Speedo and tach...

[Kimi]

I'm new on this Chevy side, but have been reading the topics here.

 

The situation is that I have a 240Z -72 with a Ford 260 and a Chevy Camaro T5 gearbox. So this one is a real hybrid

Problem no.1 is the speedo cable. Where can I buy a speedo cable that fits between the

240Z speedo and the T5 gearbox? Or do I have to "build" one?

Problem no.2 is the tach. Hoew can make it working properly? Now it works, but reads wrong

becouse of the V8 swap.

 

Kimi

[Mike C]

Both of these are covered in the JTR manual. You remove the tach and turn a calibration screw in the back and Stealth Conversions sells a speedo cable. Interesting combination you've got. The Chevy V8 T5 is usually more $ than the Ford so it usually goes the other way!

[Kimi]

Thanks Mike C

 

The problem with a Ford T5 was that I did not find one here in Finland. And a friend had this Chevy T5 so I thought that why not. And the combination works well. Only thing that was a bit difficult was to find a good clutch to this combination, but I used one from a Pontiac Transporter and it works well

[Kimi]

I've tried to reach the Stealth conversions / JTR by e-mail and fax but they have not answered. I did order the speedo cable and am wondering why they haven't contacted me

 

Do you guys know anybody at the JTR so I could contact directly?

[Kimi]

They answered to my mail today from JTR, so the situation is under controll

[Guest TheRawNakedPowerOfTheRoad]

DISCLAIMER: I have querried and read what I think to be everything, and haven't found this specific issue discussed, so I hope this isn't redundant. Also, I realize this is the Chevy Forum, but nobody on the Ford side has posted about this, and you came close over here, especially with Mike C.'s reply below....and, some of you have Ford experience to boot.

 

1. Can the stock tachometer be calibrated/adjusted (capable of) for connection/metering with the Ford V8?

 

I've got a '73 240Z, with a 1990 Ford 5.0L High Output motor; and MSD ignition (I don't have the model or part number). It's roadworthy, but I'm still connecting the gauges.

___ I've been working with/consulting a shop here in San Diego: "Speedo-Tach", and as they are not fluent in Z, they say they can't tell until they look inside the tachometer. Motorsport's Technical Support guys tell me that folks do it with the Chevy engines, but he can't confirm for the Ford. (To give you all the info: He also said I'd need the Ballast Resistor...which I no longer have. My mechanic [who did the conversion] disagrees with the Ballast Resistor need)

 

2. If I go ahead and wire it up, I'll try the calibration screw. However, does anyone have knowledge that this will work (from experience)? I don't know if Mike C. was sure, or if he saw the screw and speculated?? I'm wondering if the amount of adjustment needed will be in the range of the screw?

 

3. So I don't waste your time, I did get this wise response on ClassicZCar.com, but there are still holes in the blueprint, so I do seek more/confirmation:

>>>The Ballast resistor in the Z ignition circuit was only used to reduce the voltage from 12v to 6v in order to avoid burning out the points. Once you remove the points, there is no need to reduce the voltage, and in fact may cause you problems with the electronic ignition.

 

The "stock" tach in a 240 (4 wire) uses a loop of wire coming from the ignition to the coil to sense the current spikes going to the coil. This loop of wire comprises TWO of the FOUR wires going to the tach connector. The other two wires are to power the tach.

 

Now it ~may~ be possible for the tach to require the 6v voltage current through the coil but since it isn't part of the power circuitry going to it, I doubt it. The tach's power circuitry in fact, isn't even on when you're starting the car, it's only when the key is in RUN mode.

 

Now, since the tach is sensing current spikes, presumably there is some sort of counter that divides by 6 in it's circuitry, and that may be what they need to look at in order to determine what component needs to be changed to allow it to divide by 8. Otherwise, the stock tach would read a full third higher with an 8 cylinder engine. (i.e. at 600 v8 rpm it would read 800, therefore at 3000 v8 rpm : 4000)

 

Since the circuitry for the engine won't be that much different between Chevy and Ford, why not ask what they do for the Chevy and try that?<<<< End of his reply<<<<

 

_ I'm not going to break a leg to use the stock tach, but do prefer to. Your help is appreciated. Good day.

[Mike kZ]

A stock tach should work on a Ford engine, but you need a 280Z tach. JTR suggests sticking the inners of a 280Z tach into the housing of a 240Z tach so everything fits, and looks stock.

[VinhZXT]

A stock tach should work on a Ford engine, but you need a 280Z tach. JTR suggests sticking the inners of a 280Z tach into the housing of a 240Z tach so everything fits, and looks stock.

 

Awhile back I was trying to hook up my friend's hybrid Z. He got a 350 in an earlier 260z or possibly 240z. In either case I followed JTR direction and was very confuse. Why would you want to stick the inners of the 280Z tach inside the 240z housing? Why not just use the whole 280z tach and housing? Can you someone explain this? I might have to go back and check this out again so I can get it working for my friend. Thanks for any help.

[Guest TheRawNakedPowerOfTheRoad]

So, Mike, you are telling me, for sure, that the 240Z tach will not work (and the 280Z will)?

[Mike kZ]

I've never done this swap, but that's what JTR says.