Petronix ignition issue


#1

A PO replaced the points system with a Petronix ignitor system on my 1971 4.2 litre and I have never been entirely happy with it. The distributor seems to be in the wrong orientation - the vacuum capsule pointing obliquely towards the block where it fouls the heater pipework when turned to the correct ignition timing position. I suspect fitting the ignitor pick up and magnetic cam sleeve has somehow altered the point at which the spark occurs necessitating rotation of the distributor to its present orientation to compensate.

I have tried moving all the HT lead connections round one hole and turning the distributor to compensate (60 degrees) but that is too far and the dizzy then fouls the water pump connections. What I really need to do is turn the distributor to advance by about 20 degrees whilst retaining the original timing set up. I can do this by moving the drive by one or two teeth but that means taking off the sump……….

If I re-drill and re-position the pick up base plate to retard by 20 degrees and then rotate the dizzy to compensate by advancing 20 degrees I am back where I started and have not changed the timing but will have a better orientation for the vacuum capsule. However, the position of the HT terminal contacts will have changed relative to the spark.

Any suggestions?

Frankie


(Erica Moss) #2

Do you have a micro adjust knob like on my 22D dizzy? You have a lot more than 20 degrees of range with that. There are over 60 clicks total available range on mine at I think 2 clicks per degree?

On my e-type, with the micro adjust centered it’s the points which aim the vacuum capsule diagonally towards the block and the igniter rotates it anti clockwise so that it’s parallel with the block (yes I think it’s because the pickup isn’t right over the cam lobe.)


(Frank Andersen) #3

This is basically a matter of the mesh with the distributor driving gear, Frankie…?

When the distributor was fitted it meshed in the ‘wrong’ position - and can be lifted and reoriented. 20 degrees would be a tooth or two…?

Frank
xj6 85 Sov Europe (UK/NZ)
**

Frank
xj6 85 Sov Europe (UK/NZ)
**


#4

The micrometer is set at the middle of its range. I didn’t realise such a wide angle of adjustment was possible with it - I will try that today.

Frank - you may well be right. The drive at the base of the distributor is an offset dog - so the “mesh” there can only be altered there by one complete revolution of the distributor. The gear drive of the shaft below that comes off the crankshaft and to alter that mesh I thought you had to take the sump off. Is it possible to change the gear mesh from above?

Frankie


#5

I’ve just been out there and checked again. The micrometer is already fully advanced (forgot I did that last time I tried to adjust it) and looking down the well at the head of the drive shaft in the block I can’t see anything to grip hold of to pull it up and turn it to re-mesh. I’m reluctant to disturb anything I can’t put back easily.

Frankie


(Mike Balch) #6

Take a look at page 20 of the Lucas Overseas Technical Course for Coil Ignition. If you remove the drive dog from the distributor shaft, re-position it by 20 degrees on the shaft, then drill a new hole for the pin, wouldn’t that solve the problem?


(Erica Moss) #7

So if you set the adjuster wheel back to the center (about 32 clicks on mine) and reposition the wires on the cap to where they should ideally be, does that not bring the dizzy to the correct position?


(Frank Andersen) #8

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Negative, Frankie; it requires dismantling as you say - I had a senior moment there - old habits die hard…:slight_smile:

The problem may have been initiated during assembly, or reassembly - getting the driveshaft mesh wrong. Your original suggestion, redrilling the shaft has merit, but requires considerable precision…

However, nobody has mentioned similar problems when converting to the Pertronix. I wonder if Pertronix has dogs with different angles to cater for variations? Or, more unlikely, possibilities for internal adjustments? As there is no emergency - contacting Pertronix may be a good idea?

Another possibility is to fabricate a new dog with a better angle - it’s less destructive if you misdrill the shaft of the expensive Pertronix. A third possibility is to weld the dog to the shaft…:slight_smile: Further; comparing the dog of your old distributor, or another dist, to compare it with the Pertronix one?

With my set-up; the vacuum capsule is basical ‘for-and-aft’ with the capsule rearwards. I wonder if somehow the ‘advance’ versus the ‘retard’ vacuum is raising its ugly head…? Though I suspect the Pertronix is an ‘advance’ unit…?

Frank
xj6 85 Sov Europe (UK/NZ)
**


#9

Mike - what a marvellous old publication - thanks for that.

I have replace the hose from the back of the water pump with a shaped hose and found sufficient slack in the heater pipe running under the inlet manifold to re-route it under as opposed to the previously over the vacuum capsule. This has eased the conflict - the capsule and pipe still touch but not as heavily. The photo below shows it after this adjustment.

Thanks for all your input

Frankie


(Carl Hutchins, Jr. ) #10

Frankie:

  1. Kudos on a solution that does work aka “work around”.

2.Teh picture clearly depicts the situation that prior print sought to describe.

3, IMHO, something down in is 180 degrees ought of phase. So, the installation of the distributor 180 out of it’s intended location conforms. It works.

  1. I just looked at the location of the vacuum can and the red wire and mentaly spun them 180. eureka, it fits just right.

  2. A neat part, albeit. Bye bye points !!!

Carl


#11

Interesting observation, Carl. Nowhere have I found a photo or diagram from Jaguar that shows the “factory” distributor orientation in context. I have looked at many XK engines over the years and there seems to be no consistency of orientation. Might be interesting to hear what others have in their engine bays.

Frankie


(Pete55Tbird) #12

Frankie, I put a Pertronix distributor on my 67 420 compact sedan with a 4.2 and I remember the drive “dog”
would only engage ONE WAY and not 180.
Mire runs great and the vacuum can is rotated COUNTER CLOCKWISE 40 degrees from the posted picture. Pete
PS Summit Racing sell the PERTRONIX distributor
https://www.summitracing.com/parts/pnx-d41-05a?seid=srese1&cm_mmc=pla-google--shopping--srese1-_-pertronix&gclid=CjwKCAiAuMTfBRAcEiwAV4SDkWObnzfb5C38fWiuehCI_VoUj5fldtL3ZClQMx5JnR5IzMszyEdVoxoCVPAQAvD_BwE


(Frank Andersen) #13

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Carl’s point is well taken, Frankie…

Looking at the picture; there is plenty of room for the vacuum capsule with a suitable counterclockwise rotation. The only requirement when positioning the dist is that with the engine at TDC- the rotor must point to the #1 cylinder plug lead.

Or put another way; before the dist is removed from a properly timed engine; engine should be placed a TDC. Then the rotor position noted - it will point either to the #1 or #6 cylinder’s plug lead. When the dist is reinstalled it can be rotated and positioned any which way - but(!) the relevant plug lead (1 or 6) must be put put into the dist connection the rotor points to. Ad the rest of the leads placed conterclockwise from there in the ignition sequence…

Where things may go wrong is usually when the head is taken off (of course after setting the engine to TDC). When the head is replaced with correct valve timing; #1 cylinder automatically becomes the refence cylinder - and the dist rotor point to the #1 plug lead. If the engine was on the ‘wrong’ TDC, and if the plug leads were replaced, or kept, in the original position - timing will be 180 degrees out…

Adding that, for whatever reason, some POs reposition the dist - which is perfectly OK if the plug leads are moved accordingly. Hence the variations in the vacuum capsule alignment - hence there are no ‘factory’ position; they assumed people knew what they were doing.

Imitating someone else’s dist position without understanding the principles leads nowhere. Simply; the rotor must point to the cylinder that is ready to fire - dist orientation beyond that is immaterial…:slight_smile:

And I should damned well have cottoned on to your problem initially, sorry…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
**


#14

Well, I’ve tried turning the dizzy 30, 60, 90, 120 degrees and although it may not look like it from the photo it either fouls the heater pipe, steering pump or water pump. I guess some nit-wit just meshed the drive from the crankshaft wrong on earlier re-assembly. I’ll put it on my list of work for the next “engine out” job. The joy of old Jags!

Frankie


(Carl Hutchins, Jr. ) #15

Frank:

No need for "sorry … cottoned ". For me it was Frankie’s picture that told the story. The adage of pictures and words remains true…

Frankie:

  1. Leave it be. It runs well. do not fix what does not need fixing.

  2. Go back in at a bit of peril, but with a path back should it not work out

If the shaft will engage 180 Degrees away from present, change it. As Frank says, the rotor will be 180 out. The fix. move each HT lead to a post 180 away.

For the sake of reference, have the TDC at the “fire” TDC… And the rotor at #1. In jaguar speak, the one at the fire wall end of the engine!! In USA critters, we think #1 is at the radiator end. No matter, the critter at hand is not a USA critter…

Carl


(Pete55Tbird) #16

Frankie; Please step AWAY FROM the CAR. Time-out. Check the archives of the XKE on distributor on how to properly install a distributor. Number one piston ( the piston closest to the back of the engine) at TDC AND remove the oil filler cap from the cam cover and see the lobe of the camshaft pointing UP.Now put the distributor into the engine. Pick # 1 cylinder on the cap and follow the firing order ( I believe CC counter clockwise, PLEASE CHECK. Let me know how it looks. Pete


(Frank Andersen) #17

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What actually fouls what, Frankie…?

There seems to be plenty of room for the vacuum capsule (now at ‘1 o’clock’) at around ‘5 o’clock’. However, the vernier adjustment may be the problem - it was not fitted to most distributors…?

Since the engine is running(?), what is the actual problem with the timing - and what is the present advance setting…?

Frank
xj6 85 Sov Europe (UK/NZ)
**


#18

Pete.

I recently re-timed the valves and can confirm that the crankshaft pointer is correctly positioned, at crankshaft 0 degrees the cam setting tool engages perfectly with both camshaft cut outs and the rotor points to No1 (rear cylinder) HT lead contact.

Frank.

Present advance is 20 degrees at 1,700 rpm with vacuum advance disconnected. The timing mark is clear on tick-over but becomes blurry as revs increase - I have set it as near to the centre of the blur as I can.

As I rotate the distributor body clockwise to try and pick up each cap terminal position in sequence (60 degrees apart) the first foul is the cap spring clip against the water pump (the clip position becomes the wire grommet position in the photo); the next two fouls are the vacuum capsule against the steering pump (at bottom of photo); then the water pump against the capsule. I can understand your puzzlement based on the photo but the least troublesome position is the one shown - not perfect, but good enough for the time being. The engine runs fine, my niggle was that the capsule pressed against the heater hose but I have eased the pressure by replacing the hose and adjusting the pipe.

I had the distributor rebuilt earlier this summer by a v reputable specialist in the UK (Distributor Doctor) and he says its assembly is correct (and it is the correct dist for the engine) so by process of elimination the issue must be gear mesh.

Frankie


(Pete55Tbird) #19

Frankie, please let me take a second pass at this distributor installation in relation to item that interfere with
with you ability to rotate the DISTRIBUTOR HOUSING ( not the shaft that the rotor is mounted on ) to adjust the timing. The rotor and the shaft and the drive tongues that engage the dog drive rotated by the crank
ARE INDEPENDENT of the DISTRIBUTOR HOUSING.
Set TDC
Drop in the body of the distributor housing BUT do not engage the drive dog of the rotor shaft.
Position the distributor in a PLACE OF YOU CHOOSING
Rotate the rotor and shaft UNTIL the tongues DROP INTO the DOG Drive
Where your rotor is pointing IS NOW NUMBER ONE
That’s it


#20

Hi Pete.

I’m afraid I must be away with the fairies here - I don’t get it…If I do as you suggest I can see that the rotor will be pointing to where No 1 contact needs to be; problem is that when I fit the cap (will only fit one way) the rotor won’t align with any contact in the cap. The car is up the air at the moment with the suspension being overhauled - I will try your suggestion when its back at ground level and let you know.

Cheers

Frankie