The engine is out and putting it back together so it can go back into the rebuilt body. Ready to put the flywheel back on and then the clutch. Want to make sure the flywheel is in the proper position. All I see is the arrow on the flywheel that is to match up with the arrow on the rear of the block for for timing TDC. I have both front and back pistons at the top. I thought I would set the distributor in and check to see if the rotor lined up with cylinder one or six. Then I noticed the drive dog on the bottom of the distributor is the same size on both sides and there seems to be a little play when fully seated. If I am not mistaken on later Jag engines, one side of the distributor dog is wider than the other so the distributor can only be placed in the engine one. So is it correct with an XK140 engine that the distributor can go either way because the drive dog or cog is the same size on both sides? Any advice on this and the flywheel installation would be appreciated.
Certainly on the early pushrod and sidevalve jag engines the dog was off set
Rehabs it has been replaced with a home engineered replacement.
We had a long discussion about this back in August/September 2016.
The driving dog has a very small offset, so one way is correct and it will drop in easily, but the other way will sort of fit if you really cram it in there. You can rotate the rotor as you go and feel that one way feels better than the other way, but the wrong way can be a fooler if you are not aware of it.
Next big question is, did you disturb the orientation of the 20 tooth drive gear in relation to the crankshaft? If so, your driving dog position may be wrong.
Last question, did you take the distributor apart? If so, the rotor position in relation to the driving dog may be wrong, 180 degrees off.
Follow the manual. Its all in there.
The drive dog for the XK140 distributor is definitely offset and is meant to fit into the engine one way only. I have a spare if you need one.
Should be offset on all XK engines 1949-1986.
And even if the 20 tooth drive gear were in the wrong location, it would not mean you had to take the engine apart to make it run, it would just change which distributor cap terminal you started with. The firing order would be the same.
Although you might have clearance issues between the vacuum diaphragm unit and the block if you are 180 out. I use a magneto, which has no vacuum advance, so I rotate it until the plug wires point in the desired location (side entry cap) then noting which terminal the rotor is pointing towards.
Thank Rob. I did not take the crank out or remove the oil pump. Only took
the sump pan off to have it repaired so the 20 tooth drive gear is
undisturbed. I recall the engine on my E-type having a very obvious
difference on the sides of the drive dog - one bigger and one smaller so
there is no way to get it wrong. This surprised me to look at this XK140
dog and into the receiver of the oil pump drive as it looks the same to
me. I’ve had the distributor in and it fits both ways. The engine seems
to have run fine before being removed from the car, but it never was reved
high RPMs. So now I am not sure about using this distributor and think I
should get another one. Thanks,
Mike. Thanks so much for the info and for the offer. This one must have
wear on the drive dogs because they look the same to me and the distributor
fits both ways. On my E-type engine there was a very noticeable difference
and there is no way one could get it wrong. I have several weeks/months
before needing this so will need to contemplate if I should order a new
Petronix or 123 electronic distributor or get this installed right and then
change it later. However, now I am concerned that when I look into the
receiver hole where the drive dog goes, that the recessed places look the
same. Must be a very small difference or perhaps they are worn and widened
out some.
Thanks again Mike.
Here is a photo showing the offset drive dog for the DVX6A distributor. The upper and lower drive teeth are off-centered to the left of the central shaft.
I think Mike and Mike and I are agreeing here, or finding different ways of saying the same thing. The driving dog really doesn’t get worn down, its just that the offset is very very small, so it is easily overlooked.
On an early Mk7 distributor I measure 5/32" from the center shaft to one side of the driving dog, and 7/32" to the other side. So the offset is only 1/32" from symmetrical.
I also measured one from a Mk1 and its the same.
I don’t know if they made it greater during the E-type era such that it would be more noticeable? I wouldn’t have thought so.
Since you did not disturb your 20 tooth gear or the upper rotor shaft in the distributor, it should be as good as it ever was before.
I don’t think you need a new one just yet.
Refreshing my old memory, I recall that if you try to cram it in 180 degrees off, the driving dog will sort of catch on the slot in the shaft, but the distributor will not go down all the way, not be seated right. You will feel the dog slip in when you get it right.
seems you have asked at least two questions…one re the drive dog, which as you can see on the photo is slightly off set…and helpful info posted. And…proper flywheel position…yes the arrow on the flywheel should align with the line on the bell housing WHEN #6 cyl (front) is at exact TDC : (This is your starting point for setting cams, timing.) BUT…NOTE BENE:You want #6 on TDC COMPRESSION…so important is that #6 can be at TDC at BOTH compression stroke (intake and exhaust valves closed and distrib rotor at / near firing of #6 dizzy cap/plug wire lead (near because you will later want to time dizzy firing to be some degrees (teeth) before TDC, thus 2-4 flywheel teeth before the arrow lines up.), IF #6 is at TDC on the exhaust stroke then exhaust valve open…and distr rotor not firing #6… You want the flywheel/bell marks lined up with #6 TDC on compression.
It makes no difference to the flywheel whether the 1 and 6 pistons are at the top of the compression or exhaust stroke since the flywheel is in the same position either way. Also, there are only two ways that the flywheel will fit on the crankshaft, so IT takes care of the exactness. If the pistons are close to TDC and the arrow is close to the mark then fit the flywheel where it fits.
Mike - thanks for the photo. That answered the question. What a subtle
difference. I looked closely at mine after looking at your photo and I
could see the offset. I thinking that one of the dogs or cogs should have
been wider or thicker than the other. I think that the way it is on an
E-type. If not I am getting scare over my confusion.
Again, thank you so much for your time and help. I’ll let you know what
happens.
Don
Rob - thanks again for this information. I no see the off-set on the dog.
What a small difference it is. I’ll try it tonight and see what happens.
Regards, Don
Nick - thanks for reviewing this information with me about the flywheel
installation. Seems like I always get confused about number 1 and 6
cylinders and which one the timing is set by. Now that I have the proper
info and the distributor dog off-set, I’ll be able to put in the the
distributor with cap and make sure I have the flywheel arrow aligned with
the bell housing while #6 is on the compression stroke with the dizzy rotor
pointing to #6 plug wire.
I know this is pretty fundamental stuff, but if you don’t do it very often
(or get old in the meantime) its always great to have a review by the Jag
brain trust on this forum.
Thanks to you all for reviewing this with me.
Best Regards, Don
Thanks Mike. I kind of thought this, but if the timing mark on the
balancer is on 0, and the flywheel arrow is lined up, would not the No. 6
piston be TDC on compression?
It could be on compression or it could be on exhaust. The flywheel is connected to the pistons. It is in the same position whenever a piston is up, and it doesn’t matter WHY the piston is up. If the flywheel is at the mark on the compression stroke and you turn the flywheel 360 degrees so it is on the exhaust stroke the flywheel will again be on the same mark. That’s why it doesn’t matter whether you time your engine on cylinder 1 or cylinder 6. The flywheel is in the same place for either power stroke.
Thank you Mike. You could have been a technical writer. I appreciate it.
I just put the flywheel in place with the dowels. Now I find that when I
hammered in the new pilot bushing that I caused some damage to the outer
circle and the pilot shaft for the clutch alignment won’t go it. So I am
going to use sand paper and a small file to make the opening true again. It
took me forever to get the old bushing out. I went to three places to get
a removal tool and none of them worked. Ended up using a hacksaw in two
places and then prying it out. Should a 15 minute job, but took hours with
all the running around for the right tool. Its one thing, then another
… but sooner or later, usually later, the job gets done.
Best Regards, Don
as others have suggested,do have the full Jaguar Shop/Service Manual.
(available in reprint copies on ebay etc for not too much…(don’t pay the
inflated prices…shop around.)…For the XK140 it will be the 120 / Mk7 manual
with the supplement pages for 140/150…and it is a good idea to get the set of
Technical Service Bulletins (TSB) that cover xk120-150…harder to find but
available…many things changed thru the years…many parts or specs
superceded…often mandatory in a rebuild. Nick
In a message dated 4/19/2017 1:22:39 P.M. Pacific Daylight Time,
noreply@jag-lovers.com writes:
_etch_ (http://forums.jag-lovers.com/u/etch)
April 19
Nick - thanks for reviewing this information with me about the flywheel
installation. Seems like I always get confused about number 1 and 6
cylinders and which one the timing is set by. Now that I have the proper
info and the distributor dog off-set, I’ll be able to put in the the
distributor with cap and make sure I have the flywheel arrow aligned with
the bell housing while #6 is on the compression stroke with the dizzy rotor
pointing to #6 plug wire.
I know this is pretty fundamental stuff, but if you don’t do it very often
(or get old in the meantime) its always great to have a review by the Jag
brain trust on this forum.
Thanks to you all for reviewing this with me.
Best Regards, Don
Don,
I use 1/2" bolt and heavy grease, old can on Texaco Marfax Heavy Duty 2 grease, and have never failed to remove a pilot bushing. Pack the hole about half full of the grease, insert the bolt and usually a few taps brings the bushing right out. Take the same bolt and cut the threaded part off and it leaves you with a handy dandy bushing driver to install the new bushing. This method of removing a bushing in a blind hole probably goes back a 100 years.
Bob
889076
Plymouth, Mi