Corvette C-1 FI tachometer

[Ray C.]

Over the past few years I have been restoring a 1961 315HP FI Corvette. One item of interest to me was that the tachometer was driven by the distributor, not the generator, and on the back of the 315HP tachometer it was printed, twice the cable speed. Would anyone know when the tack drive distributor and the twice cable speed tachometer was first used on FI cars?

Thanks for any information!
Ray

[Mike M.]

Some 57 FI vets had distributor driven tachs, for example the 43 airbox 57’s. Mike

[Ray C.]

Mike,
any knowledge of when the distributor drive tachometer was used other than the race optioned 1957 air-box car?

as always, thanks for your knowledge!
Ray

[Ray K.]

Ray,

As you are probably aware, all Fuel Injection Corvettes with a mechanical lifter camshaft from 1958 -1961 used the distributor #1110914 which had the rear provision for the tachometer drive. The hydraulic camshaft engines used #1110915 which did not have the tachometer drive and thus were driven by the generator. I have seen the " twice cable speed " notation before but can confirm usage for various applications.

Ray K

[Tom P.]

Over the past few years I have been restoring a 1961 315HP FI Corvette. One item of interest to me was that the tachometer was driven by the distributor, not the generator, and on the back of the 315HP tachometer it was printed, twice the cable speed. Would anyone know when the tack drive distributor and the twice cable speed tachometer was first used on FI cars?

Thanks for any information!
Ray

Beginning in 58, SOLID lifter, FI engines had the 914 distributor. Thus, the tachs on those cars were driven by the dist. therefore, those tachs indicated TWICE cable speed. Also, for 58 only, solid lifter FI tachs were 8000rpm, and NO rev counter.

For 57 ONLY, the 43 Airbox cars had a TOTALLY different tachometer, which mounted to the top of the steering column----NOT in the dash. And those tachs indicated twice cable speed.
Remember, the camshaft and the dist turn 1/2 crankshaft speed (rpm). Therefore, the tach drive cable for for distributor driven tachometers also turned at 1/2 engine rpm. Consequently, the distributor driven tachometers had to indicate twice what the distributor driven cable was turning.

Additionally, GENERATOR driven tachometers had a pulley that was a different diameter from the diameter of the crank pulley----------but not quite half. As a result, generator driven tachs had a different cable/indicting ratio.

[Ray C.]

Beginning in 58, SOLID lifter, FI engines had the 914 distributor. Thus, the tachs on those cars were driven by the dist. therefore, those tachs indicated TWICE cable speed. Also, for 58 only, solid lifter FI tachs were 8000rpm, and NO rev counter.

For 57 ONLY, the 43 Airbox cars had a TOTALLY different tachometer, which mounted to the top of the steering column----NOT in the dash. And those tachs indicated twice cable speed.
Remember, the camshaft and the dist turn 1/2 crankshaft speed (rpm). Therefore, the tach drive cable for for distributor driven tachometers also turned at 1/2 engine rpm. Consequently, the distributor driven tachometers had to indicate twice what the distributor driven cable was turning.

Additionally, GENERATOR driven tachometers had a pulley that was a different diameter from the diameter of the crank pulley----------but not quite half. As a result, generator driven tachs had a different cable/indicting ratio.

Thanks to aLL for the information! I am very interested in C-1 fuel injection cars, but only have basic knowledge about the 1961 model year.

As always, thanks for the education!
Ray