Mechanical tachometers, what years?

[jerryg]

I have a 1967 911S which I am restoring. I am going to use a 1969 911S engine which has been converted to carbs. Will the 1969 engine have a pick up for the 1967 mechanical tach? In other words, I do not know when Porsche changed from a mechanical to an electrical tach.

Thanks for the reply, in advance.
Jerry G

[edmayo]

All production Porsche's used electric tachs. Only the race cars used mechanical tachs.

[Harvey Weidman]

As Ed said, Porsche changed when they went from the 4 cyl 356 to the 6 cyl in the 911.
The race tach drive is off of the cam as I recall.... I can't imagine the grief or the benefit of a mechanical tach in a 911.
They were/are a pain in the 356 IMHO.
H

[jerryg]

I got wrapped around my own axle when reading an article about tachs. A mechanical tach discussion was regarding racing tachs. Thanks for the clarrification regarding the rest of the story. And yes, I do have an electrical tach.

[Jim Breazeale]

Porsche ended mechanical tachs in street cars In 1964. 1965 YM 356s were fitted with electric tachs.
Just for grins, my 1957 Studebaker Golden Hawk had an electric tach!

[Harvey Weidman]

Looks like my efforts to erase all 356 knowledge from my memory is starting to work....
Thanks Jim for the correction. I succumb to the master of all things 356 related....forgot about the last gasp 65 C tach....(It was my unnecessarily feeble attempt to clarify Ed's response)
H

[jerryg]

Here is what got me on this link. When redoing the '67 911S I am working on the tunnel. I removed what I believe to be a damaged mechanical tach cable running from the instrument area to the engine bay. Since the instruments (and the rest of the car) is stripped, and my memory fading from a year of other auto work, I was not certain just what it was connected (if ever) to. Because most of my work in the past has been on 356s, I began to research the use of mechanical tachs and found that they were on racing cars. Because of the input in this thread I dug up the tach that came with the car, and it is, indeed, electrical. But that begs my really stupid question, "Just what is the cable that I thought was for a mechanical tach?" Were they put in some, but not all, 911S, for racing? Or is it not a tach cable? I now feel like a real rube.

[Jim Breazeale]

Here is what got me on this link. When redoing the '67 911S I am working on the tunnel. I removed what I believe to be a damaged mechanical tach cable running from the instrument area to the engine bay. Since the instruments (and the rest of the car) is stripped, and my memory fading from a year of other auto work, I was not certain just what it was connected (if ever) to. Because most of my work in the past has been on 356s, I began to research the use of mechanical tachs and found that they were on racing cars. Because of the input in this thread I dug up the tach that came with the car, and it is, indeed, electrical. But that begs my really stupid question, "Just what is the cable that I thought was for a mechanical tach?" Were they put in some, but not all, 911S, for racing? Or is it not a tach cable? I now feel like a real rube.

It is the spedometer cable. 911s drive the spedometer cable from the transmission while 356s drive the spedo from the LF wheel hub.

Regards

Jim

[jerryg]

Thanks, Jim. Now I feel a little less "rube-less." Note my saying after my name. I hate to ask these "obvious" questions, since I've been a 356/912 Porsche-file for so long. No wonder I could not find the speedo sender attachment on the front wheel! But I learn something every day, thanks to these sites. Once again, it was a pleasure talking to you at the Lit Meet. Thanks for your great work with EASY. FYI, the replacement cable is being built at North Hollywood, my go-to instrument guys.

[ejboyd5]

since I've been a 356/912 Porsche-file for so long.

porsche-phile - small point, but very important.