: '91 F-150 XLT Tachometer



Eddie
12-29-2013, 11:21 AM
I would like to get the tach working.

Truck originally came with 4.9L EFI gasser and XLT-package, which included a tachometer. That engine kinda blew up, and another I-6 just sorta appeared in there one day, honest!

'97 Dodge 6BT, with an OE sensor (proximity sensor?) mounted such that it can read off two slots cut into the balancer's periphery.

Anybody have a idea how to mate the Ford tach with a Dodge/Cummins tach sensor? (Boy, that last reads like something that shoulda "...stayed in Vegas.")

BTW, that Ford tach goes to 6,000 RPM, a feature which I'm sure I'll use every day!

Eddie

69rambler
12-29-2013, 09:11 PM
I've done it two ways- I've plugged in a V8 tach and used a flywheel or machined balancer with a dakota digital tach adapter kit or I've plugged in a diesel tach and used the 7.3 pickup with 36 notches milled into the balancer.

The gauge clusters are all the same- The Ford tachs themselves are self contained and swap out in a couple minutes.

I would caution that the last shipment of Dakota tach adapters I got in (last month) were much lower quality than the stuff I've got from them in the past. Instead of a VDO sensor they sent China crap. The body threads were oversized and the sensors were not as sensitive.

dieseldude
12-29-2013, 11:06 PM
On my Bronco tach I used the Dakota digital adapter and signal from the alternator.
I added the signal wire to the alternator myself.

lawnboy
12-29-2013, 11:17 PM
I added the signal wire to the alternator myself. could you explane how this is done.

dieseldude
12-29-2013, 11:25 PM
http://www.4btswaps.com/forum/showthread.php?27204-Adding-a-quot-w-quot-terminal-to-a-2nd-gen-dodge-alternator

brobrad
12-30-2013, 05:18 AM
I used my tach sensor off of my 4.6 and a town wheel from autoworld Montana. I had to fab a braćket but it works great.

Eddie
12-30-2013, 10:42 AM
WOW!

Looks as though I've got of places I can go...THANX, ALL!

1. Were I to use the 4.6 V-8 (I'm assuming the gasoline 4.6) scheme, what is a "town wheel"? This one would seem to be easier from a parts availability standpoint; 4.6s are everywhere.

2. I read though the alt hook-up link--would the same procedure be used with my OE (though rebuilt) '91 Ford alt (which uses the OE Cummins pulley)?

Eddie

Eddie
12-30-2013, 11:14 AM
I've done it two ways- I've plugged in a V8 tach and used a flywheel or machined balancer with a dakota digital tach adapter kit...

V8 tach--I am assuming (yeah, yeah, "assuming", I know):
a., the V8 tach came from the '87-'91 series of F-trucks, and:
b., the tach cares not if it came from a gas or diesel F.


...flywheel or machined balancer...
How many teeth?

THANX!

Eddie

fte
12-30-2013, 11:36 AM
I am using a 2 wire ABS sensor mounted to the front of my motor (Kubota V2203) reading 2 notches made in the front pulley. One wire to the signal terminal on the back of the tach, the other to 12v KO. My Ranger had a 4cyl so 2 notches are required. You will need 3 for the 6cly tach.

69rambler
12-31-2013, 07:49 PM
V8 tach--I am assuming (yeah, yeah, "assuming", I know):
a., the V8 tach came from the '87-'91 series of F-trucks, and:
b., the tach cares not if it came from a gas or diesel F.


How many teeth?
THANX!

Eddie


The Diesel tach is completely different from the gas tachs. The diesel tach reads the signal output from the 7.3 tach sensor. The 7.3 tach sensor (IIRC) reads the 72 tooth IP gear. If you're reading off the crank it's spinning double IP speed so you 1/2 the 72 teeth for 36. I could be wrong on that tooth count, so don't take it as gospel.

I use a 98-02 5.9 Dodge balancer ($181 from Cummins dealer). I bolt it on my Mori, dial in center, touch off and run a program wrote to plunge an endmill into the circumference to generate the appropriate "scallops" for the sensor to read. It works pretty good. If you don't have a VMC to play with a BP with a rotab or even just a DRO and some CAD software can generate the point data.

The gas tach needs the Dakota sensor to convert the signal into the proper square wave the ignition system was putting out. The Dakota box is somewhat limited on it's range and needs to see a minimum number of teeth on whatever's spinning to be able to divide the pulses. I would want 40+ teeth for a V8 tach. The flywheel teeth work well if you have a breadvan adapter.