dirty diamond Posted April 21, 2012 Share Posted April 21, 2012 Hi all, just put the dhla 40's back on my westy after rebuilding them and installing the rebuild kit. The westy was recently bought as a non runner, it now runs but idles over 2000revs then under 2000 then over again. I think the floats must be set wrong but have no idea how to set them correctly as I had no instructions when I rebuilt them. Any advice, diagrams, measurements etc. would be appriciated, regards DD Quote Link to comment Share on other sites More sharing options...
markcoopers Posted April 21, 2012 Share Posted April 21, 2012 So it is hunting up and down around 2000rpm? By how many rpm up and down? How quickly up and down? Is there anything controlling the sparks, ecu etc or is it points/ dizzy? I would suspect out of balance and an air leak, nothing more complicated. Quote Link to comment Share on other sites More sharing options...
dirty diamond Posted April 21, 2012 Author Share Posted April 21, 2012 hi markcoopers, its reving up and down about 5 to 800 revs probably about every 10 to 15 seconds, its a 1700 crossflow with electronic points/dizzy, i'll look for leaks tomorrow, thanks for your help, dd Quote Link to comment Share on other sites More sharing options...
markcoopers Posted April 22, 2012 Share Posted April 22, 2012 That sounds like air or electrics. Is there a vacuum advance? Tis might be something to look at as it sounds like it is experiencing a variable signal or set of conditions. I am not familiar with dellortos but webers are sensitive to the clamping and sealing to the manifold. Too tight or too loose will cause allow sorts of odd running. The smallest of air leaks will allow it to rev harder but this might change the seating of nthe carb and thus seal the leak and then drop the revs. Vacuum hoses being old and perished is another. They were fine until removed and then refitted, the disturbing of them often allows the smallest of holes to form and you will be for months trying to find it. My advice would be to change 1 tiny thing at a time, all around what was removed and refitted, it will not be a major catastrophic element? See the posts from the chap with a x flow a few weeks back where he continues toy changed so much that we could not help him identify any one specific issue. One other question, other than the erratic idle I assume it drives fine, revs and pulls under load as it used to? Quote Link to comment Share on other sites More sharing options...
dirty diamond Posted April 23, 2012 Author Share Posted April 23, 2012 hi again, put a new gasket on and it now starts running at 22000 revs for a minute or so then settles to about 17000 revs and when i switch off the engine petrol drips out of one of the carbs which makes my think (probably wrongly) that its getting to much petrol. I don't know if it drives/pulls well as i haven't had it on the road yet, but should be taking it for it's mot bank holiday weekend so i'll find out then, regards dd Quote Link to comment Share on other sites More sharing options...
SootySport Posted April 24, 2012 Share Posted April 24, 2012 hi again, put a new gasket on and it now starts running at 22000 revs for a minute or so then settles to about 17000 revs and when i switch off the engine petrol drips out of one of the carbs which makes my think (probably wrongly) that its getting to much petrol. I don't know if it drives/pulls well as i haven't had it on the road yet, but should be taking it for it's mot bank holiday weekend so i'll find out then, regards dd If petrol is coming out of the trumpets then the Needle valve is leaking or the tabs on the float assembly are letting to much petrol into the chamber. Found that on one of my Dellortos after a rebuild, I forgot to fit the aluminium washer. Quote Link to comment Share on other sites More sharing options...
SootySport Posted April 24, 2012 Share Posted April 24, 2012 Parts diagram for you http://www.google.co.uk/imgres?imgurl=http://www.gruntled.com/Dellorto/DHLA-DIAGRAM.gif&imgrefurl=http://www.gruntled.com/Dellorto/Diagram.html&h=671&w=650&sz=46&tbnid=iERWfPFuEeY_sM:&tbnh=228&tbnw=221&prev=/search%3Fq%3Ddellorto%2BDHLA%2Bparts%2Bdiagram%26tbm%3Disch%26tbo%3Du&zoom=1&q=dellorto+DHLA+parts+diagram&hl=en&usg=__EovbhmzKwXmVp2seuf7rP51HEv8=&sa=X&ei=4QOXT8PyNITF0QXUlOGYDg&ved=0CBQQ9QEwAA Quote Link to comment Share on other sites More sharing options...
CL290005 Posted April 24, 2012 Share Posted April 24, 2012 DD wish you would have asked couple of weeks ago threw my setup info away, I did download it from the internet if I remember correct you have to search on Alfa sites as the DHLA was standard fit on the Alfa. Its been years since I set up but I remember you turn the carb upside down and measure the float position 18mm seems to be in my mind but as I say its been years and mine were 45's but they are same format this might help http://www.aircoolednut.com/erkson/ttt/engine/carbs/dellorto.html Chris Quote Link to comment Share on other sites More sharing options...
dirty diamond Posted April 24, 2012 Author Share Posted April 24, 2012 thanks chris, I'll start searching the alfa sites, I should have thought of that as the former owner got them off an alfa, regards dd Quote Link to comment Share on other sites More sharing options...
dirty diamond Posted April 24, 2012 Author Share Posted April 24, 2012 hi soot1e, thanks for the info and the diagram link, regards dd Quote Link to comment Share on other sites More sharing options...
CL290005 Posted April 24, 2012 Share Posted April 24, 2012 http://www.aircooled...s/dellorto.html DD have a look at the link there is some good info Quote Link to comment Share on other sites More sharing options...
markcoopers Posted April 24, 2012 Share Posted April 24, 2012 Too much petrol will on it's own not cause it to rev at 2200-1700 rpm, it needs oxygen as well. I would suggest that a simple balance and set up, along with the linkage to check that it is all at the 0 position. If it is then there will be an idle adjust screw, adjust this down to set the correct idle..... Quote Link to comment Share on other sites More sharing options...
SootySport Posted April 24, 2012 Share Posted April 24, 2012 Too much petrol will on it's own not cause it to rev at 2200-1700 rpm, it needs oxygen as well. I would suggest that a simple balance and set up, along with the linkage to check that it is all at the 0 position. If it is then there will be an idle adjust screw, adjust this down to set the correct idle..... Very true but he does say it's leaky petrol when stopped so he has to cure that problem first. When that is done follow this for set up http://www.s262612653.websitehome.co.uk/DVAndrews/dellorto.htm Quote Link to comment Share on other sites More sharing options...
dirty diamond Posted April 24, 2012 Author Share Posted April 24, 2012 thanks guys, I'm taking it all onboard. can't wait to get back home and put all your advice to practice, regards dd. Quote Link to comment Share on other sites More sharing options...
SootySport Posted April 24, 2012 Share Posted April 24, 2012 If you bought the DHLA service kit like I did, the needle valve and brass holder, which come in the kit, are a matched pair, you need to fit the same value needle valve and holder together or they will let petrol into the chamber when the engine is switched off, this will eventually overflow into the trumpets as yours is doing. The other reason for the leak is the tabs on the float assembly. They should push the needle valve into the brass holder and shut of the flow of petrol when the float is at it's highest setting. A little bit off tweaking is required there. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.