Starting from cold with Dellortos

[jimj]

"Your concern strikes me as being born of too many years driving modern fuel injected cars that don't do that. Your expectations are skewed. No Weber or Dellorto will start like fuel injection."
Tim, err, no, as I said I was comparing it with the S3 on Webers which fires up immediately with 2 prods of the accelerator even after a few days, that`s the whole puzzle.
I certainly don`t want to fit an electric pump, inertia switch, filter, pressure regulator, extra wiring etc. especially as I`ve experienced many others on events having problems with their`s. I don`t recall it being a problem 40 years ago but maybe I just don`t recall.
Jim

[jimj]

So, today, 24 hours since it last ran and starting at a similar temperature, it took loads, dozens, of turns of the engine before it fired up on Dellortos. On the S3 with Webers, which has stood for 6 days, the engine turned once then fired up with just 2 prods of the accelerator. I struggle to believe that Dellortos were always like that, why is the fuel disappearing from the carbs. and fuel lines overnight in one car and not the other?
I`d try introducing fuel straight into the fuel line but there doesn`t seem an easy way.
See pic.
Jim

[terryp]

Jim
Have you checked what pump jets you have?
I have some horizontal 50's if you are interested

Terry

[jimj]

Terry, carburettor internals are a mystery to me and the dog. Neither of us know which pump jets we have nor where to find them, though Fido thinks they may be under the bonnet.
Jim
P.S. Fido isn`t his real name

[terryp]

Jim
I'm sure that someone will have better graphics but undo the big slot headed screw No 50 on the diagram. Remove the jet and have a look. Horizontal ones are as the picture. Vertical ones have the hole in the end!

Dellorto diagram

Pump jet

image.jpg (8.63 KiB) Viewed 1592 times

Bon courage as we say here!

Terry

[alexblack13]

Hi Guys...

Using the rubber primer bulb sorted my issues completely. I then fitted an electric pump and regulator set to about 1.5 psi . A few pumps when cold and it starts instantly.

I have the primer bulb available if you want it. Works a treat!

I need the address of anyone who wants it... FOC ....

Al' ....

[lotusfan]

Jim

I think we need a bit of history to give us a chance of finding the solution to your problem. How long have you had the car? Has it always been difficult to start from cold? Have you done any work on it recently?

I too have a Sprint with Dellortos and since I first got the engine going, about 2 years ago, after a restoration it was always a pig to start. It had all the right bits including a bulb priming pump, new leads, a red rotor arm and sideways facing jets but you could never guarantee it would start. I formed the distinct impression that it would only start when the ignition key was released and wondered if the coil voltage was too low when the starter was operating but never got round to investigating that until very recently.

Having connected a voltmeter between earth and the coil I operated the starter and the voltage disappeared!!! To prove the point I connected a temporary lead to the coil from the starter solenoid and it started as it should have done. Investigation showed that I had connected the ignition switch incorrectly not helped by the replacement switch having different ident numbers from the wiring diagram.

My current starting technique is 2 or 3 dabs of throttle then turn the key and catch it on the throttle until it warms up a bit.

So, might you have an ignition switch wiring error?

[jimj]

As I said at the beginning: " I followed Mark`s advice replacing the whole, everything, ignition system, fitting 123 electronic ignition. I had the carbs. set up by a specialist with a rolling road yet still it`s the same." You`ll see on following posts that the car starts fine the same day, once it`s been started, even hours later, it`s just the first time each day. Incidentally, the ignition was also set up on the rolling road.
Is the garage haunted but only at night? Why would it start 8 hours later in the day but not 10 hours later overnight? It`s just altogether strange.
Jim

[types26/36]

Just a suggestion here, I think Deltortos have a habit of "syphoning" the fuel from the float chambers into the manifold when stood for awhile ...........overnight? ......maybe due to the temperature drop?
Anyway it effectively "floods" the engine so have you tried just pushing the accelerator SLOWLY to the floor, holding it down then trying to start the car?
No choke and no pumping of the acc pedal, if it does fire then you may have to catch it using the acc pedal.

[Plus 2]

Jim,

Just to offer a slightly alternative route may be worthwhile to check out, many many years ago I had a similar issue of continual cranking with one of my Elans always thinking it was fuel starvation. However I can't remember if it was Dellorto or Weber as I have had both types at times having had 17 Elans. However I can say I never was aware of any performance differences with either carbs in general use.

At first when I got the car everything was fine, yet poor cold starting and I mean even on a hot day the car just seemed difficult on initial starting but fired up easily thereafter.

Having done all the usual tuning and replacement parts, leads plugs, coil (I even wired in a ballast circuit with resistor and ballast coil and tried fitting electronic ignition) etc to still see no improvement. Then I noticed one day when washing the car the headlamp pods were not staying up as long when lifted up to clean.(all my cars have been non failsafe spec)

This lead me to investigate the quality of the vacuum system, both lights and servo and the discovery of a small split in the T piece on the front chassis take off. It would appear this could seal itself off at high suction/vacuum engine running but not on cranking.

After this was replaced I then noticed the car was back to normal for starting quality and no continual cranking required.

As a matter of course on all my cars I now renew and check all vac line systems.

Depending on standard or failsafe see how long your system holds the vacuum if the engine is just switched off as it is a good sign, or just try starting the car with the vac line take off points at the manifold clamped off.

All the best

Steve

[jimj]

Steve, PLU5 2, genius, clairvoyant, exorcist, or...................? Clamped the vacuum line and brrrm. Sure enough, close examination of the T piece revealed a tiny split so I`ll order a new one on Monday and email you a pint.
Thanks a pint.
Jim

[Elanconvert]

glad you got that sorted, jim.... PO of my car had similar experience!

on a more general note, my s4 on dellortoes starts immediately from cold with a couple of pumps...
HOWEVER, I deliberately turn the engine over for 10 secs or so BEFORE pumping the accellerator, to ensure that there is OIL everywhere before firing...... habit I got from when I turbo'ed an imp engine, to make sure there was oil at the turbo.....

fred

[alexblack13]

glad you got that sorted, jim.... PO of my car had similar experience!

on a more general note, my s4 on dellortoes starts immediately from cold with a couple of pumps...
HOWEVER, I deliberately turn the engine over for 10 secs or so BEFORE pumping the accellerator, to ensure that there is OIL everywhere before firing...... habit I got from when I turbo'ed an imp engine, to make sure there was oil at the turbo.....

fred

Nought wrong with that idea. Oil is good!

[jimj]

Well, it wasn`t sorted after all. I`ve found I could use almost a whole battery full of churning just to start the car but thereafter it was fine. Air, spark, petrol, that`s all you need and I knew the air and spark were ok so, today, I put a fuel bulb in the line from the tank. I squeezed until it was firm and the car fired at the first churn, hoorah and I went for the first Elan drive of 2015. Clearly, the mechanical fuel pump provides enough pressure, even on full throttle, when the car is running but not enough at starter cranking speed. Why?
The, hardly convenient, fuel bulb fix is just temporary. I want to keep the car exactly to factory spec.
Jim

[UAB807F]

Well, that sounds a reasonable theory, and one that you'll certainly be able to resolve because we all know that once upon a time the mechanical pump was up to the job. It might just be that the valves aren't operating properly at low speed but you've proved that there's enough pump action for it to work once the engine is running.

You can (or at least could) buy overhaul kits for the Ford pump which replaced all the rubber bits inside, and it was relatively simple to overhaul your old glass bowl pump. I think I've even seen them on Ebay so it sound like it's worth a shot ?

Brian