Weber 40 DCOEs

[4129R]

Converting my Federal cars to UK spec, I am changing the cylinder heads from Zenith to Weber heads.

So I had to buy several pairs of matched pairs of 40DCOEs on eBay to fit those heads.

After cleaning them up, and changing the chokes and jets for roughly the right settings, I have the task of getting the T banjos, and the dual linkages, so the carbs work properly together in pairs.

Getting the cable linkage was fairly easy. You have to get one that attaches to the top of the carb, not the underside, as that will foul the casting which links the 4 inlet tubes on Weber heads.

Getting the male and female links which connect the two carbs together so the 2 x butterfly bars open together has been a bitch.

I have been getting parts from Webcon. http://www.webcon.co.uk/ Originally the female parts were correct, but the male link tab missed the female screw part by 1/2". Then the new male part had the male tab 90' out of sync. So I went to Webcon to see Martin there to sort it out. They are very close to Heathrow Airport.

Martin is a wealth of info on Weber. I took the carbs with me, he identified them as coming from a Holbay Hunter. These DCOEs are different, as they draw air in from the top during idle, and not through the side 1/2" hole in the main body of the carb.

He told me Webers were made especially for individual cars, and those for a Lotus Cortina differed from a Lotus Elan, even though the engine was the same, because of the weight of the car required different characteristics.

He also told me there are three holes drilled near each butterfly on some carbs, and luckily it seems by Holbay Hunter carbs had those three minute holes drilled, which are needed for Lotus engines.

Webcon are Weber specialists and supply all over the World, so it seems I got lucky going to the top of the supply chain.

I thought a 40DCOE was it, but apparently not, there are many different types, so not only do the chokes and jets have to be compatible, but the carb bodies have to be suitable as well.

I have 5 more sets to sort out now, so I will be visiting Martin with a large shopping list soon.

So the moral of this story is to go to someone who knows all the intricacies of these specialist parts, as it is a minefield out there if you get it wrong.

[surfguitar58]

So, are webber cylinder heads just a bloody nuisance in the UK and on the continent, getting in the way, so plentiful people are tripping over them, using them for door stops?  Or are you buying aftermarket heads like Burton or QED?

I saw one (albeit complete) used webber head going for $6950.00, and another place advertising used Stromberg heads "Starting at $350".

t

[jbcollier]

Yup, there are no "generic" Weber side drafts out there.  They were designed and built to suit a specific application.  The drillings near the butterflies are the "progression" or "transition" circuit.  As the butterfly opens, it exposes these holes to engine vacuum allowing mix to enter to take up the slack until the main circuit kicks in.  While more, or larger, holes allow more mix as the throttle opens, it's a balance because the holes lean the mix when the throttle is closed or just opening until they are all fully exposed.

[4129R]

Second hand Weber heads are rare, plus you have to get the groove machined in where the cam alternator pulley wheel is sited. There are not many machine shops who can do that.

one of the sets of 40 DCOEs I bought has a cracked mounting flange, and is very badly corroded so none of the screws come undone, the trumpets are stuck in the chokes, so not much use even as spares.

I will take the heads to get checked for flatness and porosity before getting the ports polished, and the grooves cut.

Not only is the power up, but they look and sound great.