BobMGT@aol.com wrote:
>
> On a hot day, if I have a long wait at the stop light, the idle gets rough. If
> I wait long enough without toughing the accelerator, the RPMs will drop so low
> that the engine will stall. ... The temp gauge stays right on the 'N' at all
> times (new 190 deg thermostat). I don't think I have an overheating problem,
> but something here is heat related. I imagine the ambient air temp under the
> hood climbs when stopped even if the engine is not overheating.
Two things - it is quite usual for the revs to drop after idling for a
while, the manuals say to run the engine for 30 secs at 2500rpm every 3
mins while tuning, this is to 'clear its throat'.
Secondly the under hood temperature will increase which reduces the
amount of fuel/air mixture that can be drawn into the carbs due to the
lower density of air at higher temperatures. I used a cold air feed to
the air cleaner on a Marina many years ago, and swear it improved
performance. I also read many years ago that jet engines had distilled
water sprayed into the intakes at take-off to increase power, and one
crashed because the water was contaminated with oil (I KNEW flying was
marginal, but not THAT marginal).
Does it do it with the hood up, that is the question.
PaulH.
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