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For those that have a black widow tribute, these were fitted with a tachometer.
They were cable driven off the generator, and fitted around the steering column in front of the cluster.
Some Questions I have is if you have the power steering pump off the generator what else can drive it., or were they not fitted to power steering driven cars.
What brand manufacture were they, also are there vintage electric tachometers available that look like the originals?
 

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ALLLLLLLLLLLLLLLLLLLLLLLLLLL 57-74 Corvettes had a distributor with a tach drive. The 58-61 Corvettes with ONLY solid lifter, fuel injection engines (all others were generator driven) had the tach drive distributors. In 57, ONLY the Airbox Corvettes had a tach drive distributor..
Beginning in 62, NO EXCEPTIONS, ALL Corvettes up through 74 had a tach drive distributor------------regardless of base engine, hi-perf engine or fuel injection. Any and all Corvette distributors SB and BB, will be a pure, 100% fit in ANY SB or BB engine.
Tach drive distributors for LATE 60s up through 74 BASE ENGINES will be fairly easy to find and will be the cheapest to buy.
Thus, if a car has a generator driven pwr str pump, then a tach drive distributor would be an excellent way to go.
Furthermore, generator driven tachs have more of a tendency to have some needle wobble because of the generator belt flopping around it higher rpm's. But a distributor driven tach remains very steady.
Last, for a street driver car, one of the distributors with a vacuum advance would be a much more compatible tach for a driver. The advance curve, weights, springs, are all interchangeable, so the dist can easily be set up to suit a particular engine and drive train.

This is a fuel injected engine with the tach drive dist on a customer's 62 Corvette. The tach drive uses the exact same style cable connection as a speedometer cable.
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This is the style vac adv tach drive distributor that was used on carbureted 62-74 Corvettes. They are not extremely common, but there are plenty of them out there for sale.
BEFORE BUYING ONE, UNSCREW THE FITTING FOR THE CABLE AND CHECK THE CONDITION OF THE DRIVE AND DRIVEN GEARS!!!!!!!!!!!!!! The driven gears are readily available, but if the gear teeth on the shaft are excessively worn or chipped, there is NO fix. The shaft must be replaced and they are available from the aftermarket Corvette vendors-------------------for a price!!!
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The circa 1957 Black Widow tach's were AC 8000 RPM mechanical units. With fuel injection they are distributor driven. If there was an electrical variant of it, I have not seen one. Could it have been driven by the back of the generator? With the correct hardware probably yes. Here is how the distributor driven mechanical one looks... Al
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That AC 8000 tachometer was part of the 1957 Corvette RPO579D option (aka, Airbox cars).. But,. the tach and bracket continued to be listed in the Chev parts books for 2-3 years for folks that wanted to add a mechanical tach (at that time, all that was available were the Sun elec tach). At one time, Stewart Warner offered a mechanical tach, but I don't think it was available back in 1957. Back in the late 70s I was trying to find one of the AC 8000 tachs with no luck.The S-W 8000 tach had also been discontinued. But as luck would have it, just for the heck of it, I called the S-W headquarters, talked to some guy who said they were no longer available, BUUUUUUUUUUUUT, he thought there may be one or two back in the warehouse. He went and looked and found 3 still in the boxes. I said I'd take them!!! I ran the S-W tach on the 56 Vette for a few years until I finally came across an AC 8000 tach and I made my own bracked from heavy gauge stainless sheet metal.
I have never been able to determine for sure how the tachs from the parts dept were calibrated, for a generator or a dist. The ones which came on the 57 Vettes were only calibrated for a distributor (indicated 2 times cable speed). Also, from 58-74, ALL Corvette dist driven tachs were 2 times cable speed, and gen driven tachs were different (I don't know the exact ratio).

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Discussion Starter #9
Great info, I gather then on a Chevrolet the tachometer mounting position was on the heater delete position, were they ever mounted around the steering column like the corvettes.
 

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Great info, I gather then on a Chevrolet the tachometer mounting position was on the heater delete position, were they ever mounted around the steering column like the corvettes.
If they were, I have never seen one, nor heard of one being mounted on the column. Back in those days, those kinds of things were done however they worked.
 

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I can not imagine that power steering would have been on a real black widow
That is correct.
But if someone wants to build a tribute car, it could certainly be added. PLUS, if it was added using all period Chevy factory type parts in the way that it would have been done by the factory, it would certainly have an authentic appearance.
 
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