IML: Part Throttle Spark Knock on 440

["Sherman D Taffel" <staffel@xxxxxxxxxxx>]

Hi Jay!
You mentioned Motor Mounts and the #8 plug maybe shorting.

On our Jensen Interceptors it is quite common to have the left motor mount
become 'torn' over the years from the Torque of the engine.
My1st evidence, after I bought the car,was  noticing  a slight scraping on
my bonnet frame 'structure' from the 'vacuum flap 'pot' on the twin snorkel
of the Air Cleaner. I also had an slight exhaust to body contact upon
acceleration.  Use a floor jack with a 1/2" square of plywood under the oil
pan, and 'just take the weight off the engine so the mounting bolts will
slide out. You have to tweek the pressure ever so gently.

On the big Jensens the rear plugs (#7 & #8) are almost impossible to change
without special sockets or wrenches- The manifolds actually 'touch' the
inner fender wall insulation-thats why the side vents and bonnet loovers).
You don;t have that problem in the giant engine bays of the Mighty Chryslers
and Imperials.

However, to your pinging. Sometimes the mechanical weights -the advance
mechanism in the distributor 'stays stuck' and therefore keeps the timing
advance 'more advanced' than 'required' for the mid-RPM range. The vacuum is
more of a 'retard'. The best timing adjustment for performance has always
been to advance the distributor till ping at the shift point, then retard a
hair at WOT RPM for the 1/2 shift. The Jensen has the same 440/727 2.93 rear
end as Imperials. Not 'fast' off the line-also a refined touring motorcar,
but when all is right even at 4300#, that 1/2 shift should give a 'chirp'.
And I don't don't do it often, as I am gentle with this and my other cars.
So that's one thing you might want to  look at!
I am also curious as to why you chose the Edelbrock 1406 at 600cfm. Most of
us 'Jensenites' have upgraded the Thermo-Quads with the plastic problems to
Edelbrock 1905's (Still available) that were rated 795 CFM. Noww people are
using the 800CFM's.  Same dependable 440 engine! One thing I did when I
rebuilt the 727 tranny, was install the 'Road Runner' Valve Body upgrade-
much sharper shifts. The 727's in these cars were never 'sloppy' like GM
Hydro-(washingmachine) -matics  --trannys of the era, but for extending band
life and the weight of these cars, the valve body upgrade 'couldn't hurt'.

Sherman D.Taffel
Columbia, MD

'Imperial in the Spring'-(details when appropriate)
'56 Dodge Coronet 270 Poly V-8
'70 Jensen Interceptor I Restoration Project (383 Magnum)
'74 Jensen Interceptor III Convert (>3,000 mile in '04,'03,02,01, 6,700
Cross- Continent miles in '00)
'89 Dodge Daytona Shelby (since new)
'96 3.8 Caravan ES Touring (Wife's)
'03 HEMI RAM-Laramie 4x4
4 Jags, 4 Jensens, TR4





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