10,000 rpm porsche tachometer, can anyone help?

[ryan]

Im not sure, have had some helpfull messages from other members but I want to be sure its real, it came out of a car that was raced through the 80s/90s in Australia by a team that had no budget issues so its just the sort of thing they would have put in the car.

[914-6gt]

If what Armando writes is correct, and I don't doubt it. What you have there is a reproduction.

The date is way too late to be from a R but the real tell is the 24000imp.

http://www.pbase.com/9146gt/10k_rpm_...6gt_original_1

andy

Hi Andy, just a quick note to further clarify my comments regarding the 30000 imp (impulses) stamped in the back of the VDO can and what they mean. The 30000 impulses I was told confirms the fact those VDO instrument were 'originally born as '10K tachometers' and not later converted 10K units. VDO Tachometers that were originally 8K units are stamped 24000 impulses at maximum deflection*. This information comes from a couple of well informed and knowledable sources which I have relied on over the years, Hollywood Speedometer being one of them.

10K VDO Tachometer
30,000 impulses / 60 cyles = 500 impulses
at 50 hertz per thousand (50 x 10 = 500)

8K VDO Tachometer
24000 impulses / 60 cyles = 400 impulses
at 50 hertz per thousand (50 x 8 = 400)

* Maximum deflection relates to the ability of the instrument to accurately read the 'rpm range' it was designed for, the reason why an 8K tachometer could never be an original 10,000 rpm VDO gauge unless it was in fact 'modified' to do so...

Note: If the information I have is not 100% correct, I sure would like to know about it.


In keeping with my goal of only using factory original Porsche race parts in my 914-6 GT project, I sourced and purchased an original 10K VDO tach even with a correct 9.70 date-code and sold the 10K reproductions I had. The reproductions are functionally the same as the originals and there is NOTHING wrong with them.



Torn about how to best restore this gauge. Should I just have it cleaned (lubed, new bezel), but with no new plating?
That would certainly erase the original blue-ink stamp.
Very tempting...

[70SATMan]

I will speculate that the imprinted number equals the maximum pulses seen by the instrument at the max reading (3k impulses per 1k tach reading). So, an 8k tach rightfully maxes out at 24000 impulses and the 10k tach at 30000 pulses.

[914-6gt]

Hello Raj, I'm reading very old notes that may not be quite complete. I will call North Hollywood and check with my source/contact to confirm the details, including the formula/calculation used. All I'm trying to do at this point is get the facts, if nothing else, for my own peace of mind.

Here is a monkey wrench, a gauge with 15000 imp stamped in back...





including a 'red-line' marker

[mike curnow]

I have a 10000 RPM VDO tack with Andial on the front, 05/87 date, and 21000 IMP. Numbers are stamped on the side, don't have a picture.

[ryan]

Hi all, the 4 gauges pictured in my original posting including the 10k tacho have been placed on ebay.com.au (please take note of the au) ending in 10 days time, i tried listing on ebay.com but I had do a million things with paypal and wait three days, pain in the back end! so if anyone is genuinely interested bid away and I will assist fully with getting the gauges posted to you, paypal is available if it suits the purchaser, but bank deposit preffered. i dont believe in wasting peoples time so bid with confidence that the item is in as described condition and will be sent the same day the funds are cleared in my bank account, good luck and thanks to all that assisted, I will list some details of my car and update my profile in the next few days....

[914-6gt]

Then I gave away the two 10K's I had; one was sold for $500 and the other for a bit more at $600, both gauges were converted and restored as new.



A photo of the other...

[914-6gt]

What does converted and restored mean?

Converted from 8K to 10K and restored to look as-new included a new face with the correct 10K Porsche p/n, new bezel, cleaned, lubed, calibrated, etc., etc.

[21window]

Here's mine ?:
<a href="https://picasaweb.google.com/lh/photo/dioqdlreGWtYiuh395Mu7NMTjNZETYmyPJy0liipFm0?feat=e mbedwebsite"><img src="https://lh4.googleusercontent.com/-Wgib0YBM5jg/T4i8MNc7X1I/AAAAAAAALPU/wQJhGLfU9nA/s640/DSCN3314.JPG" height="480" width="640" /></a><p><a href="https://picasaweb.google.com/lh/photo/nM2HKm-cdvt-2KvkGnw1ctMTjNZETYmyPJy0liipFm0?feat=embedwebsite" ><img src="https://lh5.googleusercontent.com/--YeJxF0I8Ns/T4i8Nu9qP7I/AAAAAAAALPQ/220AdzAyiVo/s640/DSCN3315.JPG" height="480" width="640" /></a><p><a href="https://picasaweb.google.com/lh/photo/1eyEaN_tGDi6iSmgWTezRNMTjNZETYmyPJy0liipFm0?feat=e mbedwebsite"><img src="https://lh6.googleusercontent.com/-aBP02xAWjr8/T4i8NskTC3I/AAAAAAAALO8/-V8wVCUZXCE/s640/DSCN3317.JPG" height="480" width="640" /></a><p><a href="https://picasaweb.google.com/lh/photo/mYJW9ufE8vVRYW7l3aLB-NMTjNZETYmyPJy0liipFm0?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-wsssdNWA214/T4i8LSdXitI/AAAAAAAALPY/63YRnnL1wqc/s640/DSCN3312.JPG" height="480" width="640" /></a>

[Bill Simmeth]

IMP on a tach = impulses. The usual metric is impulses per revolution. So I'm guessing Raj had it earlier, the numbers on these are the number of impulses at max reading or, for instance, 3 impulses per revolution on the 30000 imp model.