teddykan wrote:
I discovered that the AED (?), or the start-up
carb (it has the little pin that sticks out), was misbehaving.I would have thought that once warmed up this extra carb would be
deactivated. Alas it wasn�t. Even when warm it was on and made the
engine idle at 2500rpm and run rich (loads of grey smoke). When I
disconnected the lead to this extra carb the idle resumed normal
(although it hunted at 500-700rpm). When I reconnect the lead it
would stay low, but as soon as I blip the throttle the engine would
rev up and stay high at 2500rpm. What is going on and how do I fix
this? (I thought about making a manual switch to intervene)
The ‘pin’ sticking up implies that it is an aux starting carb, Richard…
In which case it is thermostatically controlled and in your case the
device arguably works as intended - it’s the thermostat switch that has
failed. In which case the device doesn’t ‘know’ that the engine is hot…
If this is the aux starting carb it works by opening an air passage and
an ajustable jet, the ‘rod’ thing, functions just like the jet on a
carb. As air is allowed in it passes the jet and drags in fuel and the
extra air increases idle - and all is shut off by the air passage
closing as power is cut by the thermoswitch…
That it cuts out when disconnected is as it should be - that it doesn’t
immediately raise idle when reconnected is a flaw, if the fault is as
suspected. But that is probaly something binding - it’s a primitive
device, and quite reliable. Adjusting it is part of the carb ajustments
- leave it disconnected while you are working on more importsant
things…
There continued to be loads of grey smoke pouring out of the engine
breather I suspect the no 4 piston rings were not freed up, or are
broken beyond repair. I�ve resigned to having to take the head off
and have ordered a head gasket (a gasket set costs some �74 but
just the head gasket some �40!). Also got the sump gasket and seals
as I may have to pop the no.4 piston out to get at the rings, or
whatever. Not even sure what size pistons they are (standard,
+0.020in or +0.030in?). Will have to see.
That’s the spirit, Richard - but I would still run a compression test
and note down the results, wet and dry. Even if it is just informative
you may need it to clarify some point when the head is off - you may
regret not having done it…
And honestly; doing a descaling operation with tough chemicals without
reading the fine print is rather rash. These are not exactly candy - and
doesn’t restrict their effects to the scale only…
Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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