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> GT Tachometer conversion with 10K upm scale, Bosch core, small batch being made
Retroracer
post Oct 26 2019, 11:00 PM
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SO there are some threads floating around which detail the conversion of a stock 914 VDO tachometer to use a modern Bosch drive core. Improved ballistics and more modern internals are the main motivation for this; the VDO cores tend to overshoot as they age.

I modified one to match to a 10,000 upm GT style fascia - sourced from Germany - and fitted it to my car. The core needs to be calibrated to the motor type (4 or 6 cylinders) but once done works with a wide range of inputs (Bosch CDI, MSD, etc) and is a talking point to anyone remotely familiar with the details of racing Porsches. The original 10K tach units appear for sale occasionally - but are fairly pricey. Hence the motivation to make a more accessible solution.

Here is mine completed:

Attached Image

and in the car:

Attached Image

Since completing mine, I have been accumulating a few 914 tach cores - dating from 69 to 73 - and am in the process of stripping and cleaning these in prepraration for building them up as 10K replica units. Once finished, these will have Bosch cores, refreshed needles, 10K fascias sourced from Germany, two L/R indicator lights and a main beam indicator. They will be calibrated for a 6 cylinder engine.

When complete and tested, these will be going up for sale. I need to figure out a reasonable price, but am posting this to gauge interest from 914world folks. Am guessing I can get some attention from the 911 boys over on the bird, if I get no interest here; but I'd rather see these being front and center in a 914!

If you have an interest in purchasing one, or have questions, then PM me and let me know. At this stage I can also calibrate them for different motors - a V8 for instance. I'm only doing a few of these, just so you know.

- Tony





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mb911
post Oct 27 2019, 05:48 AM
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Sounds very interesting. I know a few people that would be interested
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rgalla9146
post Oct 27 2019, 06:20 AM
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I'm in on the 10k tach
Is a GT fuel gauge possible ?
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roblav1
post Oct 27 2019, 06:33 AM
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I'm interested too.
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rothaus
post Oct 27 2019, 06:46 AM
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Could you make it so that the numbers and marking horizontal, like in this picture.

(IMG:http://www.914world.com/bbs2/uploads_offsite/rennlist.com-12404-1572180394.1.jpg)
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Retroracer
post Oct 27 2019, 08:05 AM
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QUOTE(rothaus @ Oct 27 2019, 05:46 AM) *

Could you make it so that the numbers and marking horizontal, like in this picture.

(IMG:http://www.914world.com/bbs2/uploads_offsite/rennlist.com-12404-1572180394.1.jpg)


Not exactly like the unit depicted, but yes that style is available. It will have a chrome dot needle for sure. I found with mine and a smaller MOMO wheel, the top of the wheel obscures the upper part of the tach, so the rotation on mine helps keep the usable rev range visible without craning my neck...!

I'm planning to make these all identical as much as possible - if you want something different/unique, PM me and we can discuss

- Tony
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Retroracer
post Oct 27 2019, 08:08 AM
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QUOTE(rgalla9146 @ Oct 27 2019, 05:20 AM) *

I'm in on the 10k tach
Is a GT fuel gauge possible ?


This will be just a few 10K tachometers.

- Tony
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jwinner
post Oct 27 2019, 07:23 PM
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QUOTE(Retroracer @ Oct 27 2019, 12:00 AM) *

SO there are some threads floating around which detail the conversion of a stock 914 VDO tachometer to use a modern Bosch drive core. Improved ballistics and more modern internals are the main motivation for this; the VDO cores tend to overshoot as they age.

I modified one to match to a 10,000 upm GT style fascia - sourced from Germany - and fitted it to my car. The core needs to be calibrated to the motor type (4 or 6 cylinders) but once done works with a wide range of inputs (Bosch CDI, MSD, etc) and is a talking point to anyone remotely familiar with the details of racing Porsches. The original 10K tach units appear for sale occasionally - but are fairly pricey. Hence the motivation to make a more accessible solution.

Here is mine completed:

Attached Image

and in the car:

Attached Image

Since completing mine, I have been accumulating a few 914 tach cores - dating from 69 to 73 - and am in the process of stripping and cleaning these in prepraration for building them up as 10K replica units. Once finished, these will have Bosch cores, refreshed needles, 10K fascias sourced from Germany, two L/R indicator lights and a main beam indicator. They will be calibrated for a 6 cylinder engine.

When complete and tested, these will be going up for sale. I need to figure out a reasonable price, but am posting this to gauge interest from 914world folks. Am guessing I can get some attention from the 911 boys over on the bird, if I get no interest here; but I'd rather see these being front and center in a 914!

If you have an interest in purchasing one, or have questions, then PM me and let me know. At this stage I can also calibrate them for different motors - a V8 for instance. I'm only doing a few of these, just so you know.

- Tony


Hi Tony,

Ben McFarland (mb911) just completed my 2.7 -6 Conversion and I would love to have one of these 10K tachometers. I like that horizontal style that somebody posted a picture of, looks like something out of a 917. Please keep me in mind if you have one available. Thank you, James Winner.

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gereed75
post Oct 27 2019, 07:39 PM
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Interested Thanks
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Retroracer
post Nov 20 2019, 09:37 PM
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Update for those who expressed interest: so the tach fascias from Germany just cleared customs - arrived yesterday. Here's how the "clocked" version looks:

Attached Image

The fascias are super high quality pieces. I now have all the parts in house, I just need to the PCB mods, calibrate and test all 3 units - then zip them up.

- Tony
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pete000
post Nov 20 2019, 10:04 PM
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I had a 911T Tech converted to 10K by North Hollywood Speedometer for my 1970 914-6 It came out great, but it would not read the correct RPM. It was off by about 2000 rpms high. They did some reprogramming and then it would not work at all. Ended up selling it to a guy with an early 911 and he seemed to have no issues. I did not want to reface my factory six tach. Not sure what goes on inside as to compatibility, but it would be so nice to have one that would work.

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mepstein
post Nov 20 2019, 10:20 PM
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QUOTE(pete000 @ Nov 20 2019, 11:04 PM) *

I had a 911T Tech converted to 10K by North Hollywood Speedometer for my 1970 914-6 It came out great, but it would not read the correct RPM. It was off by about 2000 rpms high. They did some reprogramming and then it would not work at all. Ended up selling it to a guy with an early 911 and he seemed to have no issues. I did not want to reface my factory six tach. Not sure what goes on inside as to compatibility, but it would be so nice to have one that would work.

@pete000
http://www.ashlocktech.com/


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pete000
post Nov 26 2019, 08:14 PM
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Wow, that's cool. I might just have to build another 10K tach and try this solution. Thanks for sharing
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targa72e
post Nov 26 2019, 10:18 PM
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I am using one of these tach adapts with my -6 conversion. Have 911 3 pin CD box and use with stock -4 tach. works great.

john
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914dave
post Nov 27 2019, 05:31 AM
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I’m interested
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rgalla9146
post Nov 27 2019, 06:47 AM
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I'm interested. 4cyl. tach to 6cyl, 6 pin CD 10k Yes.
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Retroracer
post Nov 30 2019, 04:28 PM
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Progress made over the long weekend, for those interested. The two "regular" 10K units are ready for test and final clean and assembly. Still waiting on a component for the "clocked" version.

Creating these things is a nice multi-discipllne challenge - electronics, metal bending / persuasion, machining, prep & painting, etc. Should be done and available before Christmas!

Attached Image

- Tony
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Retroracer
post Dec 19 2019, 09:50 PM
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Now finished:

1969:
Attached Image Attached Image



1972:
Attached Image Attached Image


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Retroracer
post Dec 19 2019, 09:52 PM
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1973 (clocked):
Attached Image Attached Image

- Tony
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Retroracer
post Dec 21 2019, 08:19 PM
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Batch sold!! These three all now have homes - thanks to all who responded.


- Tony
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