Hi all,

Does anyone know of a competetent Jag XJ6 (series 2) mechanic in or around Buckinghamshire UK ? I have a couple of issues I just can't resolve myself. Any recommendations much appreciated !

Well, I found one straightaway via a Google search, but whether they're competent, I haven't a clue as I live near Crewe !
https://ajfmotorengineersltd.co.uk/p...engineers-ltd/

Many thanks Fraser, looks like a good and long established organisation who also deal with classic cars which is quite rare. I'll give them a call !

Perhaps post the issues on here, there are some very knowledgeable forum members and at least you will be forearmed when you talk to a garage and it’s remarkable what people can diagnose from across the channel, pond and the other side of the world!

Hi Scd, yes I'd welcome any advice. Being in my 50's and a car enthusiast and collector all my life I'm reasonably competent with 60's & 70's engines, however I'm near the end of my tether with this one. So, the story is.... Bought a series 2 XJ6 last October as a roadworthy vehicle and spent many winter evenings working on the car replacing anything that might possibly let me down. The car has covered 55.000 from new which is backed up by comprehensive history and three previous owners from new. The last owner passed away and I bought the car from his wife. He had owned the car for 20 years. It has never had, or needed a full restoration and I have 38 out of a possible 43 MOT certificates.

Generally the car is in good order, 55,000 miles with full history and extensive parts and service files.

When I bought the car it was running quite rough which was related to the AED. I managed to improve it's running by winding down the AED jet needle and subsequently fitting a manual choke conversion to the AED. The carbs are SU HIF 7 which don't have a manual choke option. I also replaced plugs, points, condenser, coil, distributor cap, rotor arm, HT leads, in line fuel filter, one in tank fuel pump, battery and checked primary wiring as best possible. At this point the car was running fairly well at what I'd say around 90%. Without specialist equipment this was as far as I could go so I sourced a guy who had Crypton tuning equipment. He spent around 1.5 hours on the car and it seemed to run well. He did mention the carb needles might need replacing but I'm not convinced on that. I took it out for a local drive and all seemed good. However, I subsequently discovered the engine missed quite noticeably above 2500 RPM which it didn't before. He said he'd retarded the timing so I decided to check this, however I can't move the distributor at all despite loosening the pinch clamp and clamp bolt. I do recall the sound of a hammer whislt he was working on the car so suspect he had a similar problem. This has led me to check and re-adjust just about everything and now the engine is running worse and misfiring. I suspect the AED / manual choke is still playing a part in this because the AED pipes to inlet manifold are remaining cold for quite some time, which means extra fuel is being provided even with the choke fully in. I have taken this apart and can't see anything obvious. The engine itself is in good order, runs quiet and doesn't burn oil. It might be the Crypton guy tuned the carbs relative to what was required with the AED still playing up and something has changed ? I appreciate many will say I should get him back, however he had travelled the best part of 200 miles so I can't see this happening, especially if I have to pay another 365 GBP. One thing I do appreciate is the plugs need to be cleaned in between messing around but this isn't making a difference. I hate to give up on things however I think my best bet is to have the car collected and taken to a garage such as Fraser suggested. This is around 30 miles from me so I would need to arrange a transporter as trying to drive an auto with these issues is a nightmare. That said I would of course be grateful for any advice !

Hi, apologies if I am going over what you have already done but I would have started with a compression check, looking for around 120 psi with no great variance between cylinders. Then onto ignition, the xj distributor is a bit of a pain to set up insitu, easier in my opinion to remove and set up on the bench, this will give you a chance to free up the pinch bolt , check and lube the mechanical advance and check the vacuum advance. Reset at 8 deg Static and look for 20 degrees plus advance at 2 k revs with the vac disconnected. Then you can start on the carbs! Firstly you need to get the AED switched off, I am unfamiliar with the manual conversion but assume there must be away of turning if off? Remove the carb dashpots and check the drop from the bridge top to the jet, think the factory quoted 3 mm at 20 deg, but this will give you an indication as to if they have been incorrectly adjusted. If the Crypton guy was trying to set the carbs with the AED still working he will have set it up far too weak.
Sounds like you were almost there before calling someone else in ! Dont give up too soon, unless there is something blindingly obvious a garage will just go through all the above checks and it sounds like you are more than competent of these yourself!
Good luck!

Hi Scd, many thanks for your advice. I did a compression test a few weeks ago and the numbers were fairly close. Can't be sure but I seem to recall they were all around 140-150 psi. I will carry out another test. Blanked off the AED this morning and had another look at things. Decided to change the points again but this made no difference, still mis-firing. I think the timing is reasonably ok, there's no run on or pinking and the car starts fairly well when warm condsidering the mis-fire and the timing marks are reasonably close with the strobe. Still can't shift the distributor even with gentle persuasion from a pry bar. The clamp moves easy enough but that's about it

What I have discovered is no spark on cylinder 2. Changed the HT lead, still no spark, tried two more leads and still the same.. Changed the distributor cap and rotor arm with no improvement. Checked other cylinders and they all have a spark, probably not brilliant but sufficient to run the engine on 5 cylinders and just about tick over in park / neutral. Fitted a new Lucas coil not so long ago which might be faulty, but I can't understand why it would fail on just one cylinder. I used the same plug to test all leads so it's not the plug at fault

Hi, you need to get that distributor out! There is a bolt (7/16 af socket) that holds the clamp assembly which the pinch bolt is part of with this removed it will come out but might need a bit of gentle persuasion, the alloy distributor body may have ‘welded’ itself to the cast iron block. It sounds like a distributor shaft that is not true and on no 2 cylinder the rotor arm is sufficiently out of alignment to not fire that lead, have a look inside the distributor cap and see if all contact points are the same. With the distributor out you will soon see or feel if the shaft is bent. Happy hunting , but sounds like you are getting there! Regards Simon

Hi Simon, that seems to make sense. I'm wondering if the hammering I heard resulted in damage to the shaft causing misfire at higher revs that didn't exist before. Because of this new misfire, and the Crypton guy telling me he'd adjusted the timing this led me to check the timing myself and I might have caused further damage trying to turn the distrbutor as well. In hindsight I can't imagine he actually managed to adjust timing as the distributor really is stuck solid. It might be stuck through alloy / steel corrosion however I have a reciept on file from the previous owner around ten years ago showing the unit was re-built by Distributor Doctor, a well known specialist in the UK and that doesn't seem long enough to seize as the car was kept under cover plus the alloy clamp is clean and easily moveable and the distributor body is clean as well. If the distributor body isn't 'welded' to the steel it begs the question why won't it move? I'll post how I get on !

Hi, try twisting the distributor, it may be that somebody put it back in with some jointing compound. Fortunately it can only go back in one way as the drive is slightly offset but not a bad thing to put the engine to 8 deg btdc which will make doing the static timing a bit easier when it goes back in. Again, good luck!

Hi Simon,

You were absolutely right regards the shaft running out of true, plus serious corrosion between the alloy and steel. Removing the distributor was a nightmare and I've just posted how I done this. I'm now taking the opportunity to fit a 123 distributor and hope the old girl we be up and running again soon. Many thanks for your sound advice on this.