Triple Weber DCOE connections?

[m5bb]

Anyone running triple Weber DCOE carbs connecting them across the butterfly shafts instead of the bar linkage with all the rods?
They make a arm that connects to the shaft and then meshes with another arm on the opposing carb.
This would eliminate all the linkage rods and all the flex and adjustment it takes to have this work.

I was told not to do this with three carbs? I know the 2002 guys do it with just two carbs.

Gary

 

[Stevehose]

That would be me :grin:

You'll be trading flex for flex of another kind.

The issue I have seen is that there appears to be some torquing of the shafts and/or coupler linkages by the time the last barrel opens. I see it when I hook up my Carbate on barrel #2 where the accel pedal linkage attaches and other barrels of the 2nd and 3rd carb. Most evident when accelerating quickly like during an up shift where the rear carbs have to "catch up" to the front one. It's subtle, but it causes some lean popping issues I think because you have to open the rear carbs more to keep it all synched. No issue at easy cruising. I also migh try hooking the accel pedal rod to barrel #1 of the 2nd carb instead of barrel #2 of the 1st carb and reversing the coupling to the first carb to see if it reduces some flex.

I am actually experimenting with going back to the crossbar and linkage rods but only using 2 rods (1st carb, second barrel and 2nd carb, 2nd barrel) then the intercouple between 2nd and 3rd carb. I have seen this setup on vintage photographs of my particular intake manifold (it's a clearance issue). But it's hard to find the right levers for it to work.

So yes it can be done, what don't you like about your current setup?

 

[m5bb]

Hey Steve,

We'll a couple reasons I thought the other connection setup would be better is there are less adjustments, it is simpler therefore less problems and the way it looks.
All those rods and arms clutter up the view of those beautiful 45 side draft Webers.
My throttle rod is currently of the left side of the second carb.
So the third carb would be the one at the end of the line so to speak.

Can't some of the play be adjusted out?
One suggestion was two throttle rods from the bell crank on the block but that may be difficult.

 

[JFENG]

Linkage

The let time I had a bmw other triple DCOEs was 30 years ago. I recall those stupid miniature turnbuckles had so much slop in the threads that tightening down the lock nuts would change the sync. That's why I went w the "ti" setup on my 2002's with a single actuator rod and the carb throttle spindles linked together. That setup was trivial to sync up and stay sync'd for years. Are there modern linkage bits without that lash that are easier wrt fine adjustments?

John

 

[Tierfreund]

I´ve seen setups where the linkage was mounted underneath the carbs pointing up. Looked very clean and avoided the tourqueing issue of "daisy chaining" the carbs..

 

[kasbatts]

The biggest problem I found when I was playing with DCOE's on my cars in the past is that the off the shelf throttle linkages are rubbish. They are usually bent bits of thin steel, brass bushes at best for the pivots and really cheap rod ends that are too small for the job, I have even seen some with clip on plastic rod ends the like that are found on RC cars!
If you have the ways and means of making something really nice from billet aluminium, with ball race bearings in the pivots and really good quality rod ends (of a decent size) for the links you will improve the feel and operation of the carbs no end.

Good luck

 

[m5bb]

The biggest problem I found when I was playing with DCOE's on my cars in the past is that the off the shelf throttle linkages are rubbish. They are usually bent bits of thin steel, brass bushes at best for the pivots and really cheap rod ends that are too small for the job, I have even seen some with clip on plastic rod ends the like that are found on RC cars!
If you have the ways and means of making something really nice from billet aluminium, with ball race bearings in the pivots and really good quality rod ends (of a decent size) for the links you will improve the feel and operation of the carbs no end.

Good luck

You got the rubbish part right but I am not a machinist nor do I want to make a 1 month project out of this. I like to drive my car. Sourcing good hardware is getting harder and harder.

I'm trying to simplify.

 

[Nicad]

I can post some close ups of the Alpina setup in about a week if that is of use.

 

[m5bb]

I can post some close ups of the Alpina setup in about a week if that is of use.

That would be interesting.
How is the Alpina different?

Of course will wait for photo.
Thanks,
Gary

 

[shanon]

Not sure if you guys have called Peirce Manifold about 'their' linkage set-up. Its far more stout than the Redline rubish. The Pierce kit has billet arms, etc...

Worked great for us.

HTH
-s

 

[jamesw]

Tempting. I didn't see anything about it on their BMW page though.

Cheers
James

 

[shanon]

link

http://www.piercemanifolds.com/product_p/pm3701-l.htm