Today's Message Index:
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1. 11:19 PM - Rough running Jab 3300 (Gary Eady)
2. 11:36 PM - Re: Rough running Jab 3300 (Paul Mulwitz)
Message 1
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| Subject: | Rough running Jab 3300 |
I'm having a few issues with my Jab 3300 solid lifter engine. Intermittentl
y, normally under load in the climb, it develops a miss in either one or ot
her of the front cylinders. The miss/rough running only lasts between about
10 and 20 seconds and recurs every couple of hours or so of flying - but i
s enough to make me look around quickly for an off field landing area.=0AHa
ve checked the resistance and condition of the HT leads and also the coils.
All seem to be ok.=0AThe errant cylinder is easy to track via the EGT prob
es and is always number 1 or 2 which is suddenly about 100 degrees C cooler
than the others.=0AThe engine has 70 hours on it and starts well hot or co
ld - is burning no oil and throws virtually no oil into the breather bottle
.. All engine parameters are great including cylinder head temps. Except for
this darn miss.=0A=0AAnyone else out there having or had a similar problem
??=0A=0A=0ARegards=0A=0AGary=0A=0ACH701,- Jab 3300A serial number 500, 70
hours total time. Grand Rapids EIS.
Message 2
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| Subject: | Re: Rough running Jab 3300 |
Hi Gary,
First let me say I am no expert on engines of any sort. So don't depend
on my being right.
I once had some strange miss-firing because the carburetor was loose.
It was more dramatic than your story and only went bad when I reduced to
idle power for descent.
The thing that comes to mind listening to your story is you are at a
high angle of attack. That suggests there is something about the air
flow to the carburetor might be funny. In my plane I took extra
measures to straighten out the air flow just in front of the
carburetor. There are several ways to do this, and I don't really know
if any are necessary.
A 3300 is a large engine for a 701. You must get very high pitch on the
aircraft nose when climbing. This suggests a possible problem with fuel
pressure could be involved. Do you have a boost pump?
Good luck,
Paul
Camas, WA
Zodiac XL, Jab 3300
On 2/6/2014 11:16 PM, Gary Eady wrote:
> I'm having a few issues with my Jab 3300 solid lifter engine.
> Intermittently, normally under load in the climb, it develops a miss
> in either one or other of the front cylinders. The miss/rough running
> only lasts between about 10 and 20 seconds and recurs every couple of
> hours or so of flying - but is enough to make me look around quickly
> for an off field landing area.
> Have checked the resistance and condition of the HT leads and also the
> coils. All seem to be ok.
> The errant cylinder is easy to track via the EGT probes and is always
> number 1 or 2 which is suddenly about 100 degrees C cooler than the
> others.
> The engine has 70 hours on it and starts well hot or cold - is burning
> no oil and throws virtually no oil into the breather bottle. All
> engine parameters are great including cylinder head temps. Except for
> this darn miss.
>
> Anyone else out there having or had a similar problem??
>
>
> Regards
>
> Gary
>
> CH701, Jab 3300A serial number 500, 70 hours total time. Grand Rapids EIS.
>
> *
>
>
> *
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