See below:
----- Original Message -----
> .... The car still ran. So from there, I looked carefully
at the two carbs, and noticed that the throttle shafts weren't at the
same "level", the back one seems to be hung up slightly open.
> When I covered
the front, the car died within a couple seconds. When I covered the
rear, nothing happened. Not even a change in idle speed.
These seem to conflict. If the rear is open that will be the one still
running the engine, so covering the front should do nothing. If covering
the front stopped the engine that is the one still open. If covering the
rear did nothing that is fully closed.
> So next step, sprayed carb cleaners at the throttle shaft; I was able
to get it to slow down *once*, but only when I sprayed the *front* carb.
Carb cleaner, as opposed to oil, should make the engine run *faster*, as it
is an aromatic and combustible, and is easily sucked through very small
gaps. Oil should block any small gaps and hence cause the engine to run
slower, if the problem were vacuum leaks through the bushes from outside.
However if the leak is on the internal side of the throat and mixture is
getting past the butterfly that way, putting oil or carb cleaner on the
outside of the spindles may not make any difference. Again, if spraying on
the front carb altered the idle then it implies it is the front carb that is
running the engine, and has the problem, not the rear.
> At this point, I removed the carbs and looked at them. The
butterflies appear to fully close, I held a bright maglight to the
back and looked through them. However, it appears there is a gap
under the butterfly, perhaps this is where the HIF enrichment circuit
lives?
If you could see the same light on both carbs then that is unlikely to be
the problem, you are looking for a difference *between* the carbs. The
cold-start enrichment outlet is immediately on the butterfly side of the
bridge. The port under the butterfly is the outlet of the bypass port,
which begins immediately on the butterfly side of the jet. This should be
closed off with the butterfly fully closed.
>At this point, I am so frustrated I'm considering sending largish
quantities of B# to Burlen for a set of HS4 (I can let VISA deal with
the exchange).
You could try holding the carbs with inlet manifold side at the bottom and
the air cleaner side at the top, and pouring light oil (or petrol or
paraffin if oil doesn't run through) into the air cleaner end, timing how
fast it runs through each carb. If one runs through significantly faster
than the other that will be the faulty one.
PaulH.
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