So I have a 930 Tach, and every time you rolled it around it would rattle. I figured that someone dropped a bulb in it, but before I did something with itI needed to find out why it rattled so.

So let the autopsy begin.

930 Tach - so what makes these so damn expensive That little 1 bar boost gauge hosed in the face.

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Tools of the trade - custom made for this job.

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Opens gauge bezels like a can opener.

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Just work your way around, at least 3/4 of the way.

All opened up

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Flip it over remove three screws and one nut.

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And removed from the can

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More Detail just for you Tim

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Interior of the can

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And now what was rattling around inside the tach.










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I was right

Can't wait to see what happens to this now

It's amazing how VDO stuck with their same board design of over 20 years. Instead of spending a few bucks by doing a simple revision of the circuit board so it profiles around the boost gauge, they just used what they had and crammed it all together.

Notice how they had to tilt the main board so it fits around the boost motor.

So how hard is it to substitute in a 914 gas gauge for the boost gauge.

Mechanically, I would just reuse the boost motor as the fuel gauge motor. You may need to change the resistor, but it's minor work. Re-stenciling the face plate would be the bigger issue.

The needle for the boost gauge isn't in its proper resting point, is your boost gauge broken? There should be a hair spring attached to the needle shaft so the needle returns back to zero.

It's not just the 930 tach. Any Porsche part that starts with 930 is expensive.

I recently saw a valuation of the 1986 930 which puts the value of the car between $75k and $115k.

Well, here is the real skinny on this.

The boost gauge portion is not broke, it goes full right with out a resistance source. That is a big plus. So it is working as intended.

930 parts carry a cult status with them. I completely understand why, but just saying for what it is it is not that big of a deal. Certainly not worth the $$$.$$ being offered on Ebay for

Yes you can add a fuel gauge movement to the tach with the help of some friends. You can do it with a stock face plate and some carful drilling. and then a couple of tick marks, a vinyl stencil would most likely do the trick. and then a bit of 1 shot and a nice brush. Or 1 shot and an airbrush. Add a small spot for the low fuel warning light to go, and well you got a working gauge. And a very nice trick combo gauge.

Mark what are you running that you need more gauges?
Speedo
Tach - add 1
and a Quad or Triple gauge.
With the Quad you can have 5 (other) gauges, that is a lot of gauges.

My 914-6
Oil temp / Pressure, and fuel.
Guess I could add cylinder head temp or two for both banks and move the fuel over to the Tach. Quad is easily made via a 924 combo gauge.

My EG build
Oil Presuure
Oil Temp
Water Temp
Fuel
? - but if I use the 930 tach, then I would keep it a 930 tach and add positive pressure to the intake side.

Ooooo Stephen, that would look very nice in my Getty dash for Grey Matter.

Just sayin'
Tom

I was just thinking of adding the gas gauge as an alternative to using a triple gauge. Something different.

But if people are getting a grand for these gauges, I should probably hold off for now.

I could do that, with some motivation, that is what made me get it out and see what was going on. with the rattle.

I'll PM you.

So now since Mark posed the question.

Yes you can put a stock fuel gauge into a 914 Tach, but a few items will have to change.

So I did a bit of quick disassembly tonight. And found this to be true.

Movements will work, the fuel gauge would read full on the left and empty on the right. You would have to add a tube for the low fuel warning light. There is enough room to do it.

Depending on the tach, the high beam indicator might need to be moved. On the back a hole would need to be filled. Face would need to be modified for the gauge movement and a proper brace made. Wiring for the power and ground would need to be spliced. Face would need to have the marks redone so the fuel gauge and the tach, moved ho beam indicator and others would look proper and factorish. And last but not least all re-assembled.

So here is what we are trying to stuff into a 914 Tach.

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The backsides of the 930 Boost gauge and the 914 fuel gauge, Like Tim said very similar.

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And now for the old man photoshop methods

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I might need to start making the kit to do this.

Note this Tach face has the combined turn singles, and the high beam indicator out of the way. Prefer these as hopefully I am still smart enough to know which direction I have left my turn signal on.

Stephen - is there any way to flip the gas gauge 180 degrees.

You might try using a 911 fuel gauge, which reads the other way, the same as the 930 boost gauge. They're easy to come by and cheap since every 911 had one. The marks aren't a match to the linearity of the 914 gauge, but you're going to have to Photoshop them anyway, and the gauge does also have a warning light.

Best solution would be to leave the gauge as is and install a turbocharged 930 into the teener.... thats what i would do......

Mark, are you talking reverse rotation on the gauge? Or have the needle facing down to the bottom? Like it does in a stock gauge. The 2nd option would be no, as it would compete for real estate with the tach movements. And updating the tach movements to a smaller unit, causes some other issues that might not be favorable. The two needles could cross, and get locked like an old typewriter.

The other item, I have been thinking about reverse rotation and have not found my complete answer. Of course I might just have to test it out. It is a DC motor of sorts, so maybe just reversing the polarity would do it. But I doubt it will be that easy, otherwise every one would be doing it.

I love the type writer analogy! Perhaps you could stagger the needles? Have the fuel gauge needle hugging the face plate, while the updated tach needle hanging out further, closer to the glass lens?

Not a easy task with this style motor. They have a hair spring attached to the shaft, you would need to flip the spring. Then, the gauge motors' case is grounded, you would need to remove the motor from its case and move some wires around. These wires are super thin, wouldn't be easy. I like Larry's idea with using a cheap 911 gauge motor.

Just ordered the film thank you Bob for the suggestion. Will give it a try and se how it does. Bob and I have exchanged several e-mails and we will give his method a try. As Bob says "Been dicking with this stuff since 1974" I'll sage wisdom. The thread that made me reach out to Bob can be found here

First Project per Mark's request a 911 fuel gauge in a 914 Tach, nice and flat, and should put it to a good test.

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I can add more hash marks or ticks in-between the numbers to make it closer to the Porsche / VDO tach of the time period. Not bad for a few minutes and not using a scanned face. That will be next, when day light is not burning.

Ran a test print, I'll add it to a piece of AL and cut it out and see if all the stuff is in the right spots adjust and finish the design up. then off to get them cut, with a bunch of other items.

So yes Tim you will be getting a shipment soon.

Sounds good! Could you also do a face overlay with a voltmeter vs the fuel gauge?
I looked into the silk screening process and it did make my head spin, this is why I stuck with gauge lighting.

Yes that is not an issue, I can pretty much do what every you want to put in there. As long as it comes in a 90 degree sweep, even 120 would fit, 180 degree sweeps just won't cut it.