V8 or it will read wrong
The grounding for connection "8" (lower left in photo) is done on the engine side of the wiring harness, which is why the instrument clusters will swap between a V8 and a inline 6.
[QUOTE]
this answers what i was wondering, cause like i said, on my 84 capri the front of the tach there is a little hole, to which inside is a little switch you turn with a standard screwdriver to either 4,6,or 8. but this makes sense since pickups didn't come with 4 bangers.
and on every aftermaket tach i have seen there has been a switch to go from 4,6,or 8 as well as a way to zero the tach.
B = 12 volt power for tach
G = tach ground
C= is the connection to the NEG side of the coil
8= this will need to be grounded IF you have a V8 or it will read wrong
The grounding for connection "8" (lower left in photo) is done on the engine side of the wiring harness, which is why the instrument clusters will swap between a V8 and a inline 6.
[QUOTE]
this answers what i was wondering, cause like i said, on my 84 capri the front of the tach there is a little hole, to which inside is a little switch you turn with a standard screwdriver to either 4,6,or 8. but this makes sense since pickups didn't come with 4 bangers.
and on every aftermaket tach i have seen there has been a switch to go from 4,6,or 8 as well as a way to zero the tach.
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