Castor shims

[ashcloud]

Hi Alec
I checked on the universaL joint and it does have a very small play when pulled hard. I have heard about shaft balancing but technically I do agree with You, the at such a small diameter it is hard to get a serious imbalance but rather in the joint when it has room to move into an excentric position. What would they do to balance it, file some material off? They painted the shaft on the outside which in itself can create more imbalance then a shaft produced on a lathe. BUT maybe I am wrong?
Now my exhaust is on and tight and the driving is a little better again since there was obviously also an added noise to all the others produced but such old cars. I really enjoyed running up and down the road and I am very pleased about the tracking. At 110MPH I let go of the steeringwheel and it just stayed straight, WOW I love that part.
The engine is getting closer to where I want it and the preignition is at a temporary curve close to the original LUCAS (at 3400RPM a total of 45 degrees .... but it works). In a few weeks when the weather is better I will start a series of test drived to optimize the curve with a friend on the passenger seat working the laptop to reprogramm the ignition during driving, to see the changes under load.
Bernhard

[piman]

Hello Bernhard,

propellor shaft balancing is done by welding small pieces of thin sheet steel to the tube.
My theory, and it seems to work in practice, is that the cups and rollers are very precise so will be equal in weight, and the central spider is both light and small in diameter so is unlikely to be significant? That is why I try and ensure the flange is aligned to the same orientation to the shaft before and after to minimise any variation. (That said, it's possible, likely even, that someone before has rotated it 180 degrees when fitting a new joint)

I have no experience of this but I quote from Des Hammill's book (How to power tune XK engines).

"In no circumstances exceed 44 degrees advance on an XK engine".
Now you are only one degree over but worth remembering that high speed pre ignition is undetectable and better to be safe than sorry, especially as you are fortunate enough to legally run your car far in excess of our limit in the U.K.

Alec

[ashcloud]

Hi Alec
Is there a marking on the shaft (I believe I had seen something in the book, have to check on that) cause this is easily possible with people who fix a SS exhaust with furniture screws into the rubber.
The ignition timing is somewhat controversial since I also have D. Hamills book and also his ignition book where he constantly refers to the XK engine starting at no less then 34 and go up from there BUT here is something different:
the Lucas dizzy has a 19 Marking stamped into the baseplate and also the Jag Maint book has 19 degrees (distributor not carnkshaft) at 3400RPM that ends up 38 (19x2) + 7 static for the paperfilter element is a total of 45 degree. Now this factory preignition setting should even be good for Granny and the guy with trailer from Holland
Please correct me if I am wrong here.
Thanks Bernhard

[Martec]

Hi Bernhard,

Did I read correctly that your friend will set the advance with a laptop? So do you have a mapable ECU?

I've just plugged mine in and looked at my maps that I run on, and at full throttle it will only reach 32 degrees, and 40 on the overrun, all starting at 5-6 degrees............for petrol.

Mine has a standard 3.8 engine on 1 3/4" SU's, I would be very interested in your map. I'm running a map of revs against Manifold vacuum from the inlet manifold itself (not the front carb).

Good luck with your mapping.

Brian

[ashcloud]

Brian,
my engine and carbs are like Yours. I will be happy to discuss this (my favourite topic) but I think we should open an ignition thread for that.
I do have the 123tune ignition and I have been fiddling a lot with it, but now the time has come for more serious testing.
I do have to leave tonight for NYC but will be back on the 3rd. I will keep reading the thread but on my iphone it is a pain to answer.
I will lay down all the good and bad sides that I have had so far and we can exchange our experience with it (maybe we can improve matters this way)
Looking forward,
Bernhard

[piman]

Hello Bernhard,

you are quite correct, and I have just checked a handy little book that I have that gives Lucas distributor specifications and all three different types of distributor fitted over the years to the 3.8 model have 19 degrees maximum as the mechanical advance.

Alec

[ashcloud]

Greetings from sunny but cold NYC
Lets keep exchanging experience with the different
Settings in our electronic dizzies, OK,
Because everybody that I know is running the
wrong settings (too low) I even found an XJ6
Dizzy in my car (13 degree baseplate) which means
12 degrees off!!!!!! It still ran.
At my tuning shop they refused to go beyond 26 degree total!!!
Comment: to stay on the safe side, I cancelled.
D. Hamill says the semihemispherical burning chambers
do need these high settings due to there flamefront patterns.
Most people make the mistake of adding the vacuum setting to it
And that scares them, but the vac and the max preignition
happen at different times so they usually do not interfere.
Greetings Bernhard

[piman]

Hello Bernhard,

the Jaguar figures are quite high, my Triumph in comparison runs 30 to 32 degrees total advance, and the DB5 I had (A better comparison as the chambers are the same) was also about 32 from memory? The Aston manual specified setting the timing at maximum advance rather than idle by the way.
Yes, as the vacuum advance typically only works at between 2 to 3000 rpm when the manual advance has some way to go.

Alec

[ecosselynx]

Hi Guy's

While I don't mean to be a spoil-sport. Maybe you want to think about starting another thread on ignitions or such and leave this thread for the front end set-up. I'm interested in both and have followed the thread up until now, also hope to do so later on both points.
It will after all make it easier for people later on should they run a search!!!

Sorry, just thought you were drifting off topic.

[oldtimer]

That's right Ecosse Lynx, you tell them, naughty boys. before you know it we'll be at forty thousand feet!

Back to the Prop Shaft. The universal joint (or non-constant velocity joint) should have no perceptible play. With the shaft on the bench the rear flange will remain in any selected position but a worn joint will flop down.

The splined sliding joint should have between 0.002 thou - 0.004 thou radial movement when measured free of grease.

There, I feel better for that, now I can go back to sleep.

Oldtimer

[Martec]

Hi Alec,

Sorry It was my post that has started this running off on the ignition tangent, Should we start another post in Modifications or will you lift the lot to modifications. I am very interested in what others have set their ignitions readings to.

Brian

[ecosselynx]

Hi

Sorry for the delay in getting back to you, just drove my Mk2 up from Dordogne to Jockland the last two days . Never had to change items before, but I'll find out and let you know.

I agree with you that the ignition is an interesting topic, just thought if anyone else was to search for ignition information, their unlikely to look under Suspension.

There you go, smack on the wrist all done. Please all keep on with these very informative subjects. The front set-up I changed on my car 14 years ago. While it's very stable I don't know if my dogs dangly bits are as big as Bernhards for a hands-off at 110MPH (not that were allowed up to that speed)!

[ashcloud]

Hi and good morning
No, even in Germany it is 60mph on normal roads. Now here are the
Instructions for my tests:
1) pick a nice road (maybe a bit downhill)
2) drive it along (uphill) to warm up the engine.
More important, check that there is no Radar around!
3) turn around and get your goggles on (my door seals are old)
4) now start to accelerate and once you reach the desired speed,
Hands in the air (like on a rollercoaster) and wave (here in Germany people will wave back at you)
They like old Jaggies and at that speed it sounds really good!
5) ENJOY

Warning! Do this at your own risk

[ashcloud]

Back home from freezing Dallas, TX.
I just started a new thread:

Ignition, Timing and electronic Distributors
in Electrics

so we can continue the ignition topic in the right place, and keep the suspension here.
Bernhard

[ecosselynx]

Hi Bernhard

Thanks for the instructions