# Analog tach for VW

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#### Marc W

##### Well-Known Member
I have a Tiny Tach which works fine. However, I can't read it when the light is bad. I like to fly at sunrise and the low sun angle makes the display unreadable. I am looking for an old style tach with a regular old style dial with a white needle that will work with a magneto or the Great Plains secondary ignition. It is a waste spark system so the tach needs to work with that. It also needs to be no larger than 2-1/4". Any suggestions for a decent tach that won't break the bank?

#### Daleandee

##### Well-Known Member
Westach makes one that will fit but depending on your limit it might be in the “break the bank” area for you.

Here’s the one I think you would need *ouch*

#### Pops

##### Well-Known Member
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They work and you can get them in blue or red . Also if you don't have an electrical can be powered by a 9 volt battery. No trouble seeing

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#### Marc W

##### Well-Known Member
I might try this one. The price is right. The red is probably easier to read. Thanks.

#### Pops

##### Well-Known Member
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The Hall Effect NPN sensor is a little large. I found a smaller one. How, I don't remember where on the internet.
Picture is of the large sensor on the mount I made for the C-85 engine.

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#### Jim Chuk

##### Well-Known Member
I have a never used VW tach. Probably sell it fairly cheap. I can get some pictures of it if you are interested. Sorry, I missed the part in your post about it needing to be 2 1/4" I think mine is larger then that. I'll take a look when I go out to the garage later. JImChuk

#### Daleandee

##### Well-Known Member
I might try this one. The price is right. The red is probably easier to read.
Please report back on what you find out. I like the look of these but some of the reviews are quite negative as to the quality.

#### Jim Chuk

I went and looked at the VW tach I have. It will fit in a 2 1/8" hole, and measures 2 1/4" across the face. It is also made to mount on top of a panel. If you want to see some pictures, I can text them to you. $25 and shipping will get it. JImChuk #### Pops ##### Well-Known Member HBA Supporter Log Member I went and looked at the VW tach I have. It will fit in a 2 1/8" hole, and measures 2 1/4" across the face. It is also made to mount on top of a panel. If you want to see some pictures, I can text them to you.$25 and shipping will get it. JImChuk
Can you give us a link ?

Dan

#### Marc W

##### Well-Known Member
Jim,

Will it work with a Slick magneto or the electronic waste spark system? The electronic ignition has two sensors and each sensor fires its own coil. If you hook the tach to one coil, it will only see two cylinders firing every 720 degrees. If it works with the mag or two coil waste spark system, I am interested.

Do you know the manufacturer and model?

#### Jim Chuk

##### Well-Known Member
Sorry for the delay in getting back to you, the tach is made to hook to a distriburor ignition. It's a cheaper aftermarket tach. I don't see a brand name on it. JImChuk

#### Marc W

##### Well-Known Member
OK, I don't think that will work with my ignition. I will pass. Thanks for checking on it.

#### PixiePilot

##### Member
Just a thought here, On my 1.7 L VW I found it a much better indicator of how hard the little iron engine is working...install an aircraft Manifold pressure gage! Run up see 29 inches, First power reduction to 25, cruise 22 inches. Want to try your hand at soaring? Back off to 19 inches and try to find lift on summer morning. I always worry my tiny RPM gage could short out and ground that ONE AND ONLY) P lead!

#### Dana

##### Super Moderator
Staff member
Westach makes one that will fit but depending on your limit it might be in the “break the bank” area for you.

Here’s the one I think you would need *ouch*
That looks like the one I had in my Fisher (half VW, Slick 4316 magneto).
they work and you can get them in blue or red . Also if you don't have an electrical can be powered by a 9 volt battery. No trouble seeing
I put one of those on my mill when I replaced the AC motor with a variable speed DC.

I always worry my tiny RPM gage could short out and ground that ONE AND ONLY) P lead!
That's why you're supposed to put a 1/4A fuse in the line...

#### Marc W

##### Well-Known Member
I never see 29 inches. Manifold pressure is about 25 inches sitting on the ground. 19 inches is wide open up over the mountain. Flatlanders!

#### TiPi

##### Well-Known Member
Log Member
That looks like the one I had in my Fisher (half VW, Slick 4316 magneto).

I put one of those on my mill when I replaced the AC motor with a variable speed DC.

That's why you're supposed to put a 1/4A fuse in the line...
not a fuse, a resistor. Run the engine and use a variable resistor (potentiometer) from the P-lead to ground, then change the setting from High to Low until the ignition on that circuit cuts out. Measure the resistance, add about 20% and round up to the nearest resistor value. Put that resistor between the P-lead and the wire going to your tacho and you will never have an ignition out from the tacho or tacho wire.
As an example, the B&S Magnetron coil will not cut out with a resistor of >70 Ohm (100 Ohm is nearest value).

#### Dana

##### Super Moderator
Staff member
not a fuse, a resistor. Run the engine and use a variable resistor (potentiometer) from the P-lead to ground, then change the setting from High to Low until the ignition on that circuit cuts out....
The one I had specified a fuse. The tach should already have a very high internal resistance.

#### Pops

##### Well-Known Member
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Another reason I like the Tiny Tack. Can't short the mag out.