Burnt tacho cable

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Simon Whittley
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Burnt tacho cable

#1 Post by Simon Whittley » Sun Nov 04, 2018 7:41 pm

Just doing a bit of engine work on my 356 and noticed by tachometer cable plastic sheath is burnt, presumably due to heat from the exhaust.
It still works so I'm looking for suggestions on how to protect it to prevent further damage.
Simon

Peter Poulikakos
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Re: Burnt tacho cable

#2 Post by Peter Poulikakos » Sun Nov 04, 2018 9:22 pm

You could try exhaust wrap.

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Mike Wilson
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Re: Burnt tacho cable

#3 Post by Mike Wilson » Sun Nov 04, 2018 9:47 pm

Mechanical tach? It should be held to the left side engine tray with a P clamp.

Mike
Mike Wilson
Lomita, CA
'63 B coupe

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Juha Vane
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Location: Vantaa, Finland

Re: Burnt tacho cable

#4 Post by Juha Vane » Mon Nov 05, 2018 3:03 am

Perhaps heatshrink tube could be the cure?
The better quality ones shrink quite much and
it’s available with glue and without.
The glue version is a bit stiffer.

If heat shrink tube won’t slip over the cable ends,
you could use self vulcanising tape. When you wrap
it around something the tape bond to itself and make
a perfect seal. Available usually at antenna shops.

I used insulation tube for my full flow oil filter
hoses, it is made in several diameters and
available at speed shops. You should first
verify that cable routing is correct.
And check that the tacho cable is not
a ground cable, that you have a good gound
cable between chassis and engine.
KTF,

Juha Vane
Finland

'59 308
'63 356
'85 911

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PaulAhnell
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Re: Burnt tacho cable

#5 Post by PaulAhnell » Mon Nov 05, 2018 10:09 am

Simon: I had a similar problem and my temporary fix was to wrap the burned portion in fiberglass rafter insulation and then wrap that with thin sticky backed metal tape commonly used to seal joints and cuts in sheet metal heating ducts. See attached. Used a black tie wrap to attach the cable to the valve cover latch up and out of the way of the heat. Ain't pretty but it's functional until I install my new cable.
Attachments
Tach cable 2.JPG
Paul Ahnell
'60 Normal Coupe

Dick Weiss
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Re: Burnt tacho cable

#6 Post by Dick Weiss » Mon Nov 05, 2018 1:02 pm

There's a hole (on the shelf's edge) to mount a clamp to hold the tach cable above the valve cover; Your location isn't correct.

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Mike Wilson
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Re: Burnt tacho cable

#7 Post by Mike Wilson » Mon Nov 05, 2018 1:34 pm

That was my point regarding the clamp. Thanks for the clarification, Dick. Sorry I don't have a picture to post.

Mike
Mike Wilson
Lomita, CA
'63 B coupe

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PaulAhnell
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Re: Burnt tacho cable

#8 Post by PaulAhnell » Mon Nov 05, 2018 2:04 pm

Dick: Thanks for that. I wasn't aware of a clamp, etc. Don't think I have one. I'll take a peek at the parts book to see what's required to correctly mount my new cable.
Paul Ahnell
'60 Normal Coupe

Brad Ripley
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Re: Burnt tacho cable

#9 Post by Brad Ripley » Mon Nov 05, 2018 2:07 pm

From what I'm reading from Simon's post is that he has the earlier version of the tach cable which as has vinyl covering over the entire length. Apparently that vinyl covering is going bad from the heat of the exhaust.

The 356C version, NLA-741-311-01, has steel braided hose over the cable where it goes by the exhaust tube under the valve cover. This is the version currently manufactured and in the photo below. The hose piece is supposed to protect the cable from the heat.

And, as Dick points out, you will need the proper clamp.
Attachments
Tach cable detail .jpg
Tach cable detail .jpg (22.52 KiB) Viewed 292 times
Tach cable clamp 511 036.jpg
Tach cable clamp 511 036.jpg (3.86 KiB) Viewed 292 times

Tim Berardelli
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Re: Burnt tacho cable

#10 Post by Tim Berardelli » Tue Nov 06, 2018 7:50 pm

Aeroquip has a product called "fire sleeve" no need to reinvent the wheel.

Hugo Karasawa
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Re: Burnt tacho cable

#11 Post by Hugo Karasawa » Wed Nov 07, 2018 2:11 pm


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