givemethebighammer
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| posted on 7/3/05 at 08:34 PM |
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Drilling more progression holes
After a few weeks of running the car on the twin 45DCOE152 carbs I now accept that the progression phase (2500-3200 ish rpm) is crap (the car pops and
spits badly on light throttle and is a real pain to drive round town at low speed). Everywhere else in the rev range the car performs very well.
Talking to various engine tuners this is because my carbs only have 3 progression drillings. Modern 16v engines require four to five holes on account
they flow more air than older engines.
As much as I understand drilling more holes is not to be taken lightly. They need to be of the right size and in the right location to be of any use.
Get it wrong and you could make things worse. I called Webcon who said that when they were still selling the 45 DCOE they would put carbs that
required modification on to the back of a production run of carbs destined for zetec engines (i.e. 5 progression holes before they were sent to the
customer). However they are no longer selling the DCOE 45 so don't have the jig set up to drill them. They said they will get back to me on
this, but I am not too hopeful (I may be wrong). The question is can anyone else make this modification for me with the precision and accuracy
required ?
thanks
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dblissett
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| posted on 7/3/05 at 08:47 PM |
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progession holes
i dont think the accuracy/precision would be a problem for a local tool maker
the problem is finding out what size the holes need to be and where to put them
may be webcon can tell you
good luck dave
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ady8077
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| posted on 7/3/05 at 08:49 PM |
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Hi
Do you get practical performance car?
Feb's edition had a good artical on setting up dcoe's, I could email a scan if you like?
As for progression, have you checked that the butterflies are just covering the first hole whith the throttle closed? If not you may need different
idle jets
Adrian
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britishtrident
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| posted on 7/3/05 at 08:55 PM |
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Sounds more likely the air corrector jets are too big. 2500 to 3200 is the transition from idle to main jet which is leaned out by the air corrector
to prevent over richness.
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givemethebighammer
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| posted on 7/3/05 at 09:11 PM |
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I do get PPC, however I missed the first article on tuning DCOE's so if you could scan it for me I'd be grateful. The carbs are set up
quite well but having talked to a couple of rolling road people (Northampton Motorsport and John Noble) They both say that with only 3 progression
holes no amount of tuning is going to remove the issue I have. Weber have researched the issue and the recommended solution is to drill more holes. I
just need to know where / what sizes and who will drill them for me.
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britishtrident
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| posted on 7/3/05 at 09:19 PM |
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Progression holes work when the throttle is just comming off the throttle stop say 1100 to 1500 rpm.
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NS Dev
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| posted on 7/3/05 at 09:44 PM |
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quote:
Originally posted by givemethebighammer
I do get PPC, however I missed the first article on tuning DCOE's so if you could scan it for me I'd be grateful. The carbs are set up
quite well but having talked to a couple of rolling road people (Northampton Motorsport and John Noble) They both say that with only 3 progression
holes no amount of tuning is going to remove the issue I have. Weber have researched the issue and the recommended solution is to drill more holes. I
just need to know where / what sizes and who will drill them for me.
Looks like you have had some joy on the westy forum on this one!
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ady8077
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| posted on 7/3/05 at 10:20 PM |
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Hi
I've scaned it, 4 pages about 400k each ( a bit big but the pictures look good )
u2u me your email addy and i'll send them
Adrian
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givemethebighammer
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| posted on 7/3/05 at 11:05 PM |
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ady8077 you have U2U
yup I use the Westfield forum as well. Different attitude (a bit more serious sometimes) on their but still very useful none the less.
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NS Dev
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| posted on 8/3/05 at 08:17 AM |
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Yes, I use it as well (obviously!) and it's useful too! The lotus 7 (Caterham) forum is handy now and again too!
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