Ugg10
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| posted on 16/8/17 at 02:12 PM |
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DHLA calc check please
I am looking at putting Dellorto DHLA 40s on my engine having manage to get three (which I can make 2 good ones from) at a reasonable price.
Can someone do a quick check to see if my calculation are correct and if any of the alternatives (from the bits I have) would be OK. Or if someone has
fitted them to the same engine and has settings then please can you let me know. Just need to get it running OK for the mot (Historic blue smoke) and
then run in ready for a rolling road setup.
All comments/help will be gratefully received.
Using Dave Andrews guide - http://www.s262612653.websitehome.co.uk/DVAndrews/dellorto.htm
Engine - Puma Zetec SE, 1.7l (425cc/cyl), 16v, Max power at 6300rpm
Ideal Settings
Choke size - 34mm from diagram
Main jets - choke x 4 = 136
Air corrector - Main + 50 = 186
Emulsion tubes - 7772.6 (425cc/cyl)
Idle jet - 45 (1700cc)
Idle retainer - 7850.2 (suggested for a rich idle then work down from there)
(from "How To Build & Power Tune Weber & Dellorto DCOE, DCO/SP & DHLA Carburettors" Auxiliary venturi 7848.1 for most engines
over 300cc/cyl
The only sizing I don't have is for the pump jets - anyone got any ideas ?
What I have
From my bag of bits I have the following that are close to the above "ideal" numbers -
Chokes - 4 x 33mm
Main jets - 2x140
Air cirrectors - 2x190
Emulsion tubes - 4x7772.5
Idle jet - 3x50
Idle retainer - 3x7850.2
Auxiliary venturi - 4x7848.1
Pump Jets - 4x45
Questions
So, out of that, as a starter for ten, trying to keep costs sensible (will need a refurb/gasket kit and a couple of trumpets as well !),
1) Will 33mm chokes be OK
2) Will 140/190 mains be Ok (they are cheap so happy to change these)
3) Will the emulsion tubes for the larger engine be Ok (£9 each, ouch)
4) idle jet size? (again cheap so ok to replace)
5) any info on pump jet size welcome.
Sorry for the long message but hopefully this has given you enough info to help.
Thanks in advance.
[Edited on 16/8/17 by Ugg10]
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1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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Angel Acevedo
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| posted on 16/8/17 at 02:51 PM |
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I for sure think that 1 mm difference in venturies will not have a perceptible difference.
Bigger main jets with bigger air correctors may arrive you to the same A/F ratio.
Emulsion tubes are a dark scienece or something like that according to Pat Braden, so no guess from me here.
And lastly, I would use whatever pump the carbs are fitted with, as you may adjust with the cam on some models. I don´t have my Pat Braden book with
me, but may check what does the book says.
HTH.
AA
Beware of what you wish.. for it may come true....
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cliftyhanger
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| posted on 16/8/17 at 04:58 PM |
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I had dellortos on my old 1800 zetec.
What i did didscover is there are many types of dellortos as they developed them over the years. Getting matching suffix is essential.
Mine were N (IIRC) and just needed the idle jets opening up a tad. They run on the "idle" jets up to a few thousand rpm, so they should
get you through an MoT.
This may be of assistance too...
http://sideways-technologies.co.uk/forums/index.php/topic/1048-setting-dhla-dellorto-dellorto-float-fuel-level/
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Ugg10
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| posted on 16/8/17 at 05:25 PM |
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Many thanks.
For pump jets I managed to find this - http://oto.to/schematy/gazniki.pdf (Des Hammill book) which suggests 40 for 425cc/cyl (page 76) and also has
the quote about 7848.1 being the most common Auxiliary Venturi. So can probably go with the 45 and see how it goes.
Thanks for the link on setting float heights, useful as well.
The carbs I managed to get are - a pair with the same metal tag of "R5244P" on it, one is complete and the other has a few bits missing
both need a good clean up. A third one with a single cable - over the engine throttle mechanism (nice) and 42mm long trumpets. In very good condition.
All just say DHLA40 cast into the casings and seem to have the same three progression holes.
So, as far as I can tell they are all the same without fully dismantling them (that will happen in a few weeks) and have enough parts to make 2 good
ones from them (with the extra jets and new gaskets) with the exception of the balance bar and a fuel T banjo.
Any more info on how to work out the model would be great.
Should be interesting to see how these go with the VCT on the engine. I have two options here - control it VTEC style (see posts on here from Jenko)
or splash out and buy the the VCT controller from ME. To get it running I can just leave it off and miss out on a load of mid range power/torque and
then work that out later.
Thanks
[Edited on 16/8/17 by Ugg10]
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1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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cliftyhanger
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| posted on 16/8/17 at 07:38 PM |
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from memory the suffix was stamped just after DHLA40, so yours may be the early non-emission type. No bad thing I expect.
Just thought, the spitfire we recently bought has a pair of brand new (old stock) DHLA carbs on it, seem very well jetted and it gets 40mpg on a run
(290 degree cam, roller rockers and flowed head, all Triumph 1300. Expected to be 110bhp! th bloke spent a fortune on the car) Anyway, they are
non-emission carbs.
Re ecu, what ignition? if thinking of a vvt controller and also need ignition, it may be worth getting the me221??
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Ugg10
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| posted on 16/8/17 at 07:57 PM |
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I am looking at the canems ecu. Had a bike carb set from Chester sports cars that originally used the megajolt junior (great kit, bolted it onto a
2.0l zetec, five wires and off I went, 165hp), they moved to nodiz and now use the canems. It is around £300 with basic loom and runs directly into a
coil pack.
Motorsport electronics do a vct controller for the puma engine at around £200 but the canems looks like it can control it in the same way Jenko did in
his Sylva j15 using an omex600, off upto 2200rpm, then on and back off at 5800rpm also off below 25% load. His engine on injection and gsxr throttle
bodies made 155hp with everything else standard.
I have an omex710 but that is overkill for just spark so that may have to go along with my 42mm dcoe throttle bodies. I know it is a step back but in
the Anglia I think carbs will go well. Also want to keep it simple if I can. Will use to get it running and then swap out the ecu I think.
Canems needs crank pickup, coil pack, tps or map sensor and that is about it.
[Edited on 16/8/17 by Ugg10]
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1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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