S1 4.2 hard to start

[Durango2k]

I'm still having trouble to start my engine.

Currently, I can start it using a rattle can (Startpilot), which sprays an ether into the trumpets.
Leave foot of gas pedal, set choke to max, spray into three trumpets, push button, and she's instantly alive.

Pistons in carbs elevate to about 1\2 inches from the bridge, I can see the fuel being ripped inside (you really see spraying fuel there, and the inlet vacuum is monstrous compared to what I am used to from my Maserati engine. It then does about 2500 rpm.

I sprayed the manifold with the ether to check for vac leaks. None found. Spray ether into running engine - and revs go up, pistons rise, it all looks fine.

But why won't it start without the rattle can drug ?

The choke lever pulls the jets down, and I believe it mooves the throttle discs a bit (will verify).

What more can I try ?

Exhaust ist sooty (new but some carbon deposits.

Carsten

P.S.- freakin' moment tonight. Was working at night, dark behind the car. Started, I looked back and saw a huge orange flash and lots of smoke. Thought it's fire from the exhaust. It was the RHD indicator and exhaust fumes. Pheew. Extinguishing this kind of garage fire was easy.....switch of on stalk.

[JagWaugh]

I'm still having trouble to start my engine.
...
Currently, I can start it using a rattle can (Startpilot), which sprays an ether into the trumpets.
Leave foot of gas pedal, set choke to max, spray into three trumpets, push button, and she's instantly alive.

Pistons in carbs elevate to about 1\2 inches from the bridge, I can see the fuel being ripped inside (you really see spraying fuel there, and the inlet vacuum is monstrous compared to what I am used to from my Maserati engine. It then does about 2500 rpm.
...
But why won't it start without the rattle can drug ?

The choke lever pulls the jets down, and I believe it mooves the throttle discs a bit (will verify).
...

Carsten:

Do you mean:

1) The car won't start without Ether, but once it starts it will run fine?
or
2) The car won't fire without Ether, but with ether it will fire and run briefly at about 2500 rpm?

If I remember correctly the choke control slide on the dash should only open the butterfly for about the first half of the travel, then any further travel lowers the jet. With the choke control slide OFF the fast idle screws should be about 0.5mm off the lever they act on.

You've got the filters off if you're able to spray Ether into the throats. If the car will run once started, then go through the shop manual procedure for checking that the butterflys are synched, the bypass (volume) screws full in, then back out by 2 turns, adjust the mixture screws until the jet is even with the bridge, then 2-1/2 turns in. Now start the car with Ether (or gasoline from a spray bottle) and get it up to normal running temperature. Balance the three carbs using a Unisyn and adjusting the bypass screws, then check mixture with the lift pins and adjust. Then adjust the idle down to 500 without choke, then adjust the chokes.

Because the choke is a two stage action, cold start problems due to choke adjustment can be either extreme:

1) The butterfly is opening, but the jet isn't lowering, so you're allowing lots of air, but no corresponding increase in fuel (i.e. your choke is just pressing the gas pedal - if the engine would start cold by just pressing the pedal then SU wouldn't have messed about with producing the 4 differing choke systems they did).

2) The jet is being pulled down but the butterfly isn't opening enough. This one is easy to spot as the choke "works" when you hold the gas pedal down a bit.

2500 is a bit high for idle even with the air filter off. Are you absolutely certain that your butterflies are all closed at rest, and that you've no false air getting in? The o-rings and springs on the bypass screws sometimes make it hard to be sure that you're starting the adjustment procedure from the "full in then 2 out" datum, but if you can get the engine to run at something near 1500 rpm you can balance the carbs with a Unisyn.

I personally think the hose on the ear method is a myth - the only thing I've ever achieved with that is to tell if the carb is indeed pulling air - this is useful to figure out if someone left a ball of cloth in the intake manifold when they were refitting the carbs, but for adjustment you can't beat the Unisyn.

[Durango2k]

Hi Andrew,

It is option 1- once started it stays aluve at 2500.

I am now somewhat confident that I can "drive" it, get it back into the garage which has a small entry step again under XK power, so I'll get some more air into the tyres (5 different ones in 3 sizes all from about 1970), bleed the clutch using Felix' (14 yrs old), and the do what you wrote outside the garage. Otherwise, no more posts, because if I try it inside, I'll be dead in 2 minutes no joke.

I did do all the adjustments you wrote several times, which is what stumbles me so much. Why does it not even nearly coughs, then, with all settings as per Haynes etc. ? It makes no sense.

But give it "the can", it fires in a millisecond and swings up to 2500 stable idle.

Carsten

[Durango2k]

I think it may be a good idea to take a few videos for youtube and put the links up here today ? I'll be having the time so I'll do that.

Carsten

[Durango2k]

Oh and I do have a colortune and a unisyn, btw., so that's there.

Carsten

[cactusman]

I would agree with Jagwaugh. Sounds like the choke mechanism is simply not set up correctly. The first click or two up should open the butterfly valves in each carb a bit....bit like gently pressing the accelerator...then more clicks should lower the jets so buckets of fuel are pulled in when you crank the engine.
Firstly work through jagwaughs list then see if things improve. Once running you should not need the choke for more than a minute or two unless it is bitter cold. The engine should settle and idle around 700 rpm or so.

It can be tricky to set all three carbs To synchronize correctly but patience and a carb balance device help enormously

[Mikael B]

Hi Carsten!
Your problem is as you say "Pistons in carbs elevate to about 1\2 inches from the bridge".

Pistons should rest on the bridge and you need to adjust the jets to have the piston free falling to the bridge.

This is not easy with carbs in situ but I think it can be done. See instructions in the manual.

Regards

[Durango2k]

Hi Mikael,

No, normally they fall down as per manual.

I wanted to say that they elevate once the engine runs, and they the do lift and fall, according to the rpm the engine runs at.

I gave it a very short try an hour ago- it did start on full choke (hurray, but surely there was enough remaining fuel from yesterday in the manifold), and it did settle a lot nicer on the lowest choke click setting.

Carsten

[Mikael B]

Sounds like you are on the right way and final adjustments are needed from now.

I my case I'm have never finished this.

[mgcjag]

Hi Carsten.......also when you try starting dont press the accelerator pedal ......great to hear you have it running....looking forward to hear your driving... Steve

[PeterCrespin]

It is option 1- once started it stays aluve at 2500...

...give it "the can", it fires in a millisecond and swings up to 2500 stable idle.

2500 is not engine idle. 2500 is an engine almost racing under no load. To breathe enough air to race at 2500 rpm, there is too much air (too lean a mixture) to start the car as normal - in my opinion.

[myharris]

Regarding starting, don't underestimate how much a good battery ground affects starting.Clean/wire brush the grounding point.

[Hugo]

Sounds like you simply have the fast idle screws way too far open. In fact I wouldn't mind betting that the linkage is resting on these screws instead of the correct idling screws. Push the choke in & the fast idle cams should be well clear of the adjustment screws. Once you've done that, you have a better chance of getting her to start. Or just back them off a couple of turns & see what happens. At the very least you should have a more sensible idle speed. At present, the throttle is being held too far open for it to suck enough fuel in, which is why you have to help it along with ether. That is also why the engine is racing on tickover.

[chrisfell]

Hugo has a point. One of the features of the E-Type throttle control mechanism is the huge number of parts involved that are capable of fouling things up.

I recall an E-Type guru giving a quick lesson is how to set up SUs. After adjusting the individual carbs ( floats heights, jet heights, pilot air screws etc) to the manual, he then went along the throttle mechanism from the pedal box to the carbs slackening everything off, including the choke adjusters. Then starting back at the pedal box everything was re-set.

The setting process involved lots of touching and feeling for movement, which is almost impossible to describe, it has to be seen and experienced.

[Hugo]

Yes, lots of little ball joints & bushes that can add up to quite a lot of play. And yes, the best way is to put your fingers on the joints & feel for play rather than looking for it. Those ball joints are not particularly good - they generally wear out of round, so if you adjust the play out, you get tight spots and a sticking throttle. I have a Mangoletsi cable set=up sitting on the shelf waiting to go on mine. But the carbs themselves are delightfully simple, and also very tolerant. SU's can be a mile out & still run reasonably well.