1937 Ruby spark plug colour ?

[David Stepney]

Joe. Exactly the problem I had! I managed to blagg a spare carb from a friend, but I am sure that someone will have a float chamber or even a spare carb you could purchase. They turn up on ebay occasionally.

[Joe eck]

David
Hopefully one will turn up soon.

I will try ringing round the various A7 parts suppliers and see what they have.

It's quite amazing how I have spent many many hours under the bonnet and never noticed the mis match. Mind you, I have also spent hours looking for stuff in my garage only to find it right in front of me at a later date !!

Thanks
Joe.

[David Stepney]

Joe. Don't be too hard on yourself. The carb mismatch is by no means obvious. Ruairidh had to point it out to me.

[Parazine]

On the original subject...….

This is the colour I have on the Chummy, running a 1" SU. It's also the only Austin Seven I have had in over forty years that will do a genuine 40+ MPG!


   


I think the outside of the plug runs cooler than the electrodes, hence the black. However, the tan is pleasing to see.

[Joe eck]

My plugs are a shade or two lighter so I think I will have to richen it up a little once I have the correct float chamber for my carb.
In anticipation of this replacement , does anybody know an initial idle mixture screw setting for a 26va ?
Thanks
Joe.

[David Stepney]

I suspect they all vary. I screw the mixture screw right in and then out one complete turn as a starting position.

[Joe eck]

Thanks David that's very helpful.

[David Stepney]

I also give the throttle stop about 2 to 3 turns up to give a good sharp tickover. Get the engine warm and then play with the mixture screw to get the engine running at its fastest. Take the tickover down  to a more sensible level and play very gently with the mixture screw again to get the engine running at its most even.
Snap the throttle open and release. If the engine 'dips' and then return to a tickover, screw the mixture in a tiny amount until it no longer does this.
If the tickover gradually gets lumpier and slower, then the mixture is too rich. Again screw the mixture screw out a tiny bit until the tickover is consistent and even.
Once you have got the mixture right, set the tickover to a sensible speed and check the mixture again. I usually set my tickover to a speed when the ignition light just comes on on the  'Summer' charge setting but that may be a bit slow for some people - its all a question of taste really. The tickover speed can vary quite considerably with engine temperature.

I know it sounds a bit of a fiddle, but it is worth taking the time to get is as right as you can. It makes for easy starting hot or cold.

Hope this helps!

[Joe eck]

Thank You David for the comprehensive explanation, much appreciated.
It's always nice to have a bit of guidance on these matters.
Regards
Joe.

[Ian McGowan]

This might be useful for you Joe.



  Zenith 26VA Carb data sheet.pdf (Size: 277.98 KB / Downloads: 49)