Lotus Elan

Setting up Dellorto’s

PostPost by: westiman » Tue May 25, 2021 2:50 pm

Hi all.
I am hoping a club member will take pity on someone who has bitten off more than he can chew. I have recently had my Dellorto’s refurbished and have now re-installed them on my 1973 Elan Plus 2 S 130, but I am now having trouble setting them up again.
They were not that good before the rebuild ( hence the rebuild) - so to try and be sure I got workable carbs that I knew I hadn’t messed up in the rebuild, they were sent to Eurocarb in Reading for the refurb.
They have been returned with what I understand are baseline settings ( very baseline), whilst the car starts ok I just cannot get them synchronised etc.
I am in Burgess Hill (West Sussex) Nr Brighton, and would be grateful if someone had the time to perhaps pop along and have a look at the problem with me with a view to getting the car back on the road! Hopefully I’ll have just done something stupid and whoever can diagnose what that is! Happy to cover any costs incurred.
If you are happy/able to help, please pm me to make arrangements.
Kind regards
Andy
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PostPost by: jono » Tue May 25, 2021 4:22 pm

Hi Andy,

You really need a Morgan Carbtune to get you started - well worth the investment regardless.

Do you have air bleeds to allow barrel to barrel balancing on each carb?

Hopefully some kind soul local to you will be able to oblige - if they've been properly refurbished they should not be too difficult to set up

Jon
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PostPost by: westiman » Tue May 25, 2021 4:56 pm

Hi Jon
Thanks for coming back to me. I had rather hoped it wouldn’t be too much of a problem but this car fights me all the way.
I will look out for a Carbtune.
I have a synchroniser and a manometer, but put them on the carbs and the synchroniser says the rear carb is flowing most air and the manometer says it’s the front one flowing most air. Either way the lever/screw set up to balance the carbs won’t level the flows up.
Once again thanks for your help.
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PostPost by: jono » Wed May 26, 2021 6:51 am

Andy,

The beauty of the Morgan unit is you can see exactly what each barrel is doing simultaneously in response to every change you make as it uses the vaccum ports on each throat and you have a manometer for each one

Try this as a resource (check out the section on tuning DHLA's):

http://www.dvandrews.co.uk/
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PostPost by: alan.barker » Wed May 26, 2021 7:05 am

Andy,
buy a new Morgan cartune you will never regret it.
Carbs balanced in 10 minutes and you don't need to remove Airbox. Very nice bit of Kit, spot on. Worth the money easily.
Used on my 1973 +2S130 and my 1972 Elan Sprint.
A no brainer for sure.
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: Andy8421 » Wed May 26, 2021 9:21 am

westiman wrote:Hi Jon
Thanks for coming back to me. I had rather hoped it wouldn’t be too much of a problem but this car fights me all the way.
I will look out for a Carbtune.
I have a synchroniser and a manometer, but put them on the carbs and the synchroniser says the rear carb is flowing most air and the manometer says it’s the front one flowing most air. Either way the lever/screw set up to balance the carbs won’t level the flows up.
Once again thanks for your help.

You should be able to get this done with a synchroniser without having to buy anything else. Assuming that you are referring to a synchrometer like this:

https://www.merlinmotorsport.co.uk/p/ste-carburettor-synchrometer-sk-type-syn001

Depending on where you are fitting your manometer, you can end up with manometer readings which are inverse to air flow, so the highest flowing barrel has the least amount of inlet vacuum. I would just stick with the synchrometer if I were you.

One area that can cause problems is if you have done away with the standard airbox and fitted separate carb mounted filters. This allows the carbs to move relative to each other and you will never get the readings to match.

Good luck.
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PostPost by: alan.barker » Wed May 26, 2021 10:01 am

True,
You can do it with a Synchroniser but you could also balance using a length of garden Hose and listern.
It's a personal choice for you to choose.
The good thing with Dellortos they have the Vacuum Ports already.
Have fun
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: westiman » Wed May 26, 2021 1:30 pm

Good afternoon gentlemen.
Firstly thank you for all the help you have provided which is much appreciated.
Jon - I had a look at the Morgan Carbtune last night and realised that i already a similiar tool - called a Carbtune Pro.This was the manometer I had been using (unsuccessfully) to try and back up the synchroniser readings I had been getting. As an example the synchroniser had given me flow readings (from rad back to bulkhead) for each venturi of 2.0/1.2/4.0/1.1. The manometer readings had at least been consistent for each carb with the carb nearest the rad showing (from memory) 18hg for the two venturi in the carb nearest the rad and 30hg for the two venturi in the carb near the bulkhead.
My next question is therefore (and I probably know the answer but please humour me) how close do the readings have to be? I guess the ideal is identical, but is there an acceptable level of variance in the readings that will still provide an efficient engine?
I also already had a copy of the Dave Andrews guidance for tuning delloto's and a workshop manual. So it would appear I have the tools and information I need to do the job, but lack the skills to use them effectively!.
Andy - yes I have the synchroniser that your attachment refers to. Thanks for the heads up re the possible problems with the manometer readings but I'm hopeful that having the air bleeds in the carbs would mean that there should not be such problems. If my confidence in this is misplaced please let me know! I have the bog standard airbox set up.
Alan - I do have much garden hose about and am aware that certain skilled people do use it for this purpose. Indeed my ex brother in law, who is a trained mechanic, is one of those people. Sadly though I do not have the 'ear' required for it. I am not deaf by any means but when i have tried it I have rarely been able to tell the venturi apart. Its also a problem when I try to set the mixture screws. I have got away with it in the past by getting as close as I can and then visiting my brother in law for the final adjustment. But as he's 'ex' now I fear that avenue is now closed.
Anyhoo, thanks again for all your help. If I could just have opinions of permissable flow variations per my comment above I would be grateful.
I look forward to many more 'happy' hours in the garage - probably leading to many more questions to pester you with!
Take care.
Andy
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PostPost by: alan.barker » Wed May 26, 2021 1:46 pm

The good thing with the Morgan Carbtune is you have 4 columns all next to one another. So instant to compare at same time.
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: Donels » Sat May 29, 2021 8:32 pm

Did you use new seals when you refitted the carbs? Have you got them tightened correctly such that you have no air leaks?
Before you invest in new equipment I suggest you check the basics and then use just one of your air meter or manometer. Also just check that the butterflies on each carb are opening together, I know they have been rebuilt but it doesn’t mean they’re correct.
Elan +2
Elise mk 1
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PostPost by: westiman » Sun May 30, 2021 9:25 am

Hi Donals
Thank you for your thoughts on my problems.
I have checked the butterflies are seating although, yes, I did think the butterflies should be ok because of the rebuild.
I’ll probably need to take the carbs off off again to be 100% although that’ll be disappointing because as you will know getting the Thackeray washer gaps correct is a real pain, but if it must be so it must be so.
The rubber seals are new.
As I say thanks for your helpful suggestions, they are very much appreciated,
Cheers
Andy
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PostPost by: billwill » Sun May 30, 2021 1:58 pm

westiman wrote:Hi Donals
Thank you for your thoughts on my problems.
I have checked the butterflies are seating although, yes, I did think the butterflies should be ok because of the rebuild.
I’ll probably need to take the carbs off off again to be 100% although that’ll be disappointing because as you will know getting the Thackeray washer gaps correct is a real pain, but if it must be so it must be so.
The rubber seals are new.
As I say thanks for your helpful suggestions, they are very much appreciated,
Cheers
Andy


Too many owners read too much detail into the carb o-rings gap. It isn't intended to be precise. you just tighten them until you feel the o-ring compress a little amount.


I just do it by feel; you need to be just able to rock the carbs a small amount, say 1-2 mm, after they are on.
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
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PostPost by: westiman » Sun May 30, 2021 6:05 pm

Thanks for the info bill will.
As far as I can tell all my clearances are just over 1mm so hopefully that’s ok.
I have made some progress using the manometer which, with the engine up to temp and settled gives readings (cylinder 1 to 4 in CHF) of 16/20/20/16. I wonder if the lower readings on 1 and 4 are because of the vacuum take off for the light pod and brake servo.
After some mixture adjustment, the engine is still rocking a little (probably my duff hearing as explained earlier) but hopefully it good enough to get somewhere for the final adjustment.
Many thanks again for your help.
Regards
Andy.
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PostPost by: lomh 13 » Sun Jul 25, 2021 7:30 am

Hello all
I 've bought a 1972 Plus 2 S 130 equiped with two Dellorto 40 DHLA.
At low RPM, the car seems to run on 3 cylinders and as a rough running until 2500 RPM.
Had a closer look to the carbs that have been cleaned ans tuned by the PO and I have two questions.
As you can see on the picture the holes (idle bypass screw) with the red arrows are not closed.
And the holes withe the blue arrow (vacuum tap blanking plug) are closed by a screw witch seems to have a little hole.
Is this setup correct ?
Image

Thnak you for your advise
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PostPost by: westiman » Sun Jul 25, 2021 10:26 am

Hi Lomh.
It looks the same as on my Dellortos (I have checked photos of my carbs as the real ones are back at the refurbishers for a second try).
I have used the vacuum taps on mine as take off for a manometer set up, and whilst the plugs look like they have a hole from the top, from memory there are no exit holes in the plugs when you take them out.
The bypass screws are uncovered on mine too.
I hope that’s some help/comfort .
Regards
Andy
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