Lotus Elan

Difficulty cold starting

PostPost by: JonB » Tue Dec 12, 2017 9:11 am

Soon I will have the front end back together. I have to say, it's a PITA leaning over the wings to fiddle with the carbs when it's a foot in the air (on stands). I could run it to warm the engine easily, already did in fact (to change the oil), but reaching the spark plugs is difficult right now (and forget about peering down a Colourtune neck).

I need to read up on these carbs. Is the mixture screw just for idle, or does it affect other parts of the carb functionality (or are there other adjusters)?
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PostPost by: alan.barker » Tue Dec 12, 2017 9:30 am

The mixture is just for idle.
For the balance i use a carbtune which is 4 columns and there are vacuum take offs already with dellortos.
That means you can leave the airbox in place and balance is done in 5 minutes + it's spot on. Easy diy job.
When i replace the "O" rings on the inlets tracks i put a little silicone GREASE MS4 so they settle into place well.
If you use a 1/4" drive socket with extension you can get the 2 carbs off together in about 10 to 15 mins very easy.
I have also fitted a simonbloc to replace the points which fits nicely inside the dizzy on my Sprint.
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PostPost by: XR40 » Tue Dec 12, 2017 10:28 am

Alan

Please could I ask what make of 'carbtune' device you use? I have been looking to get a carbtuning device but don't know which is best.

Thanks
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PostPost by: alan.barker » Tue Dec 12, 2017 11:37 am

"Morgan CarbTune II with 4 Columns" i have found is the best with a pouch to put it in 100%
I think it's about ?59.
If you do a google you will find the site easy
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PostPost by: XR40 » Tue Dec 12, 2017 2:24 pm

Thanks for that Alan. Very helpful.

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PostPost by: JonB » Fri Dec 29, 2017 8:19 pm

alan.barker wrote:When i replace the "O" rings on the inlets tracks i put a little silicone GREASE MS4 so they settle into place well.
Alan


Knew I forgot something! No grease.. but my O rings were a tiny bit too small for the gasket thing, kept popping out. An adjustment to my fitting technique sorted that, plus careful fitting to the cylinder head. Unfortunately, this made no difference (to the poor running) but I did discover that I'd inadvertently closed the butterflies on the rear carb (by tweaking the balancer). I used a Syncro Tune (hand held flow meter in effect) on the inner barrels to balance the carbs against each other. No problems (but it is still running poorly).

Meanwhile, it seems to be better at starting. I am using a little choke and NOT pumping the throttle.
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PostPost by: alan.barker » Sat Dec 30, 2017 8:23 am

Imho Please NO CHOKE on Dellortos
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PostPost by: JonB » Sat Dec 30, 2017 9:29 am

Hi Alan

I acknowledge your view but the car will not start without choke. If I use the other method - one squeeze of the throttle then start - it floods every time.
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PostPost by: alan.barker » Sat Dec 30, 2017 9:59 am

Are the accelerater pumps working correctly and the diaphragms in good condition. I have known the pivots for the pumps under the carbs to be seized and not moving freely.
Have you fitted a complet gasket set including the diaphragms.
For the float valves many people prefer the "Viton" ones which seal easier.
You could check to see if the chokes shut off 100%.
There are also non return valves in the Dellortos with very small ball bearing which need to be nice and clean.
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PostPost by: JonB » Sat Dec 30, 2017 10:04 am

I can't answer those questions because I have not removed / stripped the carbs. I have the SpeedPro book on Webber & Dellorto carbs which I'm reading at the moment. I can see a strip down & rebuild in the not too distant future, that's for sure.
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PostPost by: alan.barker » Sat Dec 30, 2017 10:39 am

When i bought a 1973 +2S130 it had not run for 23 years and one of the accelerater pumps had seized solid.
If you look under each carb you can see the pivot for the pump. This must move freely.
When you open the throttle the pump should move. The pump on Dellortos is activated by a light spring and is not a solid mechanical action from the from the butterfly spindle.
If one of the pump pivots is seized when you open the throttle the engine will be very very lumpy :roll:
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PostPost by: JonB » Sat Dec 30, 2017 11:54 am

Ok, I've determined the timing was out and carbs not balanced right. Have sorted that and we'll see what happens on the next cold start. That said, on the test run I had no lumpy running or acceleration problems, so I am reasonably confident the pumps are ok.
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PostPost by: el-saturn » Sat Dec 30, 2017 3:27 pm

i guess there's too many fiddlers amongst us: once everything (i mean the entire chain from leads to points, jets etc..) is done properly you'll have NO fusses: mine starts, after a tiny bit of juice, within 3 revolutions whether 0? or 30? -- no differnce!!! fiddlers like webers and webers like fiddlers! as we used ta say: get your shit together -- its real simple!! sandy
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PostPost by: JonB » Sat Dec 30, 2017 4:38 pm

That was constructive... :roll:
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PostPost by: William2 » Sat Dec 30, 2017 6:04 pm

Hi Jon, Dellortos are designed such that the choke should be used for cold starting and you should not pump the accelerator pedal. I think it even says this in the owners manual. My elan always starts well using full choke and then it should be pushed in as soon as possible to minimise bore wear.
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