> Hi Richard,
>
> We have an XS with a 912S and the Skydrive carb heat (hot water). We
> have had the engine run rough both on the ground and in the air, both
> cured within less than a minute after carb heat is turned on (usually
> after 10-15 seconds). We don't leave the carb heat on all the time
> because it raises the hot start temperatures, although it doesn't hurt
> performance when on (we have carefully checked this). In the air we
> have had carb ice at normal cruise and when throttling back. The carb
> temp gauge (supplied with the carb heat kit) indicates a few degrees
> from 0 deg C whenever we have seen this carb ice condition.
>
> We have also had the engine run rough due to what we believe is vapor
> lock. This has only happened in the winter time (when there are more
> volatiles in the auto gas), after a hot start, and typically after
> taking off from a higher altitude field. We have since added more
> insulation in the carb and fuel line areas, protecting them from the
> exhaust 'hot spots'.
>
> regards,
> Terry Seaver
> A135 / N135TD
Thanks for this, How does the carb temp gauge work, is it in contact with
the carb body or does it fit inside somehow. I have (currently) my external
temp probe blue-tacked to the side of one of the carbs with the metal
touching (I hope) the carb body. I will look at the temp very carefully from
now on.
I am more sceptical about vapour lock. You get it in winter but not in the
summer ? I know that there are more volatiles in winter fuel but In summer
there is much more heat around (esp in the land of the free !) Do you have
the return fuel line back to the fuel tank ?
I have another question :
In the cold today it did NOT want to start. I have noticed that during the
summer it started on the button. Now it takes several (in the case of today
12 minutes or so - not continuous !) churns on the starter. If it doesn't
start the prop tends to "bounce" almost hitting a (?) compression stroke and
reversing its direction (maybe 50 degrees)
Might this be lack of battery zoom so that the battery cannot overcome the
compression, or is it a sign that a mag is firing early ?
I got it to start today on only one mag. Maybe this means that I have a
timing fault.
If so how can I check ?
I flew today but between uncovering it and being ready to leave (see above
!) the blue sky disappeared and a 1300 overcast appeared. I ended up doing
one circuit (pattern). Air temp was 4 celcius (40 F) no misfire but I hardly
used a steady throttle ! I have fixed my throttle lever box problem and the
throttle cables are now pulling evenly. I haven't got the balance right as
it shook a bit at 5000 but was OK at 4800. However as in the past the
misfire problem seemed to "accumulate" - appearing on a second flight in a
minor way and on a third flight worse I need to fly more ! In each case in
the past the misfire went away after less than 60 seconds and a change of
throttle setting.
I live in hope that I have fixed it - probability .6 or 60% chance. (Sorry I
am a mathematician !)
Thanks for your help !
Richard
Richard F.W. Holder 01279 842804 (POTS)
Bell House, Bell Lane, 01279 842942 (fax)
Widford, Ware, Herts, 07860 367423 (mobile)
SG12 8SH email : rholder@avnet.co.uk
Europa Classic Tri-gear : G-OWWW, EGSG (Stapleford)
PA-28-181 : Piper Archer : G-JANA, EGSG (Stapleford)
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