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Esprit Turbo project car - part3 - the further continuation


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  • 1 month later...
On 24/04/2020 at 09:41, Lotusfab said:

Grub screw removed from camshaft for internal cleaning. I' m using a rifel barrel cleaning method. Little cloth and a plunger!IMG_1413.thumb.JPG.f07e306b021db6e0834cdaa8840785fa.JPG

Hi, do you have any tips for removal of the grub screw. Mine seems very deep and it feels like either the allen key will break or the screw will fail. It doesn't want to budge. Thankyou

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Mmm, I have taken out quite a few. Make sure the allen head is very clean so the allen key can get all the way in. I would soak it in wd40 overnight and try the next day. Heat might help. Good luck, they do come out if you persist and they are tight. Try clamping the camshaft on a bench and a long arm allen key.

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1 hour ago, Lotusfab said:

Mmm, I have taken out quite a few. Make sure the allen head is very clean so the allen key can get all the way in. I would soak it in wd40 overnight and try the next day. Heat might help. Good luck, they do come out if you persist and they are tight. Try clamping the camshaft on a bench and a long arm allen key.

Thankyou for your response.  I soaked it in wd 40 with the camshaft in the vertical position last night and thankfully with a huge sigh of relief they both cam out this afternoon.  I soaked the cams in petrol and cleaned them with a long brass bottle brush. There was some debris inside so a job worth doing. Thanks once again. I must admit last night I had visions of a damaged hex with all that that entails.  Oh the Joy's of Lotus!

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11 hours ago, PrecisionMike said:

Thankyou for your response.  I soaked it in wd 40 with the camshaft in the vertical position last night and thankfully with a huge sigh of relief they both cam out this afternoon.  I soaked the cams in petrol and cleaned them with a long brass bottle brush. There was some debris inside so a job worth doing. Thanks once again. I must admit last night I had visions of a damaged hex with all that that entails.  Oh the Joy's of Lotus!

Well done. Blow them through with compressed air and wrap them in something until you get to putting them back on.A Lot of bits on the car do take persuading to get off, but they all come apart eventually. Tracking down tools that work is half the battle. Getting the bits out of the camshafts is an essential bit of the build. Good luck with the rest.

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  • 2 weeks later...

Car just had its final MOT the tester was impressed with the emissions, I was worried as always…Looks like the tune at Northampton Motor sport was worth it, although they did say it wasn’t really necessary to adjust anything. We went up one jet size although they said it could be left. It took me ages to solve the stumble problem, but have to say its now as good as it can be. The solution was not the jets, but to reduce the choke size. Remember I installed forged HC pistons. Over 1000 miles now done and it drives really well. Such a difference to when I first drove it! Anyone who has tried tuning these cars will understand why the numbers below are impressive. 29846809-1BB1-4CC5-9A7C-674A71DC4ED2.thumb.png.4e34a7f75d9559c6c227bb24fcf0e978.png

 

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28 minutes ago, Lotusfab said:

Anyone who has tried tuning these cars will understand why the numbers below are impressive.

Awesome numbers indeed - I got the HC ppm on mine to 1090ppm which is just below the threshold of 1200ppm (after 2 days of playing with the carbs) !!!! Will need more work for next year's MoT.

 

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I've been doing some reading, and am thinking of going up one size in main jets to cure a mild stumble at ~3000 rpm. Have  now just borrowed a colortune; already have manometer, so weather permitting, will try and fine tune. Just need to borrow/blag gas tester 😉 

6 minutes ago, Lotusfab said:

a very simple but unexpected solution

Which was ? 🤔

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9 minutes ago, thebartman said:

I've been doing some reading, and am thinking of going up one size in main jets to cure a mild stumble at ~3000 rpm. Have  now just borrowed a colortune; already have manometer, so weather permitting, will try and fine tune. Just need to borrow/blag gas tester 😉 

Which was ? 🤔

I am running HC pistons, but LC carbs so my set up is different.

C7546B07-D763-410B-86CA-CFC2660D0C17.thumb.png.b67049b7656c0c3f63abd79c9c2a9050.pngI tried all of the jetting for the 45M carb using my 40H carb. I found the mixture was far too rich, the progression holes in the carb body are different. In the end I left the smaller 35 mm choke in with the standard 40H jetting, but a few sizes up on the idle jet. Now perfect. I stumbled across the solution by rejetting and testing. It takes a lot of time and effort.

If you have a standard engine and everything is good ie no air leaks, carbs good condition and floats correct height.  I think the stumble is probably caused by weakness in the mixture. Its not at main jet at the rpms your talking about so the solution is confined to the idle jet. So if your pump jets are clear and adjusted correctly two things you can try. Increase the idle jet size by 2 and see how you go or try a richer idle jet holder. There is a table for them with the numbers that tell you weather its leaner or richer. You could try the smaller choke, it makes the engine more stable at lower rpms, but can degrade it at its maximum performance. My car made 180 BHP on the rolling road at about 75 per cent throttle.

Alternatively, spend £300 with Northampton Motor Sport who can switch out the jets on the road under load. They will get to the solution much quicker if your fed up messing around.

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On 18/10/2021 at 10:41, Lotusfab said:

I am running HC pistons, but LC carbs so my set up is different.

C7546B07-D763-410B-86CA-CFC2660D0C17.thumb.png.b67049b7656c0c3f63abd79c9c2a9050.pngI tried all of the jetting for the 45M carb using my 40H carb. I found the mixture was far too rich, the progression holes in the carb body are different. In the end I left the smaller 35 mm choke in with the standard 40H jetting, but a few sizes up on the idle jet. Now perfect. I stumbled across the solution by rejetting and testing. It takes a lot of time and effort.

If you have a standard engine and everything is good ie no air leaks, carbs good condition and floats correct height.  I think the stumble is probably caused by weakness in the mixture. Its not at main jet at the rpms your talking about so the solution is confined to the idle jet. So if your pump jets are clear and adjusted correctly two things you can try. Increase the idle jet size by 2 and see how you go or try a richer idle jet holder. There is a table for them with the numbers that tell you weather its leaner or richer. You could try the smaller choke, it makes the engine more stable at lower rpms, but can degrade it at its maximum performance. My car made 180 BHP on the rolling road at about 75 per cent throttle.

Alternatively, spend £300 with Northampton Motor Sport who can switch out the jets on the road under load. They will get to the solution much quicker if your fed up messing around.

Sorry misread your rpm 3000 is main jet. Go up two sizes and see.

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  • 3 weeks later...
  • 1 month later...

Some time ago I changed the starting technique. I started to do five presses of the accelerator and then start the car. Before this I just used the choke. I started using  this technique on my S1. In recent months I have found both cars getting difficult to start and then my Turbo would not start.  I have upgraded both to High torque starter motors, but did not reinstate the extra voltage across the coil for start. Both cars have never needed it. 
I extensively examined the Turbo. The reason it would not start was carbon fouling! Pressing the pedal five times makes it very rich for start. I then did very short trips never heating the engine to operating temperature. The plugs never heated up to burn off the excess carbon. I took the plugs out cleaned them and it started first time and runs perfectly.

The lesson here is if you are using this technique you must run the engine to operating temperature. I am now going back to the use of choke. When  I used the choke before I never experienced any start issues on either car!

I did check the fuel pressure on the Turbo when I was fault finding. I found it was too high. I was able to adjust it to 4.5, but the screw is further out than it should be. Everything on my car in the fuel system is new except the regulator. The diaphragm is deformed but intact. Whilst seeking a replacement  I discovered the operating pressure of all new regulators is 5 psi! This is too high for the Turbo. I have ordered one to test. If 5 psi is the minimum achievable it means there are no original fuel pressure regulators available for the Esprit. The model is Malpessi FPR010. I have written to Malpessi, but doubt if they will reply. This is like the Thermostat problem. It took nonths to source the correct one whilst all the ones available for sale were unsuitable. There must be a lot of Esprits out there that are not running correctly as these parts will have reached end of life by now. The results will be erratic cooling temperatures and poorly running engines or maybe even carb flooding. I will report back when I have tested the new regulator.

Just a word more about the spark plugs. If they get black with carbon the ceramic insulator gets coated in it. The spark then arcs across the ceramic to the screw body and not across the spark plug gap. Thus the fuel will not ignite. By coincidence my neighbour has a 1935 Riley. He could not start it. I checked and he had fuel. I asked him to take the plugs out. As soon as I saw them I realised they were carbon fouled. We cleaned them up. It started first time and run perfectly. Like me he had been doing short trips and starting it without getting it hot. The plugs are self cleaning at operating temperature.

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Five presses seems excessive anyway: I have always been a three-press advocate (30+ years across various 900-series engines) but recently have reduced it to two. Although sometimes I do give the choke an exercise for a change. 

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I find it can’t self sustain with no choke unless you used four or five presses. I was advised to use this start technique, but will be going back to just using the choke. The reason I was given was to avoid the choke sticking open and driving without realising. 

Lucky I have only been doing this technique in the last year.

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I use the choke PLUS the presses - but only when cold - and have done so since 1987. I always run up to temperature, unless moving out of the garage for a wash - but then I normally go for a drive afterwards.

I never drive with the choke on, always wait for the oil to get up to pressure, closing the choke as the pressure rises. The revs drop at the same time, so I know that the choke hasn't been left on. This is done before the car moves out of the garage.

Hot starting is a different matter, easy on my Excel, more of a churn on the Esprit, and a hope plus crossed finger - always starts in the end though.

I use the choke for cold starting on the Excel as well.

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All very interesting ..

My own 85TE has a choke, and when starting from cold ( I always) have the choke on. In the winter (like yesterday at +3 deg C) I add ONE accelerator pump just to ensure some fuel is in carbs.

If in summer, its just choke for a lesser time.

The car has a hi-torque starter.

As soon as engine starts to warm, I reduce choke until self-idling - usually about 3-6 mins.

Also, as soon as practical (self-idling=OK), I disengage the choke.

I then start the drive carefully to get everyting else up to normal temps/pressures etc.

Hot starting - is a nightmare. When I can get it re-started, I have to leave running for ages until cold fuel in in the carbs, otherwise I can stall the engine with just a slight touch on the throttle !! - Makes for very interesting shopping car-park exits :blush:

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 . . . . and give it some Wellie once things are up to temperature. There is no comparing in-cylinder conditions between light cruise and full throttle. As to starting technique pumping the pedal is certainly a crude method, yielding inlet tracts sloppy with neat petrol. So while helpful when starting cold it's not ideal, whereas proper use of the starter units ( "choke" ) has been proven to be suitable when carbs have otherwise been correctly jetted.

Cheers

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Well my new fuel pressure regulator arrived. I have compared it with my original and can say its not suitable. The casting is very similar, but the diaphragm design is different, but more importantly the spring on the original has more windings, same diameter, thickness and length. So the characteristics of the new one will not work correctly. The adjustment screw on the original is longer. I believe 5 psi is too much for Dellorto. I am talking about early Turbos here. Not sure what the requirements are on later ones. 
I believe the issue with mine was due to a faulty pressure gauge, so am awaiting another one.

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