Float level ? S1 4.2 does not start

[Durango2k]

All,

I tried to start my S1, because it‘s about to go to the painter.

It only starts on starter spray, runs a few seconds, then dies. I am relatively certain its the float level, because it runs smooth and nicely - but on spray only.

So, I set the fuel level to 11mm- which is nearly 7/16“- but I think that is too low. My current plan is to simply try a 10mm level, and hope that will help. No chance at 11mm

Am I right that the jets are set to be flush with the bridge, then turned 2.5 rotations down at the screw in the lower left corner ? Where would my fuel level be visible in the jet, then ? Is the jet then to be „flat covered with fuel“ ?

I cannot see fuel in the bowl- when I push down the float it comes up.

Is it correct that moving the choke lever upwards pulls down the jets by another few mm ?

It would help me a lot if I could get it running, because my Imp just killed its gearbox... I have to get the E away from blocking the lift + to get the nose painted.

Carsten

[politeperson]

The XK engine can be difficult to bring to life at all from cold unless you have full choke.

I would check the jets are dropping all the way on the cable.

[mgcjag]

Hi Carsten....yes set the jet level with the bridge......then turn down 2.5 turns......ideal if you use a digital caliper and set each jet down 2mm as a start point.........fuel should be seen down in the jet...not level with it.....when you operate the choke it should pull each jet down. .........ensure that the needles are set correctly in the piston...7/16 is the correct setting for the floats.......also ensure that you have the correct serated washer fitted on the top of the float chamber as a breather..........Steve

[Durango2k]

Regarding the choke: It does do a first click without any movement, then every click moves the jet down. How far (in mm) should the choke bring the jets down ? Guess 2-3mm from bridge level ?

Then another 2.5 turns takes them down another 2mm ?

I have the serrated washer, I have fuel pressure.

I really don‘t understand why it does not get fuel .... all I can think off is fuel level...

Carsten

[mgcjag]

Hi Carsten.....have you checked the needles.....UM are standard....just check this is stamped on the needles....yes initial setting is jet down from bridge 2mm.....not sure how far the choke pulls down the jets.....check with a depth guage...should all be similar.......re check float setting to 7/16....check that fuel pump is working.....and fuel filter Steve

[Durango2k]

Needles are new. They were a bit greenish after the winter, but cleaned up easily. I centred them.

My main problem is language. I try to follow Mr. Heynes, but he simply uses terms like „then adjust the mixture control rod“ giving zero indication which item that may be.

I also cannot find any video online, isn‘t that amazing, that shows a basic setup from scratch on an E- Type. You find several videos on youtube for Austin Healeys, but their carbs are a bit different. Or rebuild videos, or polishing videos, but nothing about how to get the darn thing to do actual work :-)

So - my only conclusion at the moment is go to the shed, at plus 3 degrees, and start documenting what I have, what I tried, and what my understanding of the parts and screws is. I will take photos and videos.

„Something must be wrong with my little machine - mecanic said your car’s allright Lightnin‘, you‘ve just been burning bad gazoline“- said Lightning Hopkins in „my starter won‘t start this morning“....

[mgcjag]

Hi Carsten...this should help...this info is in the Jag service manual and we have them in the knowledge base section...re the needles...check whats actually stamped on them....incorrect needles have been supplied in the past

[Durango2k]

Ok, I‘ll re- read them... have them somewhere here as well.

Carsten

[paulsco]

Hi Carsten,

You say it starts on spray but then stops.

Could it be bad fuel or perhaps an ignition problem?

Paul

[Durango2k]

It never really ran after full rebuild. It runs on spray - my son said it my also be timing far off, because spray is more flameable / more tolerant.

But where do you start.. iirc I set it it to -10 (per book), then turned the dissi until spark 6 (frontmost) just fired and thats it. That should do it ? At least near ? I can of course re- check and document that.

We‘ll be out for a walk this afternoon, but I‘ll start photos and doc tonight.

Carsten

[Durango2k]

.... does anyone have the spring parameters for the large damper spring in the dome ? I remember last time I noticed that the centre piston did move up and down a bit, some mm, when it ran on spray for 5 seconds, but the outer two did not.

Maybe a good idea to compress them to a certain hight and measuring the force they give on a 1/100 gr scale (which I happen to have in the kitchen, an old lab scale, 6100 gramms by 1/100).

But I need to know how far to compress and which force then to observe...

Carsten

[christopher storey]

It will not be the springs . The only function of the springs is to prevent the piston reaching full lift too early , and they have no function in determining mixture strength itself .The XK is always hard to start after a layoff because of the length and volume of the inlet tract . Try 10 second bursts on the starter - on full choke always - with 15 seconds rest in between. You may easily need up to 10 such bursts before you get a kick - often just as you release the button because of coil robbing . Once you get a kick you know you have ignition, and the answer is then to keep going until you can catch such a kick with the throttle. You may well find it dies after a few seconds, but just keep repeating the process - you will achieve a start in the end

[Durango2k]

Given the size of the compartment, is a uranium batterie needed, then ?

The one I have cannot do that. Buy a Red Top 4.2 first ?

Maybe I put my Diesel E (class) next to it and use my 25 mm solid wires ?

Carsten

[paulsco]

I have had some success in the past on initial start up by un-screwing the damper pistons completely and just leaving them in the pistons and then trying a start.

My understanding of this is that it allows the pistons to rise easily, thus allowing a richer fuel mixture into the engine.

I could be wrong of course, but it has helped me on several occasions.

Paul

[christopher storey]

I'm not saying it wouldn't help, Paul, but in fact allowing the piston to rise more easily weakens the mixture in a constant depression carburetter, rather than richening it. This is because as the piston rises it increases the cross-sectional area of the carburetter bore and thus reduces the depression over the jet . This is why using too thick an oil in the damper richens the mixture on acceleration

[paulsco]

Good point Christopher, but in my case it has worked.
Perhaps letting the air in more easily is what helps

Paul

[christopher storey]

Paul : yes, it's interesting isn't it? If I don't get a start or at any rate a cough after perhaps 5 or 6 sessions on the starter, I sometimes knock the choke off and give it full throttle for a couple of sessions to see if it clears any flooding, and that sometimes works too. I feel sure that it is the length and volume of the inlet tract which is the problem, because if you start them every few days, there is (usually) absolutely no trouble, with an instant start

[Durango2k]

I have now been there, and found a few things.

- one of the float levels was way out- I set them all to 11 mm, and I now have fuel on all thre around 2 mm below the bridge level.
- I found one thick idle screw was out by 3 turns not 2
- the needles are stamped U1, not UM. They are all new, iirc from Joe Curto. Is U1 a known variant ? I set them all using a .40 mm feeler gauge, this felt nice in the needle slot, so I could set the gauge in the slot, push needle up, tighten screw, job done. All 3 set this way.

—wait I just found that U1 is the needle for the twin carb HD8 Rover 2000 from 1967/68. In this car it serves 1 litre per carb, in the E-type its 1.4 ltrs / carb so theoretically they might be quite „off the scale“ from what I need ? Why have I been sold these... ? Will check the old ones that came with the car and trial fit them.


- I measured voltage at coil, it is 8.8-9.1 when cranking, but I get a spark at plug 3.
- checked compression with thumb: its a lot. Cranking pushes my thumb out instantly, so „enough“.
- measured the plastic landing inserts in the carb pistons. They are only 0.25 mm high, so this is the height of the slot the air must get through. I could not yet find a value for the slot, but iirc it was 0.25-0.35“ - which is a lot more then .25mm. Maybe the inserts are too flat ? Can they be renewed ? Why did they not use a worm screw....hm, maybe thats a repair method which would give an adjusteable piston landing.
- I now understood the screws on the left rear of the carb. They open the throttle discs when the choke lever is moved upwards by 1-3 clicks. The discs only just move, but no gap is to be seen there. But they move. I set these screws to just touch the lever when the choke is fully „off“. Maybe this needs a bit more like 1 or 2 rotations ? In normal mode, choke off, the discs close the inlet. I adjusted the linkage accordingly, which was a bit tricky, because some joints are worn.
- I took the springs back home, will measure tomorrow. No colour codes on them anymore. Maybe the paint was the same as on my east german gazoline camping stove, it was not fuel resistant, so it instantly started to rust.

[mgcjag]

Hi Carsten...ok so you have the wrong needles but it your photo above the needle is not positioned correctly. ....see the instructions i posted above showing the needle position in the piston.....Steve

[christopher storey]

UI are slightly richer than UM but not as rich as UE or UO which are commonly used richer needles ( although i advise against them unless your engine is radically modified ) . They certainly should not prevent you getting a cold start. However, it seems from what Stuart has said ( I really cannot see myself on your photo what has happened) that you have not positioned them correctly - I always set mine with the shoulder flush with the base of the piston - and if you have put them significantly lower than this then you will have very weak mixture, which could well explain your non-start

PS I am not really sure what your reference to plastic inserts is about. Where and what are these ?