Mk1 choke cable

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
Post Reply
Message
Author
Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Mk1 choke cable

#1 Post by Clifford Pope » Sat Nov 17, 2018 11:08 pm

I've just read widget's request for a source of a new cable, and I am puzzled by the reference to the two sections with the rubber joiner.
I've sometimes wondered about this. Mine has the short link of rubber, a sort of washer/clamp at each end, and a springy metal link wire holding the two bits together.
Apparently it is meant to be some kind of electrical switch?

I've had two Mk1s, 1964 and now 1966, and neither has had any trace of any electrical connections or wiring.
But there is nonethe less a switch somewhere else controlling the choke light. When I turn the ignition on and start the engine, there is no light. But after a very short time - about the time when you would want to push the choke in, the light comes on, but goes out when the knob is pushed in. There clearly must be a thermostatic switch somewhere, as well as an over-ride switch to turn the light out. (It works in exactly the same way as the one on my LandRover, except that that has a special thermostat in the front of the engine block by the outlet hose.)

The book only shows a simple on/off switch, no thermostat. Where is the thermostat, where is the switch, and what is the choke cable link for?

johnnydog
Senior Member
Senior Member
Posts: 820
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: Mk1 choke cable

#2 Post by johnnydog » Sun Nov 18, 2018 12:48 am

The original Mk 1 choke cable as you say was in two sections joined with the rubber jointing piece, with a 'star' type washer at each end ; however the two sections had a habit of separating when the choke was pushed in, which caused the inner cable not to return properly. This was primarily due to the profile of the fast idle choke cam on the carb linkage being the wrong profile. It was too severe so that a little movement of the choke resulted in too high engine revs but insufficient choke enrichment. The cam was often reprofiled by tuners to give a more gradual choke / engine speed increase, which also helped the choke cable to return smoothly.
The piece of wire you refer to was often added to try to keep the two sections of the outer cable together. It wasn't fitted when new.
As for the choke warning light switch - it was a bakerlite connector block secured to the solid outer part of the choke cable immediately behind the facia. It was held by two grub screws; the indents for the grub screws can be seen on the solid piece of the outer body of the cable. The wiring should be there for the two terminals that come off this connector. Its the same connector incidentally as on the Mk2 choke cable.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Re: Mk1 choke cable

#3 Post by Clifford Pope » Sun Nov 18, 2018 9:12 am

It's hard to see, but I presume mine must have the bakelite connector switch otherwise the light wouldn't be working.
But where is the thermostat? There must be one because the light doesn't come on immediately, only after a few minutes of running. It's a clever reminder to put the choke in.

johnnydog
Senior Member
Senior Member
Posts: 820
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: Mk1 choke cable

#4 Post by johnnydog » Sun Nov 18, 2018 5:09 pm

Thermostat? There's no thermostat on it. When the choke knob is pulled out the warning light comes on irrrspective of engine temperature, and only goes off when the choke cable is pushed back in. The light is controlled purely by contacts in the switch on the solid section of outer cable that operate when the choke cable is pulled.
I think you will find that it is purely poor contacts in the switch - sometimes when the choke light doesnt come on, and you twist the choke knob whilst its pulled out, you will find the light may flicker or come on momentarily. It isn't an ingenious work of science by Triumph that causes your choke light to come on and off - you just have a dodgy choke warning light switch!!!
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Re: Mk1 choke cable

#5 Post by Clifford Pope » Sun Nov 18, 2018 7:52 pm

It's a very reliable dodgy switch then! I used the car this afternoon and it worked in the usual way. No light when I started up, but after a few minutes the light came on. It's quite easy to forget the choke - it's on a spring so won't stay out more than about 1/4", but it's easy to forget that.
I'm pretty sure my previous 2000 did the same. I assumed it worked in the same way as the LandRover, which I've been familiar with for years, as does indeed have a thermostat.

How very odd - perhaps there's a heat-activated timer in the switch - it makes contact after a set time?
Once the engine's hot pulling the choke doesn't turn the light on - which would fit with the heating element theory.

Well well - a gremlin. :)

johnnydog
Senior Member
Senior Member
Posts: 820
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: Mk1 choke cable

#6 Post by johnnydog » Sun Nov 18, 2018 8:03 pm

If it's on a 'spring' and won't stay out more than 1/4", and with the other 'gremlins' you describe, it sounds very much like its not the standard set up, or the adjustment or set up of the solid inner cable isn't right or it possibly just requires lubricating. I've had several Mk1's over the years, and currently have two - both of which are standard (the Royal Blue Mk1 has a re-profiled fast idle cam) but none have had the issues you describe.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Re: Mk1 choke cable

#7 Post by Clifford Pope » Mon Nov 19, 2018 8:30 am

Thanks for the information.
It's not actually an issue,more a useful feature I thought they all had. :)

Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Re: Mk1 choke cable

#8 Post by Clifford Pope » Fri Nov 30, 2018 9:41 am

I've solved the mystery - it was the light bulb.
I took it out and tested it. When first connected it appears dead, but after about half a minute it comes on. A bit like a joke birthday cake candle but in reverse.

I've put a new bulb in, so of course it works properly now, but isn't so useful.
I'm now thinking of putting in a proper "otter switch", so it does work as a warning light.

johnnydog
Senior Member
Senior Member
Posts: 820
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: Mk1 choke cable

#9 Post by johnnydog » Fri Nov 30, 2018 3:34 pm

At least the issue is now sorted - I didn't think Triumph engineers/ designers were that advanced in their day!!!!
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

Clifford Pope
Senior Member
Senior Member
Posts: 779
Joined: Fri Mar 19, 2004 3:50 pm
Location: United Kingdom

Re: Mk1 choke cable

#10 Post by Clifford Pope » Fri Nov 30, 2018 3:47 pm

johnnydog wrote:
Fri Nov 30, 2018 3:34 pm
I didn't think Triumph engineers/ designers were that advanced in their day!!!!
Unlike Rover, who fitted a thermostatic otter switch even in the primitive Series I Land Rover. :)

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests