IML: Pukey 440 Performance

["Eric" <gearhead@xxxxxxxxxxxxxxxx>]

Dave,
How old is the timing chain? That car would have the notorious nylon coated 
cam sprocket. Does a timing light show a jumping timing mark? If so, thats 
likely your trouble. My '72 440 Chrysler exhibited similar ailments: low 
vacuum requiring a full to-the-floor jab to get it off of the choke's high 
idle speed, rough idle, a slight surge at highway speeds, premature plug 
fouling, doggy performance. A new chain w/steel cam sprockets turned it into 
a silky smooth motor.When the valves aren't in time, they don't run well at 
all. My slant 6 Belvedere had a similar resurrection w/a new chain. My oil 
consumption even decreased.

As for the hard to reach spark plugs, I've found it helpful to remove the 
bolt that holds the bottom left motor mount and the lift the motor w/a floor 
jack a couple of inches to reach #7 plug, but I think the Imperials have 
more room with the longer wheelbase in that same vicinity of the vehicle so 
this may not be applicable.

I took off one head of my '63 Crown last year. The only real trouble were 
the 2 bolts that secure the exhaust manifold to the downpipe. They would not 
budge, even after torching. I ended up levering the manifold off the studs 
in the head and popped the head off the block. Rebuilding consisted of new 
valve seals and two valves that weren't quite as good as the others, and a 
hot tanking and some cleaning of the ports w/a wire brush on my drill. Very 
inexpensive, DIY in a driveway simple, and a lot less weight than an old 
straight 6 head.

The timing chain was about as much work, a harmonic balancer puller is 
needed and some minor crafting of the oil pan to front cover gasket is 
required. I'm now of the mind that it should be the 1st thing to replace on 
any old Chrysler w/a lumpy idle without any other malfunctioning indicators, 
aside from a jumping timing mark. The phenolic spacer under the carb also 
can produce a severe vacuum leak, I didn't notice it until I had it off the 
car but there on the unsee-able back side of it were any number of cracks 
causing a whopping vac leak. Your symptoms don't totally coincide w/a vac 
leak tho. The varying compression test would indicate an inappropriately 
variable valve timing. I'd check the timing mark with a timing light first 
to see if it holds steady or if a loose chain causes the mark to jump 
around. It's likely a simple fault and would be a shame not to take a 
week(end) and fix it and enjoy that big, beautiful facelift-fuselage 
Imperial.

Eric
Portland, Oregon
___________________________________________________________________
Date: Sun, 26 Jun 2005 13:44:04 -0700 (PDT)
From: David Duricy <desotobravo@xxxxxxxxx>
Subject: IML: 1973 Imperial Valve Job Questions
Reply-To: mailing-list@xxxxxxxxxxxxxxxx
My 1973 Imperial with 151,000 miles has been running
poorly. Symptoms have included lack of power, rough
idle, excessively noisy and hot exhaust, and low
engine vacuum (10 to 12 inches of vacuum on the worst
of days).

Compression tests show 120psi for cylinder 1, 90psi
for cylinder 3, and inconsistent readings for cylinder
5 - which jumps anywhere from 60psi to 80psi. With
these readings, I didn't bother to test the remaining
cylinders given how difficult it is to access the
plugs on this car.

I believe that the symptoms and the tests show that
the Imperial has either sticky or burned valves. I am
unsure what to do next.

Would it be more economical to have a machine shop
rebuild the cylinder head, buy a replacement head, or
attempt the work myself? I have done a valve job on my
1950 DeSoto, but I suspect the Imperial 440 demands
more skill and pricier parts than the DeSoto Six.

I'm wondering, too, if I should just sell the car.
That, however, is a very sad thought.

Your advice would be greatly appreciated.

Dave Duricy
1973 Imperial LeBaron (The Ailing Monarch)
1968 Imperial Crown convertible (The Usurper)
1950 DeSoto Custom (The Witness)



-----------------  http://www.imperialclub.com  -----------------
This message was sent to you by the Imperial Mailing List. Please 
reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be 
shared with everyone. Private messages (and attachments) for the
Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx
To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm