HS2 Carb setting advice for an idiot

[Napoleon Boot]

The idiot in question being me!

For reasons now best forgotten, I decided to fiddle with the jet adjusting screw and as a result, am now struggling to get the engine running.
After checking things like compression, fuel pump, float bowl, spark plugs, cables etc, I decided to tighten the jet adjusting screw up as far as it would go, mark one of the flats, and wind it down two full turns (12 flats) to hopefully get close to a position where the engine would start again.

And it did start - lumpily - until the revs began to die and it stalled. A ha, I thought, getting close! So I gave it one more turn down, and after cleaning the now slightly wet plugs, letting the petrol evaporate from the combustion chambers, turning the key again, no joy (repeat ten times), I got it to run again, slightly less lumpily this time, and without dying.

I hopped out and looked under the bonnet, hoping to fine tune the jet adjustment until the engine sounded normal. But as I reached for the nut, I tapped the bottom of the jet assembly, where the petrol feedpipe comes in from the floatbowl, and the revs immediately dropped and the engine stalled.

Looking more closely, I realised that the whole black and silver assembly moves up and down about one or two mil - I've taken photos of it in both positions. Is this supposed to happen, and is this why I can't seem to get the jet adjusted properly? Perhaps I inadvertently unscrewed the locknut instead of the adjuster?

IMG_7972.jpg (195.81 KiB) Viewed 1045 times

IMG_7973.jpg (210.15 KiB) Viewed 1045 times

Apologies for what's probably a really basic question, but I spent about four hours fiddling this afternoon and I just can't figure it out. Most of the manuals online all start from the position of 'start your engine, now adjust the jet', and it's the first bit I can't get past.

Seb

[pgp001]

Unless the silver ring around the plastic jet body is up against the adjusting nut, turning the nut will make no difference at all.
It looks to me as though the choke cable is partially pulled out and holding the jet in its enriched position.
Around the back of the black plastic body there should be a linkage held on with a small screw, this is connected to the choke mechanism on the side of the carb body.

So you need to make sure the choke is fully in and the cable is not sticking etc, and then the brass part of the jet should go upwards and disappear into the adjusting nut. Only then will your actual adjustments take effect, but at the moment it will be running permanently rich.

Phil

[Napoleon Boot]

Ah, thanks Phil; I must have left the choke partially out that last time and not noticed. I'll try again tomorrow making sure that the choke is in before adjusting the nut.

Seb

[Napoleon Boot]

Back in the car; I pushed the choke back in and the jet assembly responded as it should do. So I tightened the jet adjustment nut again, wound it down 12 flats and tried starting- nothing. Waited, wound it down one more flat to enrichen the mix- nothing. Two flats - nothing.

The plugs can’t be wet as the car has had all night to dry out, though I’ll check them again.

I’m wondering whether my starting technique is to blame, as I’ve only started her in cold weather before, and it’s been hot this weekend. Usually I pull the choke out a little to fast idle, a bit more if the engine won’t fire, then keep it out until the engine warms up. Do I need to do this in hot weather, or am I making it too rich by using the choke?

I’m not touching the accelerator, I only ever use this to get the revs up if the engine fires but sounds like it’s going to stall, then I pull out the choke to compensate.

Apologies if this all seems obvious but I’ve never really had trouble starting before, God I wish I’d left that nut alone...

[pgp001]

Are you saying now that you are trying to start the engine from cold with no choke at all ?

You will find that you need to use the choke any time you start the engine even if it has been running and had time to cool down a bit.
Once the engine has started with full choke, you should be able to push it in to around half way, then when the engine is starting to warm up, you push it all the way in.
Obviously the ambient temperature will have an effect, but you will need the choke for a cold start. I have just got back from a little run out in my Traveller, we went around six miles and the engine was up to temp on the water temp gauge fairly quickly. Having parked up and gone walking for about an hour, I needed to initially pull the choke to about half way out when we started the engine to come home.

The 12 flats setting, is only a recommended starting point for the jet adjustment, you will need to fine tune it from that setting once you start using it, until you get the best mixture by testing the performance and checking the colour of the plugs etc.
https://sucarb.co.uk/technical-hs-type- ... ing-single

Phil

[Napoleon Boot]

Thanks Phil,

No, I usually start the engine the same way as you, I just wondered whether the hot weather made it unnecessary, and that I was making the fuel too rich for the engine to start. Just another possibility to cross off the list.

I’ve taken the dashpot off and checked the jet, needle etc, everything is very clean and no signs of wear. I just double checked the plug leads as well in case I’d replaced them in the wrong order (unlikely as I only take one off at a time). I’ve checked the Earth strap to the car body and it’s fine. Even tried a different set of spark plugs, checked the gaps.

Not sure what else to do really! The frustrating thing is that I’ve got the engine running twice, albeit lumpily, but I can’t get it to happen consistently. Might just have to keep trying, half a flat at a time, hoping that I get it running before I kill the battery

[pgp001]

What you need to do is look at it logically.

Was it starting and running perfectly before you tinkered with the carb settings ?
If it was then there's a good chance you are looking in the right place.

You do need to be certain that the ignition system is working as it should as well, do you have a really good fat blue coloured spark at the plugs when you turn the engine over on the starter with them removed ?

Phil

[Napoleon Boot]

Hi Phil,

Yep, it was running fine before I tinkered with it, so I’m certain it’s to do with the mixture, though I’ve checked everything else I can think of as well. Have just roped someone in to crank the key while I check the spark, will report back.

Ta!

[Napoleon Boot]

No spark!

I checked each plug in turn, holding it close to an unpainted bit of the engine while my mate turned the key, and there was no spark from any of them- it’s very bright out but I tried to do it in the shadows and could still see nothing.

The odd thing was that some smoke did come out of the empty spark plug hole each time, so maybe the other three plugs are sparking a tiny amount?

I rechecked the connections around the coil and dizzy. Obviously it’s never the coil (!) though I do have a spare. I converted to an accuspark a few months ago and it worked a dream, so I don’t think it’s that but could put the old points back in?

Many thanks,
Seb

[Napoleon Boot]

Just for clarity, I did touch the spark plugs against the engine as well, just to be safe.

(Update)

Replaced the coil - it wasn’t the coil.
I remade a wiring connection which I had to make when I fitted the accuspark, as I had my doubts about it, but no dice. Battery seems to be starting to run low so I guess I’ll take it out to charge and try to think of another solution this evening.

[Napoleon Boot]

Success! Of sorts. I suddenly remembered reading a post on here bemoaning the quality of new rotor arms, so I fetched an old one from my spares box, swapped it with the new one that came with the Accuspark kit, and she started first time. Never had any problems up until now so I guess it's just sods law.

I nearly repeated the trick a second time, but pulled the choke out too much and killed the revs, tried a third time but the battery is so flat that it just wouldn't fire up. I measured with a multimeter and it's down to 12.1v, so I've brought it home to charge overnight and will have another go in the morning. Fingers crossed.

[pgp001]

Glad you are making some progress.

Try and get hold of a new rotor arm from the "Distributor Doctor", they are good quality items.
http://www.distributordoctor.com/red-rotor-arms.html

Phil

[Napoleon Boot]

Well, my optimism this morning melted away like an ice cream dropped on the pavement

Armed with a fully charged battery, I tried starting, and nothing.

Roped in my mate to try doing a spark test- nothing from the plugs, and nothing from the king lead.

I tried swapping the coil yesterday and it made no difference, so my suspicions fell on the king lead.

Disconnected it from the dizzy cap (which is pretty tired looking itself), and did a resistance check on the wire, clipping onto the two exposed ends with the multimeter.

The meter stays on 1, which makes me think there’s no continuity, is that correct? When I touch the probes together it drops to zero, which I’d expect if the cable were in one piece. The inside of the cable seems to be made of fine brush like fibers, not braided copper as I’d expected.

The thing that I don’t understand is that when checking the spark plugs, exhaust is coming out of the empty port, so some kind of combustion must be happening, mustn’t it? Or is that just petrol vapor? It is very hot today!

Seb

[Napoleon Boot]

Updating myself which I’m sure is bad form, so apologies!
After stripping away more insulation, I found some strands of what look like metal, so tested there and now I’m getting a reading, there’s resistance, but there is a closed circuit. Crossing my fingers that I might get a spark now- if so, new lead and job done...

Update- that didn’t work either. Flummoxed!

[Napoleon Boot]

Well I think (hope) that I've got to the bottom of it. After checking continuity in the spark plug leads, I found that the lead to plug one had no continuity; after taking the lead out of the distributor cap it was clear why - the first centimeter of wire was charcoal. It looks like the car must have been trying to start on three cylinders, while the connection on the king lead must have been intermittent as well. Hence it would fire up about one time in ten. Strange that it should happen now, she was fine when I last drove her, but I find she sulks if she doesn't get driven regularly and she's been parked up for the last couple of months for obvious reasons!

I've taken the distributor cap home and dismantled it, cut both the king lead and plug one lead back to good wire, and put it all back together. The multimeter now shows a good connection all round so I'll see if I can get it start; the distributor cap does look quite worn though so I'm going to order a new one from the Distributor Doctor.

Seb

[Napoleon Boot]

It sometimes IS the coil!

After replacing the rather tired distributor cap, spark plugs and leads with new ones from Distributor Doctor and Accuspark respectively, I still wasn't getting a spark from the king lead, so I unbolted the old coil and installed the spare.
it was a bit fiddly due to its position and the fact that it wasn't held on with captive nuts, which is why when I tried it before I just rested the coil in place.

This time I bolted it firmly to the chassis, connected all the leads, and the engine fired up on the first turn of the key!

So there we go, fixed at last. I don't begrudge replacing the leads etc as they were all a bit long in the tooth, and the spare coil came with the car, so no huge expense. I now need to have a look at the idle speed as the engine is positively roaring now, but that can wait a little while.

[oliver90owner]

Another time, save yourself - and your mate - some time and effort. Check for spark at the king lead by removing the distributor cap and operating the points with an insulated screwdriver. Doing it that way checks with the condenser in circuit. Battery drain is only about 4A while the points are closed and the ignition is live (a lot more when needlessly operating the starter motor!), no risk of car being in gear when tested, one person job (not two).

[Napoleon Boot]

Another time, save yourself - and your mate - some time and effort. Check for spark at the king lead by removing the distributor cap and operating the points with an insulated screwdriver. Doing it that way checks with the condenser in circuit. Battery drain is only about 4A while the points are closed and the ignition is live (a lot more when needlessly operating the starter motor!), no risk of car being in gear when tested, one person job (not two).

Thanks - I've got electronic ignition though - I'm guessing this only works with points? I did consider putting the old points and condenser back in but didn't want to complicate things any further!

[oliver90owner]

If it is triggered by a Hall Effect device, I would guess it could be triggered by a suitable magnetic field passing by in the right direction?