mustang cluster swap into fairmont?

[paul78zephyr]

Hmm...

http://www.jason.fletcher.net/tech/tach/4cyltach.htm

OK he has no pics but I think I understand what he is doing

In section III, step 4:
"4) Locate rpm calibration resistor on circuit board"

I think that is a variable resistor. Is there one on your board?

It looks like the rest of the steps basically have you add a 100K resistor in parallel with this 'adjustable resistor'. Step 7 I think you need 1/2 the resistance of the two in parallel (original variable and new 100K) as you had with the variable resistor alone - at least thats how Im reading it.

If thats all there is to it you are home free!

Im not sure if this guys site is current or if he even maintains it anymore. I could not find an email if you wanted to contact him and the message board is dead. But his yahoo group is still there (Im a member!). Maybe you could contact him there if you have any questions.

http://autos.groups.yahoo.com/group/carbedMustang/


Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

Paul, how much do I owe you for all this work? Jeez...

well, I notice it doesn't say anything in his page about removing the (only) 62K resistor, throwing it in the wastebasket and then dumping a filter full of coffee grounds (among other things) on top of it. @#$%^&!!!

Yeah, the variable resistor is the little trimmer I mentioned. It's in series with the 62K.

Time to go wastebasket-diving. Still have 4 100K resistors left from my earlier experiment.

Seems a little shaky though... this means putting another 100K resistor in series with the 62K, albeit in parallel with the variable resistor (trimmer.) Well, it's definitely worth a try. Thanks Paul!

[paul78zephyr]

Paul, how much do I owe you for all this work?

Just let me know how you make out.

I think we both learned alot about tachs (but still there is much we dont).

Maybe we can meet at one of those Saturday eve cruises that NH Mustang and Ford club has at Home Depot 'way over east' on Rt 102 in Londonderry. But its got to be nice eve - no rain and not 900 degrees!

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[paul78zephyr]

BTW you never did tell me how you wired up the tach without the C217 connector? Did you just connect a wire directly to the 'signal' stud on the tach?

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

His page was last modified Saturday, December 15, 2001 6:16:26 PM. He has to be close to having those pictures ready by now.

It does seem pretty clear. It's job #1 tomorrow! I'll keep you posted. Thanks again, Paul!

cjl

[cleger]

BTW you never did tell me how you wired up the tach without the C217 connector? Did you just connect a wire directly to the 'signal' stud on the tach?

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

I used some bits of old coat-hanger and scotch tape.

Not really, but not much more advanced either. Just used a jumper from the + solenoid post, another one to ground, and held a meter probe against the signal stud and jammed the sharp end into the coil ground.

[cleger]

Should mention that the terminals on the tach itself are marked. There are letters B, G and C molded into the plastic by the studs. I just hooked the jumpers and held it in one hand under the hood while I worked the throttle with the other.

[paul78zephyr]

I used some bits of old coat-hanger and scotch tape.

Not really, but not much more advanced either. Just used a jumper from the + solenoid post, another one to ground, and held a meter probe against the signal stud and jammed the sharp end into the coil ground.

Very high tech!

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[paul78zephyr]

Should mention that the terminals on the tach itself are marked. There are letters B, G and C molded into the plastic by the studs.

The 6K tach housing is marked the same exact way. Could be the same plastic housing. Mine is also ink stamped with 4M12 = 12 Dec 1984.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

Very high tech!

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

Oh, you should see some of the procedures we use around here.

Maybe someday I'll show you my "breaker bar," my "bearing press" and my "filter wrench."

[cleger]

The 6K tach housing is marked the same exact way. Could be the same plastic housing. Mine is also ink stamped with 4M12 = 12 Dec 1984.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

This one is marked "9E3," I guess May 3, '79? Has a 1980 part number molded into it though.

[Fearmont]

Clegster, did you get my PM about the seats?

Phillip

[cleger]

Yes, sorry I haven't replied. Give me a minute...

Also sorry there's no resolution to report re: mustang cluster swap! I haven't had a chance to get back to it. Did install some fresh control arms and got new tires though.

Leaving for vacation Saturday, so every other spare moment has been spent trying to get the boat ready. I think I will bring the soldering iron along to Winnipesaukee so I can (hopefully) wrap-up the tach issue.

[paul78zephyr]

Yes, sorry I haven't replied. Give me a minute...

Also sorry there's no resolution to report re: mustang cluster swap! I haven't had a chance to get back to it. Did install some fresh control arms and got new tires though.

Leaving for vacation Saturday, so every other spare moment has been spent trying to get the boat ready. I think I will bring the soldering iron along to Winnipesaukee so I can (hopefully) wrap-up the tach issue.

Leave the soldering iron at home and enjoy the boat on Winnipesaukee...just let me know when you get to it.

What kind of boat? Fishing? Largemouth?


Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

Well, the way things are going, I may just need the soldering iron for the boat!

Boat is not for fishing... I'm no fisherman. It's a 17' Baja with Johnson GT150. We just use it for skiing and traveling around the lake, mostly to Weirs or someplace to eat every night.

Funny you mention fishing at the big lake... my uncles had places on the lake for years & years, even before I was born. They were huge sportsmen. Hunting, fishing... go over to my uncle Teddy's house, and there were duck decoys in the barn etc.

Anyway, I've been vactioning there most of my life, and in all the years I was up there either fishing or watching my uncles fish, trolling for lakers, etc, I never once saw any of them (there were 7 brothers) catch *anything*. Nothing but kivvers and hornpout.

[paul78zephyr]

It's a 17' Baja with Johnson GT150. We just use it for skiing and traveling around the lake, mostly to Weirs or someplace to eat every night.

Like this one (was in NH!)?
http://nh.craigslist.org/boa/376333019.html

Sounds like you are on the lake alot. Thats great. Its nice to have another hobby beside cars. I used to go out to Quabbin reservoir and rent a small fishing boat and motor (10hp!). Used to be you could get a boat, motor, and tank of gas (8 gal) for the entire day for around $30. I never caught much their either (some bass and pickerel) but I mainly went for the solitude and beauty of the place - especially in the early fall.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

Like this one (was in NH!)?
http://nh.craigslist.org/boa/376333019.html

Sounds like you are on the lake alot. Thats great. Its nice to have another hobby beside cars. I used to go out to Quabbin reservoir and rent a small fishing boat and motor (10hp!). Used to be you could get a boat, motor, and tank of gas (8 gal) for the entire day for around $30. I never caught much their either (some bass and pickerel) but I mainly went for the solitude and beauty of the place - especially in the early fall.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

My boat is a little different. It's a "Sport 170." Balsa wood frame, nothing but seats, controls, and motor. Light and fast, it's the Fairmont of boats. Pretty much just like this one:

http://www.angelfire.com/mi/pyrotechnician/baja.html

...except mine is blue and the motor is white, and I have a hydraulic jackplate and custom Morse controls. Does about 60 with a 22 Raker, which is fast for a boat this size. Probably get another 5 mph out of it with a taller prop, but we like to ski. GT150 is about a 2.5 liter (I think) V6, and will burn an easy 20 gallons a day without even trying that hard. Three 2V carbs.

First house I bought years ago was on a small lake. One of my neighbors had an aluminum fish/ski-type boat with a pair of 20 horse outboards that he used to take to Quabbin. I think the deal then was as long as he pulled of one of his props, they'd let him in with it. But back home, he used to pull his kids behind it on skis!

[cleger]

Here we go. That's me looking confused (again) on the way back into the dock last summer.

Fairmont content: think I might have compromised my starter solenoid trying to crank a bad reman Napa starter, so I'm going to swap it out today.

Reminds me... TWO (!!!) bad starters from Napa! First one worked great in the morning, but would get harder to crank after driving for a while and things heated up. Took it back for a replacement (miraculously still had the receipt) and asked the guys at the counter if they got a lot of them back. Both responded loudly in unison "nope!"

Replacement starter wouldn't kick or spin whether in the car or on the ground with cables and two different known-good batteries. Took it back. Napa guys swore nothing like this had ever happened before. Thanks guys. Another half-hour on the ground, and an hour's worth of driving because of your "confidence" in your starters. No more Napa for me.

[paul78zephyr]

Here we go. That's me looking confused (again) on the way back into the dock last summer.

Fairmont content: think I might have compromised my starter solenoid trying to crank a bad reman Napa starter, so I'm going to swap it out today.

Reminds me... TWO (!!!) bad starters from Napa! First one worked great in the morning, but would get harder to crank after driving for a while and things heated up. Took it back for a replacement (miraculously still had the receipt) and asked the guys at the counter if they got a lot of them back. Both responded loudly in unison "nope!"

Replacement starter wouldn't kick or spin whether in the car or on the ground with cables and two different known-good batteries. Took it back. Napa guys swore nothing like this had ever happened before. Thanks guys. Another half-hour on the ground, and an hour's worth of driving because of your "confidence" in your starters. No more Napa for me.

Nice boat! Is that on Winnipesaukee?

Im pretty sure HP limit on Quabbin is 20HP.

Im suprised you are having trouble with the NAPA starters. NAPA used to be quite good stuff, especially their electrical stuff (alts, starters, ignition, etc). You know you can ask the parts stores to bench test the starter before you buy it. I always check a new starter on the ground with jumper cables before spending X hours cussing and getting it in.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

[cleger]

Nice boat! Is that on Winnipesaukee?

Yeah, that's "Dale Cove" behind Stonedam Island.

Im pretty sure HP limit on Quabbin is 20HP.

That's what I remember. That's why the guy could get away with running a single 20.

Im suprised you are having trouble with the NAPA starters. NAPA used to be quite good stuff, especially their electrical stuff (alts, starters, ignition, etc). You know you can ask the parts stores to bench test the starter before you buy it. I always check a new starter on the ground with jumper cables before spending X hours cussing and getting it in.

Paul
1978 Mercury Zephyr - The FIRST FourEyed Fox

Yeah, I was a little surprised too. The first one worked, but performance degraded as things got hot. Second one was dead, dead, dead.

Got my money back and went to Advance Auto Parts. Finally tested that one in the parking lot (brought my cables and battery with me. You could say I was a little frustrated at this point.) Sucks because Napa is the nearest store to me, about 5 miles away. I do prefer Sanel's or Robbins though. They're both "real" parts stores with multiple locations and quite knowledgeable staff. Nearest Sanel's is 10 miles, in Weare.

Anyway, for all I know, all the chains have their starters rebuilt in the same Honduran "factory." This one seems to be working well though. Third time's the charm, I guess.

[cleger]

OK guys, here's the scoop:

I've successfully modified & "calibrated" the 8K 4-cyl tach in my '79 4-cyl cluster for use with my 302.

Picked up a second cluster (+ the whole dash harness so I got a spare cluster connector) and used the tach in that cluster as a reference. It is a 4-6-8 tach, and all three circuits were present.

As you may recall, the 4-cyl 8K tach had only a single leg of the three-way switchable engine-selector circuits present on its board. This leg consisted of a single 62K ohm .25W resistor, plus a little 0-100K trimmer pot in series.

In the page at the link Paul posted in reply #51 above, the author wrote instructions to the effect that one should solder a 100K resistor across the trimmer terminals. I thought about this some, and the more I thought, it didn't seem right. Since the trimmer goes from 0-100K (at the time, I didn't know how high it would go, but figured it was wide-open/0K at one end of its range) running a 100K resistor in parallel with the trimmer would only decrease the upper end of the trimmer's resistance, but it would still drop to zero at the other end of its range.

Anyhow, turned out I was right, so we can all disregard the advice on that page Paul posted (but is not responsible for!) I tried adding the 100K resistor across the trimmer, but still couldn't get the resistance low enough. Almost, but not quite. The 8K tach would read about 1100 rpm at idle, with the trimmer backed all the way off, while the factory 4-6-8 tach would read 850 or so. Zero ohms is still zero ohms.

So, what I did instead was go back and remove the 100K resistor I had added, and replace the factory 62K resistor with a 22K I had laying around. This change, in combination with a little adjusment to the trimmer, and the tach was dialed right in. I think a 10K resistor might have been better, but with a 0-100K sweep on the trimmer, there's plenty of adjustability... a 33K, or even NO resistor, probably would have worked as well. if you figure it was set at around 50K at the factory for a total of about 112K with the resistor (for a 4-cyl car) then setting it at 34K to work with the 22K resistor for a total of 66K in an 8-cyl car still leaves the trimmer near enough to its midpoint to allow plenty of adjustability.

Now, I have to admit, I didn't take all the readings & record everything like I promised. Sorry, I have so many things going on that once I got it working, I put everything back together and buttoned it all up. But here's the thing - if you have a meter, and you want to tackle this, all you need to do is take a reading across BOTH the trimmer (at the factory setting) AND the 62K resistor, record that number, then replace the 62K with a 22K resistor, put your meter back on the traces around the trimmer and your new 22K resistor and use the trimmer to HALVE the old value you recorded. This should leave you pretty much dead-on when you put the tach back in the car.

The only reason this didn't work for me the first time was that I assumed you'd double the resistance value to accomodate for the 2X igniton pulses from the V8 versus the 4-cyl engine. I even had the 22K resistors but didn't try using them. Turns out, you really want 0.5X. Why tachometer magic works this way is beyond me, but there it is.

Hopefully this will help the next guy who wants to put an 8K tach in his V8 car. The resistors cost pennies and are in the drawer at your local Radio Shack. At the very least, I can assure all of you that a 22K resistor in place of the 62K will work perfectly. The sweep of the 8K 4-cyl tach and the selectable 4-6-8 tach matched each other exactly, as far as I could tell, from idle up through 3500-4000 rpm.

[cleger]

Thought I'd mention that I'm getting an indicated ~3200 RPM at 60 mph in 4th (1:1 in a T-5) with 4.10:1 gears.

By my reckoning, actual should be 3179 RPM. The 21 RPM difference isn't even enough to account for parallax, so the 22K resistor is clearly a good way to go. Start scrounging for those 8K tachs, folks.

[Stormin' Norman]

I was cruising the WWW, looking for gauge faces for a redo of my 1979 Squire dash. I found some downloadable gauge JPGS in black or in white backgrounds and an article on the Cougar model limitations. You guys did a great thread on that, BTW. Thanks.

Here's the Cougar 4 to 6/8 tach trilogy:
http://www.coolcats.net/tech/advanced/4to8tach.html

Which comes from this TECH Article List:
http://www.coolcats.net/tech/advanced/

Here's the Gauge face How to:
http://www.coolcats.net/tech/advanced/140speedo.html

And the gauge face pics:
http://www.coolcats.net/media/index.html

[48fordnut]

I am installing a 84 mustang 6 cyl, no tach problem,inst cluster into my 80 fairmont. I need the connector that you are talking about. In my area all of the early 4 eyes are gone as well as the f/z. help.

[48fordnut]

I've heard this has been done. I think there is a second connector which needs to be harvested from a donor vehicle. I'll have to root around in my old files to see if I copied and pasted a write up on how a guy did this.

Dean T

Dean, do you have a second connector. like the one being reeferenced? lmk, jim.