Hello Lotus fans.

 

I'm hoping you might be able to grant me some knowledge on getting my Esprit 1989 turbo running sweetly again. I've had the car since the start of the pandemic and only driven a handful of times. Bit by bit I'm working through its faults: replacing the alternator, wheel bearing, bushes etc. 

 

I noticed a strong whiff of fuel whilst driving and saw a big fuel leak when I was changing the oil. This lead me to believe that the carbs needed an overhaul as they hadn't been done in years, yet in hindsight I think the leak was coming from a perished fuel hose.

Anyhow, I've rebuilt the carbs with a kit from Southwest Lotus and Eurocarb fitted the  spindle bearings and checked everything. I've fitted a new throttle cable and now need to balance everything.

I've taken my guidance from the Dellorto and Webber tuning manual. The car now starts (3.5 turns out on the idle mixture screws). I've got a synchrometer tool ready to balance.

I've read a few posts on here regarding the colourtune tool. Is this worth getting?

So where do I start? Get the engine warm, get the idle set right on the main carb, get the second carb (airflow) balanced to the first. Other than the idle mixture screws and throttle idle screws, what else needs adjusting?

Any help greatly received. Based in Herefordshire. 

Excuses the gold in the engine bay. When I started the air box and turbo pipe were also gold! Also, excuse the amount of yellow!! Not my taste; I'll be working on this! 

Edited March 27, 20223 yr by Rob Warren
Missing text

The other key 'balancing' adjustment is the air bleed screws on each choke, these compensate for minor airflow differences between each choke, but make a big difference to idle quality.   I would personally use a device that can monitor all 4 chokes simultaneously,   such as a Morgan Carbtune.    The process is detailed in the service notes.   Maybe someone will scan you the page?  (I cant).   The order you have described above is not correct.

Fuel pressure and pump jet operation should  be checked too, but you can set your linkage/balance first.  3 1/2 turns sounds OK for initial setup.   I'm not a particular fan of Colourtune, although I do have one.   I prefer using my nose and looking at the sparkplugs!    

Step up @johnpwalsh

 

Set the accelerator pumps with rig so all deliver 7.5ml with 20 pumps.

Close all the air bleed screws only nipping.

Close the mixture screws and open 3 to 3.5 turns

Make sure all the butterflies are shut then just touch the centre adjuster/carb joiner.

Wind in the idle screw so all butterflies just open.

Blank the vacuum off take on the inlet manifold.

Start the engine and set timing to 9-10 BTDC.

Get the car to idle as low as possible then adjust the mixture screw for best vacuum on all cylinders.

Reset idle so low as runs without stalling.

Now open the air bleed screw on the cylinder with the highest vacuum on each carb so it matches the weaker joining cylinder.

Now you can adjust the centre shaft joiner to level the carbs.

Adjust the idle.

Repeat the process again getting the best vacuum on each and repeating as this allows the carbs and engine to settle.

Remember only one air bleed screw should be open on each carb.

Run the car then check the plug condition so you aren’t running to rich, should be a nice tan brown colour.

If not and too black you are running over rich, a little black is fine as these engines run better a little rich.

 

As Steve says get a Morgan Carbtune, I, not a fan of the colour tune either.

 

Dave  

 

You need the Colortune to correctly set the idle mixture & read this

But before all the above, 

check,  set ignition timing

check, set float valves

And finally, try to find a local MOT garage that are happy to work with you.   It can be a balancing act to get the emissions within limit on an older car - for you 3.5% CO2 I think.  If the car is otherwise tuned well, a small trick is to increase the idle speed until the CO2 falls with limit....   😉

Thank you to everyone for a quick response.  I've purchased a morgan carbtune manometer.  and a new timing gun tonight.

 

If possible, I'd rather not take the carbs off again to check the accelerator pumps after replacing all the gaskets to the manifold and trumpets.  Is there another way to check?

Can I assume its best to time the distributor first (ease of access), then add the air box and turbo pipe before proceeding to use the manometer?

Thanks again.

 

Rob 

yes, set your timing before doing anything to the carbs.   NB set according to 'the book' which varies from model to model. 

Some folk reckon you can set the pump jets by the number of threads showing on the activator rods.  I guess it may be better than nothing, but it wont be accurate.   Only way is off the car using a test rig to measure how much fuel is pumped  (see Dave's version above above).    However, don't lose any sleep over it just yet, you can do all your other adjustments first and see how it runs. 

Much good advice above with which I am in agreement. Yes, be certain first of ignition timing, valve clearances and overall sound state of affairs in the carbs. Watch out for issues with fuel pressure, particularly with a Turbo, as discussed elsewhere lately in TLF. Confident in these critical fundamentals then concentrate first on carbs balance at idle before looking at pump or other jets.

Cheers  

Fantastic stuff. I'll update the progress 

Just a side note - there are some Alfa sites that may have more info - as they also used Dellorto carbs (lots of people in EU/USA race these vehicles)  I'm sure Google can assist here ....   with my '85TE - getting the two carbs balanced first before anything else was attempted was a revelation. It took me about 4 attempts, as engine overheating became a concern whilst work was in progress. All this was done with a Morgan Carbtune - indispensible - as I got all 4 carbs balanced to within 1mm of each other. I had tried to skip this on prior attempts, and fixing popping/sluggish acceleration etc. all went away.

Good luck with yours  - it's a great feeling when it all works. 👍. 😃

Yes, getting the carbs in balance is crucial and deficiency in that will show as popping on overrun, plus bad tip-in behaviour. Funny thing is that balancing can be more straightforward than many assume, and not in need of the assorted contraptions sold for the purpose. Quite simply, one can adjust out the subordinate carb whilst setting the master carb to just closed, then bring in adjustment of the slave to match by way of the connecting linkage. That gets one nearly there in one fell swoop. Balance is highly influential at idle therefore more easily perceived in running terms, and it is at idle where the synchronising gadgets ( notably Uni-Syn ) will foul up the proceedings due to airflow constriction.

Cheers

Good post, I'm getting close to needing to tune my carbs, and it's the only thing that worries me because there's so much black magic. I'm pretty sure I have a flow meter with 4 indicators and color tune somewhere 

I really hope you replaced the accelerator pump diaphragms

Yes I replaced absolutely everything - even the butterflies as they were bent.  Manometer and new timing light has arrived.  Just need to get some time on it now.

Just make sure everything is air tight, especially the servo vacuum hoses

Ok I'm back in business. Had to shelve this project with a house move and a garage being built. It's now alive and starting well. Tdc markings were faint so I used the screwdriver trick on cylinder 1, found it and made it clearer. Timing is showing 5 degrees btdc. This is at warm idle 950rpm. Distributor looks difficult to get at but I can  see a bolt with a flat screw driver head at the base by looking through the gap on the inlet manifold. Will this loosen it the distributor or is there something additional that needs releasing? Thanks folks. 

Forgive the interior. Will be dyed black once I fall in love with it again. For now I'll keep my sun glasses on.

 

13 hours ago, Rob Warren said:

Will this loosen it the distributor or is there something additional that needs releasing

You need to slacken the distributor clamp bolt, part number seven.

Thanks, can nut number 5 remain untouched?

2 hours ago, Rob Warren said:

can nut number 5 remain untouched?

Yes, 5 is what bolts the clamp to the block & only undone to remove the distributor from the engine without losing the timing.

Edited August 12, 20231 yr by jonwat

Today I managed to balance the carbs with a Morgan carb tune with good results. I haven't as yet touched the idle mixture screws since turning them 3.5 turns out on the first start up. Prior to balancing (I haven't checked after) the plugs were getting sooted up quickly and needed a clean every other time the engine was started. I haven't got a gas analyser and I've got a few bits to do before it goes to MOT. Is a colourtune device worth a purchase to improve this? Thanks all.

If all your plugs are similar, sooty and you can smell fuel in the exhaust, I'd just turn your idle screws in by 1/2 turn for now.  Colourtune will provide similar info visually, but not sure it will tell you too much more.  @jonwat Seems to rate them highly?

Edited August 29, 20231 yr by 910Esprit

3 hours ago, Rob Warren said:

Is a colourtune device worth a purchase to improve this?

Yes, it allows you to set the idle mixture accurately for each cylinder by seeing the  colour of the flame as the mixture burns inside the cylinder.

I've purchased one so when it lands I'll report back with the results