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914World.com _ 914World Garage _ GT Tachometer conversion with 10K upm scale, Bosch core
Posted by: Retroracer Oct 26 2019, 11:00 PM
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:
and in the car:
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
Posted by: mb911 Oct 27 2019, 05:48 AM
Sounds very interesting. I know a few people that would be interested
Posted by: rgalla9146 Oct 27 2019, 06:20 AM
I'm in on the 10k tach
Is a GT fuel gauge possible ?
Posted by: roblav1 Oct 27 2019, 06:33 AM
I'm interested too.
Posted by: rothaus Oct 27 2019, 06:46 AM
Could you make it so that the numbers and marking horizontal, like in this picture.
Posted by: Retroracer Oct 27 2019, 08:05 AM
Could you make it so that the numbers and marking horizontal, like in this picture.
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
Posted by: Retroracer Oct 27 2019, 08:08 AM
I'm in on the 10k tach
Is a GT fuel gauge possible ?
This will be just a few 10K tachometers.
- Tony
Posted by: jwinner Oct 27 2019, 07:23 PM
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:
and in the car:
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.
Posted by: gereed75 Oct 27 2019, 07:39 PM
Interested Thanks
Posted by: Retroracer Nov 20 2019, 09:37 PM
Update for those who expressed interest: so the tach fascias from Germany just cleared customs - arrived yesterday. Here's how the "clocked" version looks:
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
Posted by: pete000 Nov 20 2019, 10:04 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.
Posted by: mepstein Nov 20 2019, 10:20 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.
@http://www.914world.com/bbs2/index.php?showuser=12094
http://www.ashlocktech.com/
Attached thumbnail(s)
Posted by: pete000 Nov 26 2019, 08:14 PM
Wow, that's cool. I might just have to build another 10K tach and try this solution. Thanks for sharing
Posted by: targa72e Nov 26 2019, 10:18 PM
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
Posted by: 914dave Nov 27 2019, 05:31 AM
I’m interested
Posted by: rgalla9146 Nov 27 2019, 06:47 AM
I'm interested. 4cyl. tach to 6cyl, 6 pin CD 10k Yes.
Posted by: Retroracer Nov 30 2019, 04:28 PM
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!
- Tony
Posted by: Retroracer Dec 19 2019, 09:50 PM
Now finished:
1969:
1972:
Posted by: Retroracer Dec 19 2019, 09:52 PM
1973 (clocked):
- Tony
Posted by: Retroracer Dec 21 2019, 08:19 PM
Batch sold!! These three all now have homes - thanks to all who responded.
- Tony
Posted by: wurthBob Dec 31 2019, 09:16 PM
If you do anymore 10,000rpm tachs I am interested.
Thank you
Bob
Happy New Year!
Posted by: gereed75 Apr 23 2020, 01:46 PM
Retro, you doing any more of these? Would love to have a “regular” un-clocked one. Thanks.
Posted by: rgalla9146 Apr 23 2020, 03:12 PM
Batch sold!! These three all now have homes - thanks to all who responded.
- Tony
Hi Tony
If you are still willing I'd like to send a tach to have you do it.
I would send a 4cyl. to be converted to 6cyl. (6 pin CD unit) with a
10k standard face.
Please reply
Rory
Posted by: larryM Apr 25 2020, 05:00 PM
some useful info here
http://forums.pelicanparts.com/porsche-911-technical-forum/280714-tachometer-compatibility-chart-2.html
http://forums.pelicanparts.com/porsche-911-technical-forum/965831-tachometer-issue.html
this - validity unverified -
http://www.914world.com/bbs2/index.php?showtopic=298758&st=20&gopid=2423846&#entry2423846
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