GT Tachometer conversion with 10K upm scale, Bosch core, small batch being made |
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GT Tachometer conversion with 10K upm scale, Bosch core, small batch being made |
Retroracer |
Oct 26 2019, 11:00 PM
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#1
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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 |
mb911 |
Oct 27 2019, 05:48 AM
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#2
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914 Guru Group: Members Posts: 6,801 Joined: 2-January 09 From: Burlington wi Member No.: 9,892 Region Association: Upper MidWest |
Sounds very interesting. I know a few people that would be interested
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rgalla9146 |
Oct 27 2019, 06:20 AM
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#3
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Advanced Member Group: Members Posts: 4,544 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None |
I'm in on the 10k tach
Is a GT fuel gauge possible ? |
roblav1 |
Oct 27 2019, 06:33 AM
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#4
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Senior Member Group: Members Posts: 528 Joined: 18-September 12 From: KY Member No.: 14,943 Region Association: MidAtlantic Region |
I'm interested too.
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rothaus |
Oct 27 2019, 06:46 AM
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#5
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Member Group: Members Posts: 119 Joined: 20-November 10 From: Virginia Member No.: 12,404 Region Association: None |
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) |
Retroracer |
Oct 27 2019, 08:05 AM
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#6
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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 |
Retroracer |
Oct 27 2019, 08:08 AM
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#7
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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jwinner |
Oct 27 2019, 07:23 PM
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#8
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Newbie Group: Members Posts: 23 Joined: 5-August 14 From: Milwaukee, WI Member No.: 17,736 Region Association: Upper MidWest |
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. |
gereed75 |
Oct 27 2019, 07:39 PM
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#9
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Senior Member Group: Members Posts: 1,239 Joined: 19-March 13 From: Pittsburgh PA Member No.: 15,674 Region Association: North East States |
Interested Thanks
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Retroracer |
Nov 20 2019, 09:37 PM
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#10
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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 |
pete000 |
Nov 20 2019, 10:04 PM
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#11
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Senior Member Group: Members Posts: 1,885 Joined: 23-August 10 From: Bradenton Florida Member No.: 12,094 Region Association: South East States |
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 |
Nov 20 2019, 10:20 PM
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#12
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914-6 GT in waiting Group: Members Posts: 19,222 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
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/ Attached thumbnail(s) |
pete000 |
Nov 26 2019, 08:14 PM
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#13
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Senior Member Group: Members Posts: 1,885 Joined: 23-August 10 From: Bradenton Florida Member No.: 12,094 Region Association: South East States |
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 |
Nov 26 2019, 10:18 PM
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#14
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Member Group: Members Posts: 256 Joined: 11-September 16 From: colorado Member No.: 20,392 Region Association: None |
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 |
914dave |
Nov 27 2019, 05:31 AM
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#15
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914 Addict Group: Members Posts: 700 Joined: 19-October 03 From: Willow Grove Pa. Member No.: 1,262 Region Association: North East States |
I’m interested
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rgalla9146 |
Nov 27 2019, 06:47 AM
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#16
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Advanced Member Group: Members Posts: 4,544 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None |
I'm interested. 4cyl. tach to 6cyl, 6 pin CD 10k Yes.
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Retroracer |
Nov 30 2019, 04:28 PM
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#17
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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 |
Retroracer |
Dec 19 2019, 09:50 PM
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#18
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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Retroracer |
Dec 19 2019, 09:52 PM
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#19
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
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Retroracer |
Dec 21 2019, 08:19 PM
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#20
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Senior Member Group: Members Posts: 608 Joined: 7-July 13 From: Bend OR Member No.: 16,100 Region Association: Pacific Northwest |
Batch sold!! These three all now have homes - thanks to all who responded.
- Tony |
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