Carb Service Kit - Covid Boredom Casualty

[DaKa]

Hoping that you're all staying safe and well and not too bored.

With time on my hands, I decided to apply the dellorto DHLA45 carb refurb kit that's been on my garage shelf for several months.

Although I was extremely methodical and content that I did everthing perfectly, the car won't start, so I'm now suffering an indirect effect of the current lockdown having attempted a job that I would have normally left to someone more capable.

Perhaps I've tightened down something that should be open or perhaps I have a fuel air block?

I closed and then opened the mixture screws 6 half turns, and then closed completely (although not at first) the air bleed screws (but I don;t think closing these fully can be right? trying to read the technical guidance in the manual). It sounds like its not getting fuel, and yes, I've given the floats plenty of time to fill up.

The only thing I wasn;t sure about was the 2 electric wires connected one brown and one black - I may have got these mixed up, but does it matter when it comes to starting?

I only tried to fire up this evening, so will find time tomorrow to try again, but any tips on the many adjustments on these CHLA45 carbs would be welcome. Can someone confirm if the air bleed screws should be closed to start with?

Also, would it be right to say that everything inside the carb float cover is done up tight? I do hope that I don;t have to take it all off again!

Thanks

 

 

 

[AndyPG]

32 minutes ago, DaKa said:

the car won't start

Hi Damien,

Is it not even firing while cranking?

Or does it fire but not run?

Might be worth a quick look in the top to see if the float chambers have fuel in.

Maybe re-check the float valve and floats are correctly assembled. Float height set correctly.

Choke cable connected and working.

Fuel pump runs?

Did you set all adjustable screws exactly how they were originally, ie count the turns to shut.

Andy.

Edited April 13, 2020 by AndyPG

[DaveyT]

Hi Damien, 

there has been some confusion in reading the manual in the past as to whether it’s 6x1/2 turns, or six AND a half turns...

my N/A had a baseline of the latter, and ran both sweetly and economically.

whip the tops off the carbs to check fuel presence/ level then Adjust as necessary using the following:

https://www.theapplebyclan.com/Richard/Tiger Super6/Useful info/Dellorto/

oh, and I made a tube manometer about 1.3m tall using AtF as the fluid to balance the carbs ( the dial vac gauges I bought were shiote) which is about 15 times less dense/more sensitive than a mercury equivalent or Mogan carbtune, and cost about a fiver to make.

godd luck!

 

[DaveyT]

On the last line of you original post, yes, everything should be done up tight, but I highly recommend that you take the tops off to measure the actual fuel level in the float bowls using the above guide (27mm down on average from the top of the centre stack)

Terrified me at first, but It is a pretty essential step towards smooth performance running, and nowhere near as challenging as I first feared.

Without it, many seem to suffer from misses and carb flutter at certain points in the rev range.

[910Esprit]

Yes, without a manometer or a good ear and a plastic tube, I'd fully close the bleed screws.  Their purpose is to allow each choke within a carb to be finely matched/balanced to the other choke, but they are not material to your non starting issue.  However. you will definitely need some kind of balancing device before you can expect the engine to run sweetly  (EG the balance of the 2 separate carbs is critical to good running)

Yes, everything inside the top cover should be 'done up tight' - But only tight enough to avoid leaks, or screws backing off due to vibration.   No more than that, or you risk chewing things up.

If an X180 is a carb turbo variant. I'd suggest no more then 3.5 full turns as a starting point.  

Are the plugs wet or dry?  Also consider that you may have done something that is dumping too much fuel in the engine, rather than too little.

Could you have disturbed anything else?  EG is it still sparking when cranked?

You could run initial tests with open chokes, you can then check for the presence of fuel, accelerator pumps function etc.   But if you do  follow that approach. be mindful of spitting back or fire!!!

 

 

 

[DaKa]

Thanks I'll check all of the above later today.

So in summary, Air bleed screws can be closed (but needed for tuning/balancing carbs) and mixture screw could do with another half turn making it 7 x half turns from closed starting point.

Last time I did the same on my Excel engine everything was sweet afterwards, I didn't adjust float level then and didn't this time, so will check the link above as this may be my problem having replaced the parts here. P.S. I noticed a tiny little plastic cup (No.23 in the image) which I retained but wonder why such a small part is also not in a service kit?

Also appreciate the suggestion to remove top of float chamber, as I was going to disconnect the fuel pipe and check if it's pumping, but that would have only served as a fire risk and still wouldn't tell me if petrol was getting into the chamber - I guess that I could put some in directly into the chamber to see if it fires up.

NOTE: I don't have a choke cable? I did on my old Excel, same carbs, but assumed it had been updated? I still give it a few pumps before starting and it appears to adjust automatically (e.g. revs a bit stronger at first and then idles back when warmed up) - so I'll take some more pictures to post if there is nothing shown in the new pics as I'm curious now.

NOTE: It doesn't fire up and then stall, it just turns over without any firing - like the plugs lack spark and/or fuel, so I'll double check that I haven't accidentally pulled a cable out somewhere once I know there's fuel in the float. I also assume the 2 x wires connected as shown do not affect starting.

Thxs

 

P.S. Thanks Dave, but your link to adjust float level is a secure link I can't access?

https://www.theapplebyclan.com/Richard/Tiger Super6/Useful info/Dellorto/

[DaveyT]

Sorry, the link should be accessible, search for sideways technologies if this doesnt work...

http://sideways-technologies.co.uk/forums/index.php?/topic/1048-setting-dhla-dellorto-dellorto-float-fuel-level/

The appleby link is available off there I think. I’ll try and post the text separately.

on the mixture screws, IF yours is an NA, then I’d try 6 full turns, and then an extra half (13 x half turns) per my eventual settings (I also had a note of the settings at this sort of level before I stripped the carbs).
I did try 3 turns first, and like yours, mine wouldn’t fire at that level.

[910Esprit]

From the top cover, I see it's an NA, so try Dave's suggestion.    I cant quite work out what those wires are connected to, but looking at them, I assume they are just the carb earth leads, so should not affect your starting issue.

[DaveyT]

Link not working here now either. Was ok at 4am, so maybe keep trying?

best I have here, unless I can send you something on messenger / fb?

 

 

[jonwat]

1 hour ago, 910Esprit said:

I cant quite work out what those wires are connected to, but looking at them, I assume they are just the carb earth leads, so should not affect your starting issue.

Isn't that the throttle Jack, raises the revs to prevent stalling when the air con is on? 😀

[910Esprit]

Sounds plausible! 

[jonwat]

17 hours ago, DaKa said:

 It sounds like its not getting fuel, and yes, I've given the floats plenty of time to fill up.

So you could hear the SU pump ticking while they filled then? 😀

[DaKa]

Crossing my fingers didn;t work, so as suggested I opened the mixture sctews a few more turns and when still not firing I removed the float cover and found it was bone dry inside.

I guess this means the newly fitted No.13 above is not wroking, or, I have a problem with the fuel getting to the carbs.

I have an in-line filter just before the carbs and I can only see a slosh of fuel in the lower half. I can hear the pump running (its always been noisy) and am thinking that if I disconnect the pipe again at the filter and while directing it awat from the rear of the car see if its pumping fuel when the ignition/pump starts. I prefer to try this before removing the floats again and checking nothing has fallen out of place.

Am I right in thinking the small plastic part 23 is a tiny filter, or a block? I guess it could have fallen out of line as I screwed in the new service part 13? 

Although I had a problem a while back with the drivers side fuel pipe blocked, I have flushed the gunk out twice now, so unlikely to be a physical block on both sides, but I guess it could it be an air block?

[AndyPG]

24 minutes ago, DaKa said:

I removed the float cover and found it was bone dry inside.

Hi Damien,

This was the first suggestion in your first reply.

Next, remove the fuel pipe from the carbs and see if you can blow through the fuel inlet into the float chambers.

If you can, the blockage isn't there.

Now put the end of the fuel line into a petrol can and activate the fuel pump. If fuel doesn't come out, work your way back along the connections (filters etc) until you find the blockage. May even be the fuel pump faulty.

Andy.

[DaveyT]

Some trials maybe before you take the fuel pipes off...Mainly as suggested above but...

does the pump run for a while, then stop? If so After how long?

did you disturb the solenoid shut off (in line past the filter on mine), and is it connected up properly? I made the mistake of painting mine and the body then failed to earth...you should hear it click when energised. Could one of these wires you weren’t sure about be the exciter for that?

I don’t recall seeing part no 23 in mine, and I have no photos showing it..does it have a description?

 

[DaKa]

It's officially - I'm a numpty that is in need of stronger glasses 🙂

I disconnect the fuel pipe at the filter and connected a pipe from it into a petrol can and the pump was clearly working fine when engine ignition on.

Blowing down the pipe towards the carbs didn't to much so I removed the float covers.

I attach a picture of the old versus new (on the right) No.13 part that houses the pin so you can see what No.23 looks like - it's clearly a final ultra-fine mesh filter. It wouldn't sit properly in my new replacement No.13 part, so I had to either put back in the old or remove - I opted to remove for now but have kept for next time.

It was when I went to re-attach the floats that I noticed my stupid error!

When I took off the float cover first time and removed No.41 (pin that hold floats in place) it all came apart - with my bad eyesight I didn't realise that there was a slot that had to be hooked into the new needle/pin as shown in the other image - Doh!

I had just simply placed it underneath and consequently it closed the pin instantly.

Now running well (and I've learned something). 

So although a little embarrassing to have shared, perhaps it will save someone else's blushes.

The Forum feedback above saved me a lot of time - appreciated.

 

 

[AndyPG]

Good to hear you're sorted.

Andy.

[DaKa]

And finally to finish things off, I found the twin carb initial start setup and tuning explanation on youtube below perfect for my understanding and level of requirements for my N/A car.

 

 

 

Although slightly different carbs here, the mixture screws, air bleed screws and airflow balancing are all easily understood.

[DaKa]

Not quite final yet, when completing the refurb kit I noticed one of my 2 float covers had slight damage where the pin securing the floats was damaged on one side (obviously the previous owner punched the pin out with a sledge hammer).

I can see some 'Carburettor Top Cover' on SJS circa, £66 which isn't too bad, but whenever I enter my car build version on SJS site nothing appears! Presumably they are all the same or are N/A DHLA45 carbs different on other models?

Looking elsewhere, they refer to DHLA45 'later' or 'early' carburettor float covers - what do I have?

[DaveyT]

I think the tops may be different to the turbo versions:

the gasket for under the plastic cover, supplied in the refurb kit, is different, so not sure whether the Ally parts are identical. 

[MikeJ]

H

23 hours ago, DaveyT said:

I think the tops may be different to the turbo versions:

the gasket for under the plastic cover, supplied in the refurb kit, is different, so not sure whether the Ally parts are identical. 

Hi, I think the tops are different for the turbo, they connect to the plenum to allow the carbs to be pressurised.  

Mike

[DaKa]

Can anyone tell from my posted picture above whether I have an early or later model DHLA45 float cover.

I also found a broken spring No.71 on the diagram in the following link - it had snapped in the middle and therefore not as efficient as it should be.

https://www.dellorto.co.uk/product-category/dellorto-car-carburettors-parts/parts/dhla-parts/

I've even airflow though all 4 venturi and have now tuned to make the best of things - overall I'm pleased with my efforts, acceleration is smooth with no misfire or spit back, but I do have a hiccup when idling along the road at say, 30-35 mph in 4th gear - not sure if that means too much or too little fuel mixture and not an issue when the revs are higher same speed in 3rd or 2nd gear?

When I get the replacement parts, I'll do it all again.

[DaveyT]

Couple of pics from an ‘82 ( before stripdown) in case it helps black cover already removed

[DaKa]

I could spend £100-£150 on replacement parts and get my carbs fixed properly, or, I could consider buying new and selling my existing. (I bidded recently on ebay for a single DHLA45 less venturi and it went for circa £170 - so I could get back perhaps £300+ selling my old pair?).

I'm tempted by a genuine matching pair of original lotus new/old carbs specific to the N/A X180 but perhaps from a slightly later model.

Can any confirm from the pics?

Also is the mixture adjusting screw blanked, or, being newer does it need a specific tool to adjust?

[DaKa]

Sorry to ask again, but does anyone know why the mixture screw on these New/Old Carb images doesn't have a flat head screwdriver adjustment?

I'm asking again because I've now bought these and await delivery - I guess I'll soon find out.

Item 60/61/62 on the diagram shown on the link suggest a screw adjustment as with my current carbs:

https://www.dellorto.co.uk/product-category/dellorto-car-carburettors-parts/parts/dhla-parts/

I've been informed that it could be an anti-tampering plug on originals that affected warranty if removed?