I don't think I ever had a big-block MoPar that didn't do what you described
below...and it has been somewhat of a mystery to me too. I don't believe it
is directly carb related. It has happened on late-'60s and all '70s MoPars I
have had or worked on with all types of carbs.
The "too rich" theory? Fine,except that my '75 has a Holley that I put on it
10 years ago..and the carb has NO CHOKE. Mine starts well when
freezing-cold...then starts the chuga-chuga thing for a min..then clears up.
No stepping on the gas is needed to "clear it up"...sometimes.
When I asked an old mechanic about this about 15 years ago,his reply was
something pertaining to the temperature of the combustion chamber vs. the
mixture vs. the amount of raw fuel left due to improper combustion due to
the lower temps at start-up. Things change drastically and quickly when the
engine is warming up from very cold. What he said made sense..I hope what I
just wrote did.
He also mentioned that big block mopars in cold climates were known for this
"chugging"...and that their intake runner-flow and bad combustion chamber
efficiency while warming up added to the prob..making them suseptable to
this "flooding" syndrome.
I just use good spark-plugs...and don't let the car die when it is going
thru this warm-up "transformation".
Steve from Albany,N.Y.
'75 Imp 4dr <-chuggs a bit between 100`F and +\-140`F when started-up cold.
'79 440 powered 35 ft RV <--does the same thing as Brads NYB...but sounds
cool when it does it thru it's shaking,chromed,5 inch exhaust.
________________________________________________________________________
----Original Message Follows----
From: "Brad Hogg" <bhogg@xxxxxxxxxxxxxxx>
Subject: IML: Another Interesting Engine Mystery
Date: Sat, 12 Jan 2002 11:41:03 -0600
As long as we are sharing our various engine mysteries, here is mine...
I drive a 1978 with a 400 and when the temperature gets down close to
freezing, it exhibits the following. If you start the engine cold (and it
gets started cold every time because it has no block heaters) it starts VERY
well, runs for about 10 to 20 seconds (this time decreases as temperature
falls), and then it seems to begin missing on one cylinder and slowly goes
into this "woomp, woomp, woomp" mode. If the temperature isn't all that
cold, the engine will eventually straighten out and run fine. If it is
colder, the engine will eventually die. This is the strange part.
Regardless of the outside temperature, if I start the car, let it go into
it's "woomp, woomp" routine, and head off down the street, it will miss like
that all the way up until the point where the transmission shifts into
second gear. The instant it shifts, the engine runs perfectly and it will
do so from that point on, regardless of what gear the transmission is in.
Any clues?
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