Quote:
BBD bolt pattern adapter to Weber pattern. I wonder if you couldn't make your own adapters for less money than purchasing those.
Ah, I forgot that was a 2-piece adapter! 
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| Dual Weber DCD carb dilema https://www.slantsix.org/forum/viewtopic.php?t=58994 |
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| Author: | Pierre [ Mon Jan 18, 2016 5:35 pm ] |
| Post subject: | Dual Weber DCD carb dilema |
Does anyone remember thesedual webers? I was the one that ended up with them. I had some difficulty getting a offy 2x1 manifold at a decent price, but I finally got my hands on one and started mocking things up. A major hurdle - I've come to find out there are two patterns weber carbs used, kinda like the small and big holley pattern. These webers use the bigger pattern. The width (Short) dimension of the weber flange just fits on the respective dimension of the manifold. The length (long) dimension of the weber flange is actually bigger, by say 1/8" or more. If you align one side, the bolt holes are actually exposed on the other. If I center the long dimension and have a little overhang of the carb on each side, the bolt holes just barely fit inside the flange, but they will be in the far corners, pretty much touching the walls. I *MAY* be able to drill/tap a 1/4" hole, but I suspect it will be very weak as the threads will be super close to the flange wall. And it's aluminum already... so I really don't want to chance it. The other thing - The primary (or secondary if you flip it around) barrel will be very close to the 2 or 5 runner. I suspect fuel distribution will be poor, and one major selling point of dual carbs on the slant is to have better distribution.... Third, but probably not last... the linkage won't be as easy as originally thought. These carbs have the throttle shafts parallel to the crank. This will require a bellcrank/rod type setup which will be plenty more complicated then a simple cable. Ok, I can get around the linkage issue. It will be a pain but doable. I may be able to add some material to the floor of runners 2/5 in the plenum to artificially lengthen it but it still won't be right. The major hurdle will be mounting.... I can add (weld) material to the flange, mill things flush, then drill/tap but that's going to be a HUGE PITA and will likely make a mess of the manifold. And there won't be any going back. I've pretty much given up on these. Misery loves company... what would you guys do? Oh, salt to the wounds - I've already bought air cleaners, gaskets, linkage for these guys too. |
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| Author: | rich006 [ Tue Jan 19, 2016 5:31 am ] |
| Post subject: | |
I'm no expert on carbs, or anything car-related for that matter, but...you're choosing between a PITA project of dubious benefit (based on my reading of your description), and cutting your losses--admitting that you made a costly mistake. Which choice would you be more likely to regret? After doing all the work you describe, would you have a great sense of pride and accomplishment or would you merely be relieved to be done? Will you like your car more with the new carb setup, or will you resent the effort of installing them? |
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| Author: | coconuteater64 [ Tue Jan 19, 2016 6:59 am ] |
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We've all heard buyer's remorse. True wisdom is recognizing the mistake and going with Plan B. I learned the hard way: I have a long history of failed projects to remind me that I can spend money and time going the wrong way. Like the Porsche powered VW bus I never finished (couldn't suss out the fuel injection and after spending a princely sum, sold it at a huge loss to a guy who had it running in a week.) Like Kenny Rogers said, "You gotta know when to hold em, know when to fold em..." |
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| Author: | Reed [ Tue Jan 19, 2016 8:12 am ] |
| Post subject: | |
Mount the carbs perpendicular to the crank. Drill out the carb holes in the intake to match the two barrel carb throat. Machine adapters to mount the wide two barrel bolt pattern on the intake (or buy premade carb adapters). Rig up a throttle system that has a single cable pulling a lever in between the two carbs that will open the throttles at the same time. Run a cable style kickdown from the center throttle point. Easiest way I can think of mounting the carbs for best fuel distribution and simplicity. |
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| Author: | sandy in BC [ Tue Jan 19, 2016 8:24 am ] |
| Post subject: | |
Its not fun to be in deep with a situation that looks to be harder than originally planned. I played Webers on a Chev 6 long ago.....and ended up making plates (aluminum) that the carbs bolted to.....and adapted the plates to the manifold. I was using 3 carbs (webers for Cortina GTs ) .....and the linkage was really difficult. The nice part about the adapter plates was I did not have to overly mod the manifold....and once I had a pattern the other 2 plates were easy. The 1/4" plates secure to the manifold with countersunk Allen screws. The carbs bolt to the plates. .......sounds easier to go EFI. |
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| Author: | Reed [ Tue Jan 19, 2016 8:49 am ] |
| Post subject: | |
Quote: .......sounds easier to go EFI.
+1, but that won't really help Pierre....
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| Author: | Joshie225 [ Tue Jan 19, 2016 9:23 am ] |
| Post subject: | |
I'm sorry for your pain. I also vote for an adapter plate. I found a page stating that the Weber DCD has the same mounting pattern as the DGV type. This means there are already adapters from this pattern to the Carter BBD aka "small 2bbl" mounting pattern. I would see if the very common small 2 bbl pattern will fit on the Offy manifold and if so get the off the shelf adapters. This way you don't have a strange one-off bolt pattern on the manifold and if someone ever wants to try dual BBDs or some such it's no problem. |
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| Author: | Reed [ Tue Jan 19, 2016 9:35 am ] |
| Post subject: | |
BBD bolt pattern adapter to Weber pattern. I wonder if you couldn't make your own adapters for less money than purchasing those. |
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| Author: | ProCycle [ Tue Jan 19, 2016 9:46 am ] |
| Post subject: | |
I just made a similar adapter using some phenolic block. It doubles as an insulator. |
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| Author: | Joshie225 [ Tue Jan 19, 2016 11:11 am ] |
| Post subject: | |
Quote: BBD bolt pattern adapter to Weber pattern. I wonder if you couldn't make your own adapters for less money than purchasing those.
Ah, I forgot that was a 2-piece adapter!
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| Author: | coconuteater64 [ Tue Jan 19, 2016 5:54 pm ] |
| Post subject: | |
I hate that Pierre had such a disappointment, but if he can get it to work, it could be a really good thing. |
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| Author: | SlantSixDan [ Tue Jan 19, 2016 6:27 pm ] |
| Post subject: | |
It's not a happy thing that Pierre is feeling daunted. I understand how he feels; putting together a twin-carb changeover—any twin-carb changeover—involves fiddling, fettling, fabrication, and, yes, frustration. This particular changeover has been done successfully, and if Pierre chooses to press ahead, I have no doubt he will make a fine job of it. If he changes his mind and decides to go a different direction with his induction setup, I'm sure someone else will pounce on the parts and make their own go of it. |
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| Author: | Pierre [ Tue Jan 19, 2016 7:19 pm ] |
| Post subject: | |
Dan - Dual large pattern DCD's on the offy 2x1 has been done before? Link / pix plz, I'd love to see it. I've seen the Pierce setup and similar that uses the dual synchronous webers (the smaller flange pattern I was talking about) before but not the progressive DCD's. Don't get me wrong I'm not necessarily whining about the challenge I'm more shocked / surprised that it occurred. People will pounce? Really? If you know of a buyer that will give me what I paid for them (manifold, carbs, extras) I'd be inclined to take it. Your post was up a month before I bought them. An adapter is a better option then welding on the manifold. Height becomes an issue though. I'll have to study that and compare to the stock carbs. They appeared to be taller at first glance. Reed, I'm not following your arrangement suggestion. Sketch it out? Let's wave a magic wand and say they have been mounted and linkage taken care of. What's the consensus on the fuel distribution issue with the barrel being closer to the 2/5 runner? To give an idea - with the weber gasket centered on the flange, the inner cutout stretches from the outside of the 1bbl mounting stud hole to the outside of the other stud hole. |
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| Author: | kesteb [ Tue Jan 19, 2016 10:45 pm ] |
| Post subject: | |
No difference then the fuel distribution for a 1v, 2v or 4v and the 3 & 4 manifold runners. Make an adapter plate and do google for linkage suggestion. Dual webers have been used on numerous inline engines. You may need to make linkage but Summit should have all the parts needed. |
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| Author: | Pierre [ Wed Jan 20, 2016 7:00 am ] |
| Post subject: | |
Large weber on offy2x1 is closer to 2/5 then single carb is to 3/4 |
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