Hi everyone,
Most of the followers of this list are pretty familair with the sad tale
of Dave’s non-starting MKX. For those of you that aren’t familair with the
story its one of him swapping a 72’ XJ6 engine into his 62’
MKX. By the way the car was nicknamed Moby Dick as its a large white car
and not unlike the book where Captain Ahab was tormented by Moby Dick
poor Dave too is being driven crazy by this car.:-).
A little history: Dave’s MKX original engine was running but had low
compression so he bought an engine that was in a 72’XJ6. The engine was
reported to have been rebuilt about 2800 miles ago. Dave installed the
engine in his car using the starter that came with the 72’ engine as the 62’
starter didn’t have the correct reach on it. Once the engine was installed
he started it and the car ran for a few seconds at a high
rpm and then died. Since then it hasn’t wanted to start at all. It just
turns and turns…
Now a few of the points that are known:
(A) The compression is good across all cylinders
(B) Fuel is getting to the carbs,(dual Strombergs)
© There is a good spark at all the plugs.
(D) The car when turning over seems to get hung up on the 6th
cycle of starting then free up again till it gets to the
next 6th cycle. (Sounds like the starter gets dragged down)
With the plugs out the engine turns on the starter freely
without any bogging down.
(E) Engine came from a negative ground car.
(F) If the distributor is turned a bit the engine seems to
want to start but sounds like its popping and
backfiring.
(G) The starter is turning the engine the correct way.
(H) The battery is fairly new.
(I) The MKXs battery was originally negitive grounded when
Dave got the car and had it running with the
orginal engine.
(J) The car won’t even fire over with the use of starting
fluid in the cylinders or through the carbs.
(K) The carbs have since been rebuilt and a second set from the
old engine was put on as these were known to work.
Now a few questions of the unknown:
(A) Daves radio is/was a positive ground…he’s
never heard it work since he’s owned the car.
As it did run with the battery with a negative
ground since Dave first had it can the assumption be
that this car has been converted to negative ground?
His fuel pump is aftermarket as well. How can one check
to see what a cars polarity should be?
(B) The 72' engine was/is set up for an alternator but the
engine was sent without one so he put the generator
from the 62' in its place. Does this seem like it
would work? He did try to start the car with the
wires from the alternator not hooked to anything but that
didn't seem to change anything. Do you need to go with
an alternator with this engine?
(C) Has anyone done an engine conversion with a different
polarity?(possible in this case)
(D) How do you check for proper polarity for engines and
the such? And what needs to be done to get all the pieces
in line?
From all the conversations I’ve had with Dave over the phone, on the
jaglovers chatroom, and e-mails it seems that this is a grounding
problem if not a mixed polarity issue. The reason I’m posting this is
I’ll be going up to see him in a few days time and I’d like to get as
much info as I can regarding this. By the way, I suggested to him to get the
starter checked out just to make sure it was up to the task.
Dave has gotten this far with the car and I’d hate to see him give
up on it at this point so any help would be a big help. I did tell him
that to solve this problem he should buy another jag,
Chris Burdo
1965 3.8s(MOD)
Canterbury,Connecticut,USA________________________________________________________________________
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