Not on XJ’s and E’s. One side of the dog drive is thicker.
A compression gauge will not be very helpful in determining the compression stroke. It will be enough to put a finger on the spark plug hole while turning the engine or just have a look inside. On the wrong stroke you should be able to make out the valve. If not, cam position might be visible through the oil filler hole, or you could blow air into the cylinder and see if it leaks out.
With the cap installed and the distributor loose it would be easy to find out if the spark goes to the right cylinder and thus rule out a misinstalled drive gear, but I understand your decision of letting someone else have a look.
David
By the way, I can see no way that an engine would be running at all with the ignition 360° out?
I realise that the dog drive is thicker / wider on one side than the other. My question is can the dog drive be fitted to the distributor shaft with the roll / locking pin one way only, or is it possible to fit it in reverse, that is 180 deg out from original specification. I have two distributor ‘specialists’ saying each other is wrong. Is the pin holding the dog drive on to the distributor shaft off-centre or in the centre of dog drive? What is the direction your rotor - brass end pointing - in relation to the thick / wide side of the dog drive on your distributor?
Cheers,
Tim
The two times I had a distributor in my hands it would only go in one way. This is for later 4.2s of course. It doesn’t matter (unless you aim for perfection), as long as you can verify that the rotor sparks to the corresponding cylinders while these are on the compression stroke. Personally, I would put a sheet of foil over all spark plug holes and place the corresponding plugs next to them. Where the foil is pushed away, the spark should occur; this would verify good timing and plug wiring at the same time. It seems like you have done all you can and your timing is not the problem. The distributor sparks when it should so the rebuild must be okay?
Is there anything else you might have missed or disturbed during the installation?
Good luck.
Thank you for that Ian, it’s so helpful. What book does it come from? My issue is that I took my distributer to a recommended ‘specialist’ in Melbourne only last Friday who said that the dog drive was 180 deg out. He took it and said that he had to run a drill through the hole where the rolled locating pin goes through the dog drive to make it fit. My heart sank at this news but I was stuck. The fellow who rebuilt the distributor said that the dog drive can only go on one way on the distributor shaft as it’s off-set. Having to drill it out to fit the pin might indicate that this is indeed the case? I fear that the recommended ‘specialist’ may have ruined my distributor! All I want to know now is if the dog drive pin is off-set like the drive itself as I can see in your diagram? I’ll pull the distributor out tomorrow and have a close look at it. With your diagram I will be able to quickly determine if the ‘specialist’ in Melbourne was correct or has just ruined my distributor?
Cheers,
Tim (so fed up)
Hi Ian, I knew I had seen it before. Page 62 of the Service Manual. The old brain just can’t hold everything in anymore. However, I now have the information to hand. All I can think is that I will be able to help so many people in the future with similar issues.
I’ll still be very cross if the ‘specialist’ has ruined my distributor.
Cheers,
Tim
By my reckoning the rotor should be pointing in the direction of the locating bolt hole of the distributor clamp / pinch plate? It will also tell me if in a previous rebuild of the engine the timing is out by 180 deg as Paul has experienced.
The firing order is 153624. Turn the engine over until you’re at TDC compression on #1. Wherever the rotor is pointing is where the wire for #1 must be connected. Connect the other 5 in order.
Set your static timing.
Go for a drive.
Having the drive dog out by 180 (or the driving gear out) doesn’t make any functional difference as long as the spark arrives at the correct piston and follows the correct order.
Yes Andrew (Isambard Kingdom Brunel ), I’m across the firing order. My question remains, is the drive dog able to be fitted on one way or two. That is, is it offset or not?
The dog is always asymmetric. It’s possible to fit the dog 180 degrees out on the shaft, but that involves driving the rollpin out-someone may have rebushed your distributor and fit the dog 180 deg out, but the holes for the pin are usually a bit off center, so you have to struggle to get it aligned incorrectly.
And that would explain why the ‘specialist’ had to drill out the hole, thereby ruining my distributor. That arrogance on behalf of the ‘specialist’ makes me very cross.
It isn’t ruined because the dog is out by 180 degrees.
Now, if the rest of the rebuild is also bad, then it may well need some “wellness” to get it back to original.
Of the possibly 200 XK engines I’ve worked on, about 4 or 5 of them had the dogs fitted the wrong way around. You just have to connect the wires 180 degrees out of what the shop manual says and the engine will run just fine.
And nothing is ruined. If the distributor was rebushed the rollpin was out before. Either way, 180° out or not, as we said a simple verification that the sparks happen on the correct stroke will do and you can rearrange the leads 180 if the drive clutch is actually out.
Andrew: if was 180° out, it won’t run, but it did. Is that not wrong?
David
Here is mine off a 140 . Although I have not removed the dog I would say the pin is central so could go on either way. Surley if it’s 180 out, just move your cap wires round 180 to make it work , but best to establish exhaust or inlet .
Okay, last thought before I go to sleep. In Andrew’s diagram number 6 cylinder is 180 deg out from the four XK engines I’ve looked at this weekend. The four had number 1 where Andrew’s diagram shows number 6. On the XK engine number 6 is the front of the motor and number 1 is the rear. Would people confirm this by looking at their cars please?
Tim
All I want to know now is if the dog drive pin is off-set like the drive itself as I can see in your diagram? I’ll pull the distributor out tomorrow and have a close look at it. With your diagram I will be able to quickly determine if the ‘specialist’ in Melbourne was correct or has just ruined my distributor?
), I’m across the firing order. My question remains, is the drive dog able to be fitted on one way or two. That is, is it offset or not?
