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PostPosted: April 27, 2016, 3:53 pm 
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Joined: August 18, 2015, 12:41 pm
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Location: Seattle area (Woodinville)
After years of owning and occasionally reading the next to usless Haynes book, I did some web searching and found "WEBER Carburetors" by Pat Braden and "How t build and power tune WEBER and DELLORTO ...Carburetors" by Des Hamill.

Reading through them I can now understand how they can be so exasperating to set up.

You need to start with carb venturi, main and idle jets that are appropriate to your application installed to get carbs thta are at least functioning in the ballpark.

Idle sybchronation and idle speed adjustments need to be made at the idle adjustment on the carbs. After that you never touch those screws. All other low to medium speed adjustments are made by changing the idle jets. According to Braden, virtually all low to medium speed driveability issues, the ones we encounter in every day driving, are caused by incorrectly-sized idle jets.

My assessment of the books is that the Braden book is better for understanding how they work and for initial set up.The Hamill book is good for the actual build and maintenance information, and for seat of the pants tuning. Neither addresses using an oxygen ratio gauge.

If I were to get one, especially before purchasing carbs, I'd go with Braden. Especially if I were planning to use an oxygen ratio meter to tune them. If I were be taking them apart to rebuild, or doing test driving to tune them I'd add the Hamill book.

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PostPosted: April 28, 2016, 8:55 pm 
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Location: BC, Canada. eh?
I have all 3 books, and I'm STILL not looking forward to trying to tune these wee beasties! We used to have a dyno in town, which would have simplified matters considerably, but they closed up shop and there are no others, so all tuning will have to be "seat of the pants".

There are many issues to be considered - even the series of DCOE is crucial. When I bought mine, not many people were putting them on Zetec engines, and 45DCOE's, as long as they were a matched pair, were considered great.

Now, as it turns out, the older, 3 progression-hole carbs I have are entirely unsuited to the Zetec engine, and apparently will have a guaranteed, giant, off-idle stumble that can't be cured, even with a dyno & buckets of jets. There is a 5 progression-hole series that IS well suited to the motor, but drilling the extra holes (in the carb throat, just at the rest position of the butterflies) to create your own 5-hole carbs is supposedly something done only by serious Weber experts, lest you end up with $1500 worth of junk. On the other hand, I no longer have the wherewithal to replace the ones I have, so...

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PostPosted: April 29, 2016, 1:10 am 
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Location: Seattle area (Woodinville)
You can always use them as a really cool looking throttle bodies with an EFI setup. A lot of people are supposed to have done it.

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PostPosted: April 29, 2016, 5:04 am 
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Location: England
With Webers I only buy new and from a reputable, knowledgeable supplier and tuner. Given the correct info they will come in the ballpark straight out of the box. Taking a generic or secondhand weber can be a very costly and frustrating time consuming ballache when you add up the cost of chokes,jets and gaskets.

Bob

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PostPosted: June 18, 2016, 8:54 am 
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Location: central Arkansas
Back in the early '80s I acquired a Weber setup. Tuning information was almost nonexistent, and so were parts. Inglese never would answer letters or the phone, and CP Performance wouldn't ever give me any prices for jets and bits, much less condescend to take an order.

Something you have to remember is, just because you *can* tweak something, doesn't mean you *have* to. A friend of mine had built a beautiful tune for his EFI car, but every now and then he'd slide off into a parking lot and drag the laptop over to start dinking with something again; usually, some driveability issue that nobody else could discern.


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PostPosted: June 19, 2016, 12:36 am 
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one of my favorite Colin Chapman quotes:

Quote:
Make the suspension adjustable and they will adjust it wrong. Look what they can do to a Weber carburetor in just a few moments of stupidity with a screwdriver.


I'm scared of Weber's (dellorto's, mikuni's) myself. That is one reason I went EFI. I have a lot of respect for those who can tune a Weber properly.

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PostPosted: July 6, 2017, 4:16 pm 
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Reviving an old "necro-post", here.

Further to my earlier rant about progression holes on 45 DCOE Webers, I've continued to do research (for yet another year), and have learned a few things about the massive, overwhelming stumble that occurs on DOHC 16-valve engines with them.

Apparently, the breathing of the newer DOHC engines is sufficiently good at low RPM's that, without modification, current "Series 152" 45 DCOE's can't supply enough properly-metered fuel to keep them running properly. When the butterflies are first cracked open a tiny bit, the carb throat "progression holes" are gradually & consecutively uncovered by the edge of the throttle plates, allowing fuel into the airstream. These holes, (3, in current model 152 45 DCOE's) simply aren't up to the task, and the engine will run hugely lean.

Up until recently, the "cure" (a Band-Aid fix, at best) was to use enormous idle jets to flood enough fuel into the carbs to keep the engine alive.

Optionally, you could have your existing carbs drilled for extra progression holes...but, this requires the services of a master machinist, experienced in this modification, and equipped with a special jig (no longer available anywhere - I've checked!) & milling machine. As for trying to do it at home, well, good luck with that!

Unfortunately, these carbs run on the "idle circuit" all the way up to between 3,000 and 3,600 RPM (so, "idle circuit" is clearly a misnomer), which comprises the majority of driving outside a race track. Even with massively oversized idle jets, there's a stumble (and sometimes even frequent stalling), clouds of grey smoke from unburned fuel, and horrendous fuel economy overall (think heavy truck, big block, full throttle fuel economy), not to mention trying to ignite all that fuel. There has to be waaay too much fuel all the way through the circuit, just to ensure there's enough available during the moments that the engine needs it.

There are now, however, 152 Series 45 DCOE's with extra "progression holes" in the carb body throats to help combat this issue. You can buy 152 "G" model carbs now, which have 4 progression holes per choke, and these apparently will solve the issue, for most engines anyway.

The Zetec (the engine I chose, of course!) is, it seems, spectacularly susceptible to this problem, and the "G" model 152's only go partway toward solving it. To that end, a company called Webcon in England (which pioneered the fitting of Webers to Zetec engines) came out with special, 5-progression-hole carbs, specifically for the Zetec. Purportedly, these carbs will actually CURE the problem in Weber-carburated Zetec engine, once and for all.

As there's likely no way I'll ever get my 3-progression-hole 152's to run properly on my Zetec (if I could, I'd be the first one, in 20+ years of trying & failing by experts), I'm negotiating with a company in England to purchase a set of the 5-hole Webcon carbs at a price that doesn't look like my mortgage payment.

We'll see - as I anticipate plenty of other variables to deal with in getting my engine to run, I'd really like to eliminate as many as I can. Having carbs that should work, right out of the box, would help a lot, I suspect.

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/


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PostPosted: July 6, 2017, 4:23 pm 
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Joined: December 29, 2007, 10:41 pm
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Location: Vancouver, BC
Zetec,
Are you a follower of : https://groups.yahoo.com/neo/groups/sidedraft_central/info

I think Keith who runs the board made up a drill jig for progression holes, though I may be wrong. In any case, it's a great place to ask question and learn about DCOE's


Rod


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PostPosted: July 6, 2017, 4:27 pm 
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Location: BC, Canada. eh?
No, I wasn't even aware of the group! I'm a bit of a Luddite, though - I've tried to join other Yahoo groups in the past, and failed miserably. I will try it again - the ability to have the brief use of a progression hole drilling jig would be WONDERFUL...and save me a bucket load of $$$

**Edit - Hmmm...it insists I create a Yahoo email account etc. before I can even look at postings, search, etc., and as recently as last Saturday I heard experts advise that Yahoo is to be avoided due to email insecurity issues. Makes me nervous...my wife was recently the victim of ransomware sent via an email...lost everything...

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/


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PostPosted: July 6, 2017, 6:54 pm 
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You may also want to look at this link, if you haven't found it yet, it pertains to Alfas, but the same issue. http://www.alfabb.com/bb/forums/carburetors-fuel-injection-air-intake/32856-weber-dcoe45-152-45dcoe-progression-circuit-modification.html There appears to be two ways to solve the problem. The first page has the primary details, and 31 pages follow.


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PostPosted: July 6, 2017, 7:08 pm 
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Zetec,
I'll pose the question to Keith and get back to you with an answer.

Rod


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PostPosted: July 6, 2017, 7:15 pm 
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Location: Seattle area
I'm with Chuck. A decent EFI w/ITBs and a MegaSquirt will beat the carbs not only in performance but in ' get it running time.' A lot of folk are hesitant thinking the learning curve is too steep but I thought it was practically a flat line compared to carbs and I had access to a free set of Del Ortos.

However my engine came with ITB's/ I didn't trust myself to figure the stock ECU and harness and went MS2. A little fiddling with Tuner Studio, and I might add some sage advice from those in the know, I have a decent, worry free running 20V 4AGE.


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PostPosted: September 21, 2017, 7:03 pm 
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Well, I finally found a fix for my Weber issue. Voila! A brand new set of custom-made 5-progression hole Weber 45 DCOE's, fresh from Webcon & Advanced Automotive in the UK. With all the variables in my build (parts from all over, and no "donor" car), including an untested, bespoke ignition system, I decided that removing the carburetion variable from the mix just made sense. It's expensive, but should eliminate all the common vices of Zetec engines on Webers.

Purty...ain't they?!

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http://zetec7.webs.com/


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PostPosted: September 21, 2017, 8:24 pm 
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Location: No. Nevada
NOTHING beats Webers for looks, and performance is on par with or better than EFI.

So how much for that pair of "Junk" 3-hole 45's you are not using, and are they a matched set?
Might just work on a small V8, or even better with two more!

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PostPosted: September 21, 2017, 8:27 pm 
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Yes - the old ones are a matched set. They supposedly came directly off a Zetec-engined Formula Ford. Not sure what I'm going to do with 'em now. Maybe there's somebody on the forum that needs a pair. Supposedly they'll work with almost any engine out there....except a Zetec :BH:

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/


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