ill inquire tomorrow from the usual suspects for a manual.
people read novels for relaxation, i read tech manuals haha.
ill spray some fluid around the butterfly linkages and see if theres a leak in there perhaps. the freeplay was minimal but you never know i guess.
appreciate you commentary this evening.
I think what you should try first is to screw in the mixture adjustment screw on the rear carb that seems lean. That way you push the jet down, that gives you a richer mixture. Do that until lifting the piston of the carb by 1-2mm (either with a screw driver or with the lifting pin) no longer causes the (warm) engine to stumble. Hopefully. Repeat for the front.
If lifting the pin causes the engine to speed up it is too rich and if it stumbles it is too lean. Slight speed up and back to the same speed is ideal.
Youāll need to constantly go forth and back until both carbs do the same work (listen with a hose to your ear or the balancerā¦) and idle speed somewhere between 600-650 per the HD8 factory setting or higher if you want.
At idle I donāt see fuel delivery itself as a problem. The ASC wouldnāt have anything to do with it unless itās leaking air of course.
You probably know all this but it sounds exactly like what I experienced with a lean carb recently.
Try ebay for the haynes. I got lucky and found one for under 10ā¬, it has all three series covered reasonably well.
That is good. As I said, focus on other things then, mixture first.
Chris!
Welcome to the jaguar bunch. I have had an E type for 10 years and a
78 XJ6 for 43 years , worked on both and when I sold the 69 E it was
working, and when I had the 78 in the auction, every thing worked.
I can help you with anything you need.
I would get an electronic ignition, and a fuel injection system to start with.
WalterOnce itās running, however roughly, have you tried disconnecting plug leads one at a time, to see which cylinders are misbehaving? Might narrow it down to one carb, or maybe distributor cap\ignition. Do you have access to the original points distributor? That reduces the whole setup to the simplest configuration for troubleshooting. Take the chamber off the carbs and ensure both jets are at similar levels below the bridge, they should be pretty even at about 2-3mm below. I canāt remember the specifics, but the manual says start with the jets flush with the bridge and then turn the mixture screw 2 1\2 or 3 1\2 turns down as a start point. Someone can chime in with the exact numbers, Iām sure. Donāt get tied up with the cam timing, thatās not far enough out ( if at all) to cause this issue IMO.
**
Have you actually absolutely verified ignition sequence, Chris - as Nick suggested in previous postsā¦?
Having disconnected plug leads to swap the dizzy; itās very easy to get the connections mixed up. Just copying the previous set-up is no safeguard, even with 'double checking - and with plugs crossfiring the engine will shake about in idle. The xk will run well enough at high revs, even with serious faultsā¦
And I cannot find any reference to a compression test - have you done itā¦?
Frank
xj6 85 Sov Europe (UK/NZ)
15-36-24 (the old rule was ā15 is too young, 36 too old, 24 just rightā, which made a lot more sense when the average age of the members was nearer 40 than 80). And anti-clockwise.
Thatās a cute one!
I remember it as groups of three: 153-624. I use rhythm to recall number sequences.
2 Ā½ is a starting point but if plugs 1 & 2 are lean (3 being fed from the balance drilling?) Iād argue the front is set up well and the rear needs to be fatter. Depending on condition 2 Ā½ is barely getting close.
Maybe theyāre not lean but not firing and the two plug leads need to be swapped - but if itās been looked over 5 times it will have to be alright.
lots of good advice has been provided
I can add;
You need the Factory Service Manual for these cars, ( any car).
It used to be you could get a cheap CD ROM on Ebay for a few $,
but there is a used paper one on Oz Ebay atm for $60
If its a S2 with HD8, that is not original,
S1 XJ6 HD8 have diaphragms
I presume you have the cylindrical S1 ASC, not the rectangular S2 AED as a starting carb ?
Either must be fully operational or your car will be very hard to start, and run like a dog until fully warmed up (and I live north of Sydney).
If it starts easy without the ASC, its tuned way rich
I agree with other who have stated you must be systematic
(this car is new to you, and has been altered. You cannot assume some PO has not messed up)
which would involve;
triple check your plug wiring order, and that each plug is firing by pulling leads one at
a time
apply a vacuum gauge to your engine, a very good tool for poorly running engines
remove cam covers and verify timing with cam tool ($30 on Ebay)
you have already checked cam lobe clearances, so maybe you did the above as well ?
verify static timing, points gap, distributor is oriented correctly, verify engine timing at 3000RPM with timing light.
If all that checks out its time to systematically diagnose the fuel system
The HD8 is pretty simple, but needs to be taken apart, and a few things checked
do the jets move up and down when tuned ?..is fuel visible about 2mm down in each jet well, do the butterfly spindles move at all in the bush ? etc
imo, you must have an operational Starting Carb,
fix known faults first
My XJC did not run right for years after I replaced the Stromberg carburetors with HIF7. Until I discovered that both pot springs and jet needles had been messed with by a careless PO and were not suitable. Took me a while to figure out the right needles: transformed the car.
Eric makes a good point.
As far as I am aware, the correct Carbs for an Oz spec S2 are HS8.
I think they also had Strombergs. If I am wrong, please correct me
They have different Jet (and hence needle sizes) from HD8 from memory 0.90" HS8 vs 0.100" HD8
The needles can be removed and the code read on the needle shoulder using a magnifying glass and compared to a chart
HS8 are superior imo in that they can be more easily modified to manual choke
The S2 AED was very troublesome, but no one would ever remove HS8 and replace them with (XJ) HD8, so you must have had Stombergsā¦who knows ?
your mixture adjustment process is pretty much spot on how ive been approaching it. read that method from the above mentioned SU site and after fiddling on prior attempts (pre carby rebuilds) i thought i had it right. yet it would still backfire through the carbies and play funny buggers.
my old mans got a vacuum gauge tucked away in storage. the unit would be older then i am, but a bloody handy tool to get my hands on.
Random thought, i wonder if the ignition coil is breaking down under load at the higher/mild load rpmā¦ its a new component that had been installed onto the car (presumably when the points and things got done) but again i have no knowledge of its health.
i might swap that out for one of my older working datsun coils and see if that makes any change.
evil three, timing, fuelling and spark. either theyre 2/3 working or small issues on all fronts.
sorry everyone i had to wait for the forum to allow me to continue to comment, being new i maxed out the 20 responses already.
ill answer all the above comments and add additional info i worked out today.
Hi walter, thanks for the welcome.
i have swapped the points dizzy over to a s3 electronic dizzy already and i have been looking at efi as a project later down the track. found an efi intake from a wrecker s3 but you think i could remove the manifold, it was frozen in spot. had to walk away before i broke it off.
hi kevin, yes ive tried removing leads as the engines running to determine what pot wasnt firing. i initially did this when i had the points dizzy on as that dizzy had excessive shaft play and was deemed to be a fault to begin with. since changing to the s3 electric dizzy allot of those issues went away.
as for the carb tuning and jetting i have followed the SU websites handbook to the letter and had set up the carbs with a vernier confirming depth. i have since actually repeatedly gone back over and making fine adjustments to get the idle right. rev up etc.
hi frank, yes i believe i have it all correct, albeit the web is full of bum steer information. i had initially presumed the front cylinder closest to the rad was cyl 1 but then learn the jags had cyl 1 at the firewall. after mucking around i found the correct resources and rotated the dizzy and eventually got everything lined up where it needs to be fore correct sequence.
what i found on the original points dizzy was someone had rotated the housing within the clamp and had the sequence wrong that initally put me on the wrong path.
s3 electric dizzy was near plug and play and has been a good upgrade.
as for compression test yes i performed it when i first got it. 5 cylinders ranged at 140 -145 psi, and 1 at 115 dry, 140 wet. after some time and warming the engine up, that cyl came back up to a solid 140.
my old man and myself have tested it all again not long ago and all 6 are staying between 140-145.
frank thats the jingle i read once on the forum and i told my old man that, it made him laugh.
but indeed thats how the dizzy and leads are set
i did find that 2.5 turns was lean, more like 3.5 - 4 turns was where its come happy. but ive chase this for a while now.
tony, i tend to agree with you. i would love to source a FSM for the old girl. i have a collection of old datsun and nissan FSMs for all the previous cars i have. as mentioned earlier i read service manuals like people read novels. something about the technicality i enjoy.
as for the hd8, yes they had installed the cylindrical ASC. i have removed it for now as it wasnt in working order and would leak. ive lathed a bushing that goes where the bridge would join the base of the front su and also blocked off the distribution tube to the runners. ill eventually get around to replacing it with parts from SU, or Midel if they have anything,
it does cough and take a moment to come up and āsettleā at idle when cold, so i would be confident in saying its not overly rich. ive been partially holding the throttle down to get it kicked in the guts and then hold it when it warms up.
vac gauge is something ill invest in. will come in handy. not sure i have any my gauges left from previous vehicles.
i checked stating timing again today, dash over 8 degrees. no points as its electric s3 dizzy. the original points dizzy was well flogged out. extreme shaft movement etc. was something i changed early on as diagnosed issues with it.
would love to double check timing at 3000rpm, but it coughs and starts backfiring through the carbs at 2500, hence where all these thread has began.