More running issues

[George]

Hey everyone,

I had my 32' Sports gearbox overhauled and a few other jobs done by John Parker at the end of October. It has been running lovely since and have taken it out on a few nice journeys. However, this afternoon I pushed it out the unit just so I could run it up to temperature and shunt it up and down the drive a few times to keep the brakes free but it wasn't behaving very well.

I left it ticking over for a good 30 minutes, giving it some revs every now and then to warm it up. When I wasn't giving it any gas though it was idling too low, not stalling, but always seemed on the verge. Then when attempting to put it into gear to move away the revs dipped so low that I had to keep a steady pressure on the throttle to stop it stalling. I thought pulling away would be fine as it just seemed the idle was too low but sure enough each time I put it into gear and moved off it went a few feet before conking out.

Now I don’t want to go undoing all of John's hard work tuning the carbs so before going and increasing the idle speed I thought I'd get some advice first. Could it be as simple as the idle speed causing this? And even if that's not the solution its definitely idling much lower than last week so is that normal that they should require fettling so often?

My initial plan was to up the idle speed a bit and see if that does the trick. Otherwise strip the carbs and give them a clean as the inline filter has a small amount of rust (And give that a clean too) which might have made its way intothe carbs. But any advice from people who know what they are doing would be great!

One other small thing, my fuel gauge always reads full despite having a new tank sender unit. I want to get this sorted it drives me insane! Should I try buying another gauge and see if that sorts it? Or should I buy a complete gauge, wiring and sender assembly to guarantee they will all work together? Out of curiosity what would the original gauge manufacturer be? Currently it is an AC unit same as this:

https://www.ebay.co.uk/itm/AC-PETROL-GA ... 635-2958-0

But the speedo is Jaeger and the oil pressure/coolant temperature is Smith's. If I get a full new assembly would be good to get the original manufacturer.

Thanks all!
George

[mikeC]

A couple of thoughts for you: you don't mention using the choke. The last few days have been dramatically colder than back in October which means the air is going to be denser and effectively will give you a weaker mixture. It is not unreasonable in cold weather to need the choke pulled out a short distance even when the engine has apparently warmed up sufficiently - the first part of the choke operation should just give a faster idle, further use will start to enrich the mixture. I am presently running a Vintage Austin Seven which has separate controls for idle-speed and choke, and in the present weather I need to keep a faster idle for at least ten miles of use before the engine will idle comfortably on a closed throttle.

Another problem due to the colder weather could be icing-up - probably not appropriate with the Singer carbs being above the exhaust manifold, but it's worth checking.

And finally, how old is the fuel? Modern fuel seems to go stale very quickly and your symptoms are remarkably similar to those I suffered with my Lancia, which was eventually resolved by fitting new spark plugs!

Oh, and increasing the idle speed on the carburettor linkage won't affect the set-up of the carbs, and can easily be returned to the previous setting if that doesn't improve things.

[George]

Hi Mike,

Thanks for all the useful advice! Regarding the choke, I have only been using this for starting the car and keeping it out for a short while afterwards before fully pushing it back in. I didn't give any consideration to this as I thought the choke was just used for initial starting and maybe kept out a few minutes thereafter. I will definitely try running it with the choke to get some kind of balance and see if this helps.

Regarding the other 2 points, I don't think ice could have been the issue. Like you say with the carbs directly above the manifold they don't stay cool for long, and yesterday when I ran it we were around 5 or 6 degrees with it out in the sun so it shouldn't be the issue. And there may be some older fuel in the tank (No more than a month) but I added 10 litres of fresh fuel to it last weekend (The premium stuff, obviously) so I guess that's not old enough to cause issues? It's always kept topped up with fresh as the darn gauge always reads full so to be on the safe side it's always got plenty in there.

Cheers,
George

[Peter McKercher]

You might want to check the choke linkage to make sure it actually is fully pushed in, not just at the knob.

[jeans_old_man]

I wouldn't fiddle with John's settings but have a close look at the choke and throttle linkages and make sure everything is working as it should. It is always worth removing the main jets and giving them a blow through. This lets any debris trapped in the float chambers to run out. Modern fuel absorbs water so flushing out the carbs will eliminate that too. It is also very sooty, so swapping out the plugs is worth while. It is amazing how black they get.

If the car was running fine when you put it away it is unlikely to be anything serious and it probably needs a bit of a run to clean the plugs and points and bed-in the valve seats etc.

As for the fuel gauge, a permanent full reading suggest that the tank unit is not earthed. If you short the sender wire to chassis the gauge should read emplty. If you have a multimeter you can measure the resistance of the sender. It should read zero ohms when empty and 30 ohms full. The original gauge had a Singer logo on it and was probably made by AC. I don't think the nines had a temperature gauge fitted originally but usually had an aftermarket one - Motometer?