You'll need to get a matched DCNF because the order and size of progression holes varies across the various 40 DCNFs available. A very common mistake with quad webers is to simply replace one or two with non-matching and then find that the carbs can't be synchronized properly ("I just had Giuseppe rebuild two of them and install two new ones and the car runs like crap"). Perhaps others here have had a different experience but that's been my experience and opinion at least.
If reliability and ease of maintenance is your goal ( i guess it's power in your case, but anyway) you might considder Bosch CIS... i'm not sure it will fit bolt on completely( are the manifolds flanges to the head the same? anybody know?) But if this is the case than, some pro's CIS will come relatively cheap CIS is very easy to use, no fiddling whatsoever when set. CIS probably can operate with your current ignition CIS will improve your miles to the gallon considderable some contra's CIS will need new camschafts CIS will cost you power CIS will need some rewiring (altough you would be surprised how simple it actually is when you take a closer look) CIS will require some upstream changes (pump etc, and minor tankmodification the loss of power will be there but the gain in easy handling just could weight more replacing just one carb will not solve your problems..
Hello Stratos, no, I don't work for Michelotto! I just live 50 Km. from Padova, that's all! That's what I meant with "come here". I think I'm lucky, because when I'll get my Ferrari I'll be very close to very capable hands Ciao
Yes, CIS will bolt right on a GT4 engine, the wiring is very simple, plumbing is easy. And all of the positives you mention are true: Plus no fuel smell in the garage when you shut it down. But you left off some negatives: resale price will take a big hit because carbs are preferred on the marketplace and the engine intake sound is a bit muted. ITB/EFI will make resale worse, probably, but intake sound will probably be better or the same depending on execution. I think fuel mileage with CIS is way better, but I need to replace my speedo sender and get some MPG numbers. But in an totally unscientific data point I have a friend with a later GT4 and on a 3+ hour drive he stopped for fuel at just under a quarter tank and I still had nearly half a tank showing. Our cars are matched for acceleration. Perhaps I am making up for the resale hit every time I fill up? I guess I need to drive it more to make it more profitable? As far as I know I have the only CIS GT4. I have not seen another conversion, however I have seen complete engine swaps with a CIS QV into a GT4.
Just another view: Your carb prob's sound really frustrating. I've seen 308's where the Webbers dialed in perfectly, and I've seen them behave not-so-perfect. From the standpoint of failure modes and probability (and also cost), one carb having a serious problem has some chance, two carbs is significantly less - - - - and so on. Can you tell maybe by looking at plugs or a portable exhaust gas analyzer which carb(s) are causing trouble? Too rich, way lean etc? IMHO, Webbers can do a great job and just are so in character with the Dino GT4 that I'd probably start replacing carbs before going FI. This may be redundant info for you: A friend who's very talented with multi Webber setups has seen many carbs with internal passages plugged from corrrosion (that white mineral like deposits that grows in carbs). This is more common as cars age and sit. He's drilled out the lead plugs, cleaned the passages and re-install new plugs. Also, I had a Webber that wasn't responding and it was driving me pretty crazy. He sprayed around the carbs with carb cleaner while running and found a missing lead plug that seals one of the passages. I pulled off that one carb, and he showed me his technique for putting a new lead plug, and about 45 minutes later, the carb was back on, responding, and able to be synchronized. Having said all that, whatever path you take, I hope you solve your problem so you can enjoy your car.
Steven, no, I haven't completely lost my mind. No way I am going to put a rag in the mouth of my little Dino by installing CIS! I know exactly which carb (and which barrel in fact) is my problem: the #3 cylinder. Someone at some point in time has apparently got the idle mixture screw all the way out and then put it back in at an angle. Obviously when it didn't turn in quite nicely, he'd got out The Big Screwdriver, and thus our intrepid hero has ruined the threads on the idle mixture screw on the weber barrel of my #3 cylinder. Nice! The guy who has been working on the carbs recently found the problem and partially solved it by doing some drilling and refitting. Problem is that this cylinder is now running much leaner than the others. Appartently not wanting to spend a whole lot of time on it, he elected to put some bigger idle jets in all 8 cylinders (56's) and send me off on my trip to Italy. With the prospect of 2000 miles of driving and 8000 feet high mountain passes, running 12 mpg and a stinking idle mixture didn't seem like the best of ideas to me. And so I put in a set of 50 idle jets. The car ran much better, except for the fact that it was clearly running on 7 cylinders. Putting the 56 back into my #3 and the 50's in the rest restulted in a pretty decent running engine, but obviously not what I'd want to run for the rest of the cars life. While writing this, it's obvious to me that my initial question regarding EFI is merely my attempt to avoid the real topic: how to fix a Weber. I guess what I could do is drill the offending hole out completely, turn an aluminium plug on my lathe and fill the hole with this. Then start anew with the idle mixture screw hole in an attempt to duplicate the other 7. Of course, then there would be the issue of the progression holes, which really seem to be too small on all 8 barrels. 1974 GT4 specs call for 5 progression holes, the first being the biggest at .8mm. Mine has 4 holes, the fist being only .4 or so mm. And indeed, my mixture shows a dip at just above idle. Drilling out the first progression holes to something closer to that .8 mm could in theory richen the mixture at just above idle enough for me to fit smaller idle jets and thus get the mixture closer to the 13:1 or so one would like to run down there (rather than my current 11:1). Having experience with the ease of programming EFI setups prompted me to ask the initial question.... But I'm rambling. I'll have a good look at how I could fix that idle mixture screw first and will take it from there... Hans
Yes I do Chris. But there's a bunch more things I'd want! Can't have em all.... Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
It's nice to see someone with their priorities in order. I just cannot understand why anyone would spend so much money on a car when there are such amazing aircraft available...
