Frank Krajewski <frankk@intap.net> wrote:
> I picked up a 1971 MGB recently on which the PO had installed a side
> draft Weber 42DCOE8, Number 4E. He couldn't get it to run smoothly and
> neither can I! Seems he, nor I, can find a place to connect the vacuum
> advance line on the manifold or carb. The vacuum line from the
> distributor is there but disconnected. Does anyone have any insights?
> Also cannot determine how to connect the choke cable. The PO has it
> connected but it is not connected properly and the choke engages but
> will not disengage unless I pop the hood/bonnet and restore it to its
> original position by hand! I suspect this is not the proper Weber for
> this car and may not even have a vacuum advance connection.
> Frank "Swamp Yankee" Krajewski
> http://www.bmcne.com
DCOE Webers do not have vacuum advance hookups.
You can fiddle with the springs in the dizzy mechanical advance to make up for
the missing vac. or buy a pure mechanical advance dizzy.
Can't help you with the choke question without a little more info -- it could
be a weak spring that won't close the choke, it may be that the wrong choke
assembly (there are right-hand and left-hand versions), it may be that the
cables are just hooked up oddly.
I run a 45 DCOE9 on a '70 B. It is too much carb for a stock engine, but
there's no reason it can't be made to run well. Check all the calibrated
parts inside (oops, buy a book first) and you'll probably find your problem,
if it is in fact a carb problem.
Off the top of my head, I'd say that the most important part to get the right
size is the chokes. If the motor is stock, 32 or even 30mm will be good for a
low-revving 'B motor. After that, emulsion tubes+fuel jets+air corrector jets
determine the mixture throughout the rev range; careful tuning here can make
this carb very smooth and not as inefficient as some would say.
Idle jets set idle mixture, and the pump jets (the fun part, the reason to put
a weber on it in the first place (well, that and the sound)) dump gasoline in
on acceleration.
If properly set up, they never wear out and never need adjusting, run
beautifully and give a little extra thump on acceleration. They are, though,
a pain to set up in the first place -- not unlike SUs.
Best wishes, and someone please jump in and correct the horrible errors I'm
sure I've made here -- like I said, this is all off the cuff.
M.
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