Sun Tachometer Retrospective

[markeb01]

If you have an interest in vintage gauges or if you’re tachometer compulsive like me, the following narration may be of interest. What follows is a history of the original Sun tachs and some observations about the new retro model. The historical perspective is accurate based on my own experiences, so there may be some technical inaccuracies in chronology. Please share any corrections, if someone knows more than I do. This stuff matters to me since I see so many people build “vintage” cars with parts that are really from decades before or after what would be correct for the period. That, and my wife reminds me I’m nuts and have way too much time on my hands!

Here’s an ad for Sun tachs from 1966:



The RC model Sun tachometers were the pioneers in performance tachs, and were a must have accessory. They were exceedingly popular in the 50’s and real race cars frequently had one, along with all the cool cars in hot rod magazines and at the local drive in. Popularity increased again when Chevy stuck them in their 409 cars, with the knee knocker mounting. This design enjoyed a very limited lifespan from roughly the late 50’s to the early/mid 60’s. By the end of the 60’s the RC/FZ style was dead, having been superseded both in production and popularity by the full sweep Sun Super Tach. Being around for such a short but memorable period, evolutionary changes occurred rapidly.

Dixco jumped on the band wagon making a more affordable replica which ended up in a lot of high school cars, but it was kind of like having Portawalls on your tires. They looked great in pictures but everyone knew they weren’t the genuine article.

Along with an assortment of rpm ranges and face designs, there were 3 basic variations of the early Sun half sweep tachometer head, along with 3 different cups. They could also be panel or dash mounted, but my focus is on the cup mounting. The early RC models were sold as 2 pieces, the tach head and the transmitter box. The head indicated the rpm range, and needed a compatible transmitter depending on the number of cylinders, voltage, and ground. The transmitter ran a unique battery with an odd voltage, and once out of production the tachs mostly ended up in the garage until electronic conversions became available.

1. The original head/face design shared similar styling with the new retro FZ88R production, having a chrome face with a smooth indentation below the window.



Many of the earliest gauge faces had a large red oval near the bottom of the window. This face design is now referred to as the “football” tach. (A lot of magazine writers lacking familiarity with old Sun tachs often incorrectly refer to any half sweep tach as a football tach). The gauge faces for GM factory installations had a yellow and “red line” imprinted on the face. There were also other designs with various color sweeps under the rpm numbers, but the chrome metal portion of the head remained unchanged.

The earliest cup available was what is now referred to as the “pinch cup”. It had a split in the bottom of the cup along with a pair of small angle brackets spot welded to the cup to clamp the tach head in place. The tach wires exited one of two holes near the bottom of the cup, and the mounting bracket (one for dash mounting, one for column mount) had a ¼” hole for the mounting bolt to attach the bracket to the cup, using a dished threaded washer inside. This style cup is now being reproduced by Show Cars Automotive:

http://www.show-cars.com/cgi-bin/com...ction&key=3597

2. For lack of an official description, the next generation of cup had a pair of “dents” or cavities in the lower rear corners, for chrome acorn retaining nuts. The split in the cup, the spot welded brackets, and the wiring holes in the cup were eliminated. The head was now retained in the cup by the mounting studs on the back of the gauge, and wiring left the cup via a hollow bolt holding the bracket and cup together. The front to back length was similar to the pinch cup, perhaps a tad longer. This was a much smoother design and was also easier to clean and wax. Sunpro has recently released a virtual duplicate of this design identified as the NC-5 cup, which includes both mounting brackets.

http://www.sunpro.com/product_detail.php?pid=16514

About this time or a bit later, the tach head gained a “black dot” at the bottom center in the recessed area of the face. This was actually a stylized Bakelite screw head allowing external adjustment to zero the pointer, and remained until the end of production.

3. Somewhere in the early/mid 60’s a transistorized version was released and no longer needed the separate transmitter. Sharing the same tach head style as the RC models, this was identified as the FZ model. The FZ88N was an 8 grand tach, and there was a 10k version with a different part number. The electronics previously held in the transmitter box, were now contained in a separate can attached to the back of the tach head. This necessitated a longer cup to house the new length of the head assembly. I believe (but cannot confirm) the part number for the “long cup” is NC-1. The FZ88 was the model I fell in love with – long cup, black adjusting screw, RC style face. It lived a very short life, since the Sun Super Tach was released soon after and immediately dominated in popularity.

For me, the original half sweep Sun tach was one of the 60’s icons I longed for in the years before I had a license, along with a Hurst shifter, American Mags, Moon pedal, Covico wheel, Corvette valve covers, and Cal Custom dash knobs. Until now only the tach has eluded me. I’ve been looking for a new old stock or mint condition original for almost 10 years, but could never afford anything I wanted. In the interim I did find an NOS mint condition NC-1 long cup, and tried to make myself happy installing a Moon/Autometer tach head. Although it functioned correctly, I thought it looked stupid and was always disappointed with the arrangement. A few days ago I discovered the recently released Sunpro FZ88R, and last Friday took the plunge and bought one, hoping it would look decent enough to work. To my amazement it was shipped Saturday and arrived yesterday, traveling 2,000 miles over the weekend!

Since the new model comes in the shorter NC-5 cup, a bit of work was required on the internal hardware to get it to fit properly in my NC-1 long cup. Fortunately I have a junk original FZ88N for parts, so I robbed the pieces I needed including the Bakelite pointer adjusting screw.

It’s now mounted up and in my opinion makes a pretty decent substitute for an original.




Pros – It looks pretty cool. Unlike other air core tachometers, the needle rests at zero against a peg when turned off. It always bugged me the Moon tach (and other air core tachs) leave the needle anywhere in the range when switched off. It works perfectly with HEI ignition. It appears very accurate and responsive. Cosmetically it’s a close simulation to the casual observer. It has green LED lighting, which should last indefinitely, and illuminates the gauge face nicely at night. It is correct in size, and fits perfectly in the NC-5 cup it comes in.

Cons – the new window opening overall is smaller than the original and doesn’t look quite right. (Why can’t anybody just make a reproduction that looks exactly like the original)? This makes the gauge face appear to be mounted abnormally low in the window. On original tachs, alignment of the gauge face to the window is infallible due to the mechanical design of the parts. On my retro tach, the face has a tiny tilt to the left in the window. In the internet circulated promotional photo I notice a slight tilt to the right.



This is not user correctable. The chrome on the face is mediocre production plating, not bad, but no where near the quality of an original RC/FZ tach. The chrome on the cup is much better than the face (nearly as good as NOS originals) but close inspection reveals minor linear scratching under the plating. There is definitely no copper under any of the new chrome, it’s just nickel over bare steel. I have an NOS original NC-5 cup and it appears to almost be show chrome, but compared to the cost of restoring an original the new reproduction would be a great addition to any original vintage tach for anything less than a six figure show car.

Note – the new FZ88R will also work with coil on plug ignition equipped engines, and diesel engines with electronic injection – but – you will also need the CP7560 Tach Signal adapter, and I don’t think this is mentioned anywhere but in the instructions - after you have purchased the tach and opened the packaging.

Note – the new retro Sun Super Tach does not appear to have a zero peg/rest for the pointer. In internet photos the needle drops almost straight down when off, which instantly identifies the new version as not being an original.



Overall – I’m very pleased with the results and will close the chapter on looking further. To the casual observer it looks just like an original, and works well. Cost has always been a prime consideration for me. I paid less than $130 delivered while the cost of an NOS original Sun tach can run $200-$500, and if it’s the earlier RC type, requires another $175 (or more) to convert it to modern functionality.