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 Post subject: Burnt tacho cable
PostPosted: Sun Nov 04, 2018 7:41 pm 
356 Fan
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Joined: Wed Jun 27, 2012 4:54 pm
Posts: 28
Location: Edinburgh, UK
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.

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Simon


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 Post subject: Re: Burnt tacho cable
PostPosted: Sun Nov 04, 2018 9:22 pm 
356 Fan

Joined: Tue Apr 15, 2008 1:09 am
Posts: 113
Location: Sydney Australia
You could try exhaust wrap.


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 Post subject: Re: Burnt tacho cable
PostPosted: Sun Nov 04, 2018 9:47 pm 
356 Fan
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Joined: Tue Apr 15, 2008 4:37 pm
Posts: 3846
Location: SW Los Angeles
Mechanical tach? It should be held to the left side engine tray with a P clamp.

Mike

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Mike Wilson
Lomita, CA
'63 B coupe


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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 3:03 am 
356 Fan
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Joined: Tue Jul 01, 2008 3:06 pm
Posts: 87
Location: Vantaa, Finland
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.

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KTF,

Juha Vane
Finland

'59 308
'63 356
'85 911


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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 10:09 am 
356 Fan
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Joined: Mon Jul 08, 2013 3:18 pm
Posts: 344
Location: Lyme, CT
Tag: What?
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
Tach cable 2.JPG [ 1.35 MiB | Viewed 179 times ]

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Paul Ahnell
'60 Normal Coupe
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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 1:02 pm 
356 Fan

Joined: Sun Apr 20, 2008 12:54 am
Posts: 2892
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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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 1:34 pm 
356 Fan
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Joined: Tue Apr 15, 2008 4:37 pm
Posts: 3846
Location: SW Los Angeles
That was my point regarding the clamp. Thanks for the clarification, Dick. Sorry I don't have a picture to post.

Mike

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Mike Wilson
Lomita, CA
'63 B coupe


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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 2:04 pm 
356 Fan
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Joined: Mon Jul 08, 2013 3:18 pm
Posts: 344
Location: Lyme, CT
Tag: What?
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.

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Paul Ahnell
'60 Normal Coupe


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 Post subject: Re: Burnt tacho cable
PostPosted: Mon Nov 05, 2018 2:07 pm 
356 Fan

Joined: Tue Mar 25, 2008 9:28 pm
Posts: 3303
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 137 times ]
Tach cable clamp 511 036.jpg
Tach cable clamp 511 036.jpg [ 3.86 KiB | Viewed 137 times ]

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 Post subject: Re: Burnt tacho cable
PostPosted: Tue Nov 06, 2018 7:50 pm 
356 Fan

Joined: Wed Apr 30, 2008 7:02 am
Posts: 281
Location: Washington DC Area
Aeroquip has a product called "fire sleeve" no need to reinvent the wheel.

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 Post subject: Re: Burnt tacho cable
PostPosted: Wed Nov 07, 2018 2:11 pm 
356 Fan

Joined: Fri Sep 09, 2016 10:40 pm
Posts: 170
Something similar that this
https://www.demon-tweeks.com/uk/design- ... ng-242405/


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