Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: phil on Friday,October 06, 2017, 10:16:07 AM
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Hello all,
My TC runs fine but after a few starts it splutters and misses, I have taken the plugs out and they are sooty, cleaned them and all is well again, I presume its the mixture?
Is there an easy way of adjusting the mixture (Dellortos), an article somewhere perhaps, or do I need a colortune? I will also get a synchronising tool to balance them if needed?
Thanks
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There are books on tuning Dellortos and Webers on Amazon. I found this on the interweb and it might be helpful: http://www.aircoolednut.com/erkson/ttt/engine/carbs/dellorto.html
What sort of driving or running are you doing between starts? It could be that your idle mixture is set too rich. I would think that your plugs should still not foul so I wonder if you're plugs are too cold.
You should get a synchronizing tool of some kind anyway, but I don't think mis-balanced carbs would be the primary cause of your plugs fouling. Are only certain plugs fouling?
I forgot to suggest that you join the sidedraft central yahoo group.
I don't know about colortune. I've heard good things about them but the plug depth on the TC (and my BDA) might make it less effective. I would love to hear from anybody who has used it on a TC.
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+1 for joining the Side Draft Central forum. Keith is doing some amazing work
As for the colourtune, I did use one on a TC albeit in a +2. There is a cover attachment with a mirror that lets you see the flame even when it's buried deep within the cylinder head. But, a colourtune is only really useful for setting idle mixtures.
Other than that, have a read through the workshop manual too:
http://www.lotus-europa.com/manuals/tcwork/l/index.htm#7 (http://www.lotus-europa.com/manuals/tcwork/l/index.htm#7)
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First, are you using the "choke" to start? Doing so often leads to fouled plugs. Best practise for a TC is to press the throttle to the floor two or three times and then start it. Feather the throttle to keep it running until it warms up a bit.
Carbs are like computers, if they are fed garbage, that's what they give out. So, first make sure everything else is up to snuff before doing anything to the carbs.
I would:
- check valve adjustment (carbs do not like tight valves)
- adjust the timing chain while you are in there
- check compression
- check point gap, timing at idle and total timing at high rims
- air filter clean?
- check exhaust for restrictions
Once that is all good, you can move on to the carbs:
- are they properly mounted? (some flex but not too loose -- see manual)
- jets match specs
- do get an air flow gauge and sync the carbs
- count the turns to lightly seat the idle mix screws. Then turn the screws out the same amount, roughly to where they were. Start the engine and warm it up. Set it to fastest lean idle (clockwise = lean) then out a quarter to a half turn more.
Take it for a run. How is it? Still not right? Then take the top off the carbs and check the float level settings.
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I had the same issue with mine.
The local TVR garage recommended the following
check balance - running a hotter plug - a fuel additive.
all help to burn the unleaded fuel.
Worked for me.
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It all depends. If you mostly drive at five to seven tenths, dropping in a hotter plug may help, depending on what the actual issue is. However, if you drive at 8 tenths and up, say flat out up a mountain pass, a hotter plug may result in detonation.
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Hi Phil,
There's plenty of good advice already given so I can't add very much other than I'm also in the UK and so using the same pump petrol that you are. As John says, check the easy bits before diving into the carbs themselves, at least the ignition set-up and air filter before twiddling with the idle screws.
I changed to a hotter plug a few years ago on both the Elan & Europa because I only drive on the road and there's not many places around here where you can blast along for more than a few minutes without attracting attention. So the hotter plug works for me. I also have Pertronix electronic ignition & maybe that's helping as well.
I do use a colortune but as Rod says, they are mainly about setting the idle mixture. It's easy to see the flame and adjust the mixtures on the TC in a garage, not so much if you're using it outside in daylight. The downside is that if you've only one colortune then it's a slow process, one choke at a time but they do work pretty well - twiddle the screw, watch the flame change colour - low tech stuff.
The best book I've seen on the Dellorto carbs is Des Hammil's book "How to Build & Power Tune Weber & Dellorto Carburettors". It's generic of course but some very good diagrams, photographs and explanations of what goes on inside them. Miles Wilkin's book touches on carburetion in relation to the TC but I think Hammil explains the importance of float heights, accelerator pump jets and how they work much better.
The Yahoo group mentioned is excellent & I'm also a lurker on there, but the talk is mainly about webers and although they look similar there are differences in the way they operate so you might find some confusion if you're new to these carbs.
Brian
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+1 on the "How to Build & Power Tune Weber & Dellorto Carburettors". It is excellent.
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Out of curiosity, what plugs are you using?
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I’m not running a TC.
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Hello all,
I am running NGK BP7ES, they are all sooting up, what would be a hotter plug?
I am getting a colortune and a balancer, I think I have identified the 4 mixture screws (springs around the threads)?
Will give it a good check over when kit has arrived.
Thanks
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Please don't. Please, please, please find someone who is familiar with Dells and have them walk you through properly setting up the carbs.
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I am running NGK BP7ES, they are all sooting up, what would be a hotter plug?
I have also used those plugs but currently have BP6's in both the Elan & Europa. The old Champion plugs referred to in the manual used to go hotter with increasing numbers (N9Y hotter than N7Y) but NGK go the other way. Lower number is hotter.
https://www.ngk.com/learning-center/article/200/how-do-i-find-a-colder-or-hotter-plug (https://www.ngk.com/learning-center/article/200/how-do-i-find-a-colder-or-hotter-plug)
I am getting a colortune and a balancer, I think I have identified the 4 mixture screws (springs around the threads)?
You don't actually need a colortune to set the carbs up although I find it reassuring to see the flame burning correctly and uniformly across all 4 chokes. I'll repeat, if you want to mess around seriously with these carbs then buy Des Hammil's book. You can manage with the workshop manual but it's far easier to relate to photographs of actual parts in colour, which you get with Des's book.
However to get you started if you don't have the printed manual, there's a link to it from this site; http://www.lotuseuropa.org/workshop_manual.htm (http://www.lotuseuropa.org/workshop_manual.htm)
the TC supplement on fuel is about half way down. Scroll through the pdf and there's a sketch which will confirm where the idle screws are and what the base setting should be.
Before you disturb the balance between the carbs or even twiddle with the idle settings, make sure everything else is right (air filter/ignition/etc) because unless someone has messed up the carb settings they are normally fit/adjust/forget items. Put 'em on, use the car regularly and they stay in tune for years.
Back to idle screws - the idle circuit only covers tickover and the start of progression as the throttle opens, so unless your engine is on tickover for long times you might have to look elsewhere for why the plugs are sooting up. If you've still got the problem after setting the idle to it's leanest possible without affecting progression as you open the throttle then come back and we'll think about other options.
Brian
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If they are all sooting up evenly, then it is unlikely to be balance. so check ignition first including strength of spark! What plugs are you running because as is already mentioned you probably want to run a reasonably hot plug with the type of driving you are doing.
On a side note carbs will slowly drift out of balance and any disturbance of the carbs will require a re-balance. Use a synchronometer unit (used to be Guyson I think). it is a good investment as it's is so easy to do you and won't regret it.
Then if you are still sooting up you will need to dig deeper into the carbs, has anyone messed around with the jetting?
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Agree with all the above. Try BP6 plugs, they burn a little hotter, and your sooting may disappear. Works on my Elan and Europa TC.
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Agree with Tony my Elan and Europa had the same problem on 7s changed to 6s and the problem has never reoccurred
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Hello all,
I am assuming a BP6 is the same as a BP6ES?
Thanks
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Hi Phil,
BP6ES is the plug I have fitted, the "E" refers to the thread length on the plug, "P" for the extended insulator aspect of the design. BTW, there are some interesting responses to the plug choices, I didn't realise so many others were also running hotter plugs as well.
Brian
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I'm running 6's and NGKs. running 6's in my Westfield ford crossflow, 7's will cause starting problems/fouling if I'm not thrashing it.
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Hello All,
I have now fitted the new plugs and gave it a run, the front 2 cylinders were still sooting up, I have now used the colortune which showed that they were running too rich, I have adjusted them and also used the carb balancer, again they were both quite different.
It now starts on the button and all seems well.
I have just received a cork gasket from SJS for the airbox as it was missing, what is the best way to hold it in place whilst fitting it please?
Thanks
Phil
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Now that's great news Phil, it's good when someone feeds back how they got on and solved the problem. From what you say about imbalance it sounds like the carbs have been off and replaced without checking balance at some point.
I must admit until you mentioned it I didn't realise there should have been a gasket on the airbox, I've never seen one on my car.... :-[
For any gasket that could move about during fitting I usually put a dab of Hylomar or similar to hold in in place whilst tightening up. I don't think I'd use the Instant gasket type sealants there, at least not without checking for petrol compatibility.
Brian
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Double sided tape (trimmed to gasket width) on one side of the gasket is what I used.