(07-03-2024, 11:36 PM)David Cochrane Wrote: Interesting comments, but many of them irrelevant, as Peter has a 26VA side-draught carb.
Oooops
Didn’t read the op properly. However most of the comments are still pertinent.
If the carb is a 26VA on a 1930 car it is most probably fitted to the later manifold but coupled to a D shape fuel tank. Generally there is sufficient head to feed the carb unless the tank is low on fuel and the car parked on a slope. However sometimes I’ve found a little ‘sticktion’ even on the updraft carb needing the float needle to be pulled up to get fuel moving.
On a different point the Austin handbooks suggest that the ignition should be advanced even when hand cranking. Isn’t this a recipe for a broken wrist?
The 26VA should not need "flooding", but if you haven't used the car for a few days the float bowl may empty a bit through evaporation. This can be overcome by using the priming lever on the fuel pump to manually pump fuel until the needle valve cuts off with the bowl full. If you don't do this, you have to wait until the engine turning over on the starter has done the same job. An alternative is to turn the engine over on the handle half a dozen times (ignition off), which saves having to open the bonnet and delve in.
The 26VA choke is an air strangler. By restricting the air supply, a lowering of air pressure occurs downstream of the strangler flap, which "sucks" fuel out of the jets. Because the air flow at cranking speeds is so low, the strangler must cover the passage almost completely (it has just a small hole in its centre) so it's worth checking that the cable and cam mechanism are doing their job properly.
If for some reason the fuel level in the float bowl is too low when the needle valve cuts off, this won't help matters.
Once fired up, erratic idling speed can be a sign that there is an air leak somewhere in the carb or inlet manifold. When idling, manifold vacuum is high, so even a tiny leak will result in extra air being pulled in and weakening the mixture. Check the manifold gasket for leaks, the carb to manifold flange and the throttle spindle for wear. Once underway, small air leaks like this have much less effect on running.
I don't know whether it's modern petrol or what, but I find that both of my Austins (1934 Ruby and 1955 Cambridge) both need a bit of extra petrol to help them start unless they were running yesterday.
I have a small squirty bottle with petrol in, a squirt into the air intake, full choke, and they start almost instantly.
To save opening the bonnet, I now do this with the seven...
Ignition off, full choke, spin it on the handle as fast as I can for as long as I can. Ignition on, then it starts immediately.
This is exactly what I had some years ago.
Do check that part 22 above is the right way around. If the groove is away from the body then the strangler can't completely close. That was my problem. 5 years of poor starting fixed in about 30 seconds.
Again hanks for all the advice. I’ll check the choke actuation to make sure it fully effective. No fuel pump so can’t prime other than by cranking. Float sitting too low is worth a check, and I’ll certainly give the manifold heating a try. Would a sloppy strangler spindle add to air leaks.
And I'll vouch for that one too. Mine had the wrong bowl/top combination. Much smoother running once I got that right too.
Now, I am being told that the raised veggie bed needs finishing off ready for the potatoes, so no more forum for the moment...lots of stone to move.
Andy
Just a comment on whether to set advance or retard when cold starting.
I take the point of a risk of handle kickback with the advance setting.
For anyone new to hand starting use the rule of thumb
Looking at the Ruby handbook there is no mention of ignition setting because this auto advance
Which would suggest a retarded setting is best
After rereading this I am not sure it makes a lot of sense
However is getting late so I bid you all good night
