Sir
From the ( 1966 plus ) "normal" 350 horse powered 440 with an
single exhaust and the single snorkle air cleaner housing, the "HP" version in
Imperials was the exhaust manifolds that permitted the exhaust gasses to exit
the heads in an better manner to the dual exhaust system ( dual exhaust pipes
to dual mufflers and dual tail-pipes ). To all that follow power
information of the V8 engine, this is the biggest "bang for the buck" item
that one can do to add power to any year and any make of "V" designed
engine. Sooo, if you have an Imperial V8 of any year just going
from the factories " save a nickel with production cost " with having an
single exhaust, to add an profit by charging more to add the dual exhaust, you
too will have the same power the clothe top Imperials have. ( ... Before
the days of the Road Runners, GTX's and the such they just had dual exhaust on
the exhaust manifold that all vehicles got ).
An item to keep in mind is to only have the exhaust pipe the same inside
diam of the exhaust manifold to the muffler of the same size. For the
driving that most Imperialist Driver's do, to have an exhaust cross-over pipe
connecting the two sides at the notch between the rear of the engine and
the bell-housing is the best set up. For those who know the Imperial was
an lux prestiege car for upper class owners who liked the style of the
Imperials road abilities, to have an "X" instead of the cross-over will permit
a better power, emission and audio of the basic system.
And in all Chrysler Products of the time, if it had dual exhaust, it had
an dual snorkel intake housing.
With the same 440 cubed 375 horse powered engine ( Imperial Speakie
since lower classed Divisions had the 383 with 335 hp ) which also came an cam
shaft of different spec's ( P4529270 ), and valve spgs that had an higher
pressure rating. This permitted the engine to get its power at an higher
winding ( rpm ). Many Imperial owners who are re-building their 413 or
440 cubed Imperial want to use this cam cam assembly but fail to realize the
now made MoPar cam assembly P4286675 is better suited to the weight and all of
the Imperial.
Before the above mentioned 1968 exhaust manifolds and cam assembly used,
the 1966-67 440 was rated at 365 hp with just the twin snorkels and dual
exhaust. The 1968 intake manifold was redesigned, the AVS carb's were
also changed to the newer style/design of the "spread-bore".
The same rebuilding or just retro working person who has an
1966 -1959 Imperial does not know the GTX, Road Runner rear dumping
exhaust manifold will never work on the drivers side of the engine.
In order to get the same level of performance they must use a pair of the
later to be used 440/400 1972 to 1978 Dodge Truck exhaust manifolds(
http://www.1aauto.com/1A/ExhaustManifolds/Dodge/PickupFullSize/1AEEM00081/67558/ ).
I re-wrote what Eric was speaking about so that any "newer" Imperialist
will have a short speed course of the subject.
The 66 Le Baron taking up space here has the "X", true 1969 MoPar
Performance Muffler's and Resonator's to keep away that "GTX" sound behind
stock exhaust manifolds. The other car ( 62 Crown two door ) has the
1978-1972 mentioned exhaust manifolds, the cross-over and the same exhaust
from the same mufflers to the same resonators to the same infamous "MoPar
hook" tail pipes. They are both as quite as an Imperial at the gates of
the local "Country Club" and are able to pull the vintage Air Stream with
gusto up the passes here in Colorado.
If I ever wear out either of the above I will use the same 1972-78 Dodge
440-400 truck manifolds ( remember 1959 to 1966 Imperials ), an exhaust pipe
of the same size from the right to an dual in-let muffler of the same diam on
the one side and an equal size exhaust pipe on the driver's side that will
have an "lazy S" to the left in-let of the muffler to an single out-let tail
pipe. This designed system has been dyno proven with OEM Dodge SRT
trucks that are also performance proven.
I do not like added chrome under the hood, flex cooling fans, and the
after market radio cut into the dash. Or, tubed after market headers and
mufflers that sound much in the same audio levels as an logging
truck.
About three years ago I spent a lot of time inspecting an OEM 375 horse
powered 1968 Imperial Crown four door in Denver. Since the Imperial
was at an "All MoPar Car Event", the owners just stayed in the eazy
chairs and let me look all over it.
Some of the other hard to find items on Imperials are the 3.23/3.32:1
ratio Rear Axle assemblies, Sure-Grip, OEM Power Steering Aux Cooler ( looks
the same but has an different sized mounting bracket than an NY'r ), OEM
Transmission Aux Cooler and the factories spec'd towing hitch. One
needs the Factory Service Manual and that years Parts Catalog or in
towing, the Towing Suppliment Data, to make sure.
Rodger & Gabby
COS
----- Original Message -----
Sent: Wednesday, July 25, 2007 6:50
AM
Subject: Re: IML: 440 Hi-Output Vs.
'normal': Thanks Eric!
In a message dated 7/25/2007 7:46:10 A.M. Eastern Daylight Time,
YBSHORE@xxxxxxx writes:
Imperialists:
The only
difference I find between the two motors, besides the dual snorkel,
are that the TNT came with duals, rated to 375HP, and the 'basic' 440 did
not have that exhaust system and was rated at 350HP. After reading
Uncle Rodgers' post's for years about 'getting more out of a car' in
regards to a dual exhaust system by matching the outlet to the pipe
size,etc., and letting these ol' girls breath, thus giving it the
extra 5% to 10% gain, I am wondering if "HP", really meant 'factory stock
duals'?
Jack
The
440 Dual option was not an engine package as such, but a standard 440
with the addition of a dual snorkel air cleaner and dual exhaust. The
horsepower rating for this option raised the standard figure from 350
to
360. The high performance 440 TNT/Magnum/Super Commando differed in
these
areas as applied to C-bodies in '68:(Imperial now being a
C-body) Carter
carb #4429S in place of Holley, H.D. valve springs,
special cam, 268-284-68
in place of standard cam 256-260-32, dual
point distributor instead of
single points, upswept exhaust manifolds
instead of log type and a windage
tray for the oil pan. This engine
was available for any C-body except
Imperials and wagons; which also
had the standard 440 twin snorkel/exhaust
option. This was a one year
only deal for the Imperial ('68) but was a wagon
option for many
years. Chrysler never even bothered to note the option
raised the
gross h.p. by 10 in wagon literature but hyped it up in the
Imperial
catalog. What a shame the 375 horse 440 was not an option-it sure
should have been. It is my feeling that with the typical fastidious
Imperial
owner, the twin snorkel/exhaust thing may fly under his
radar, but the
rumpity-rump 375 horse cam would have been too much!
BTW- v.i.n. code for
350/360 horse 440- K vs. L for 375 horse
440.
Eric S.
'65
Crown
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