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Polarity change

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[ QUOTE ]
Solbacken yes, https://www.starautoelectric.com

There are other instructions written by other people in other sites, but they all say to cause a short at the F and B terminals at the generator, and that is not the correct procedure. The Polarity of the generator must be changed at the Voltage Regulator, nowhere else. It was actually very simple.


[/ QUOTE ]---- /ubbthreads/images/graemlins/savewave.gif---Absolutely untrue! /ubbthreads/images/graemlins/nonod.gif---Keoke- /ubbthreads/images/graemlins/yesnod.gif /ubbthreads/images/graemlins/yesnod.gif /ubbthreads/images/graemlins/yesnod.gif
 
Hello Exotexs,

with regard to the particular MK 2 I own the fuel pump has a diode, which is polarity sensitive. I can swap it but I see no reason to.
I am aware of the possible confusion, but my wife is a rare female that understands such technicalities so I am happy with it as it is.

Alec
 
Well Piman, even if you forget to swap the diode it will just burn a hole in the cap and the points will get knackered sometime later.However, When our friend Exotexs reverses that "electronic fuel pump"; is he going to get a big surprise.---Keoke /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/yesnod.gif /ubbthreads/images/graemlins/yesnod.gif
 
I did not have to reverse the fuel pumps, only the Coil and the Ammeter wiring, re-polarize the Generator and buy a new battery, which it needed anyway. The procedure is reversible if I ever wanted to go back to Positive ground, but why would I? What I do want is to get one of those georgeous "fluted" Daimler Grilles for my '65 S type! I wonder if it would fit and if I can use the S type's grille bar and badge? you may say I'm a dreamer... /ubbthreads/images/graemlins/confused.gif
 
Hello Exotexs,

possibly the Daimler 250 grille will fit?, I don't know how much reworking jaguar did to the original MK 2 front panel.
With regard to S.U. fuel pumps some Jaguars had diode supression others had capacitor supression, the latter of course are not polarity sensitive.

Alec
 
hello Piman: well see, this is starting to get too complicated...Diodes, Capacitors, one has to be a rocket scientist to understand all these things, and I am not. I'm going to check on the Daimler grille, that's something I understand!

my concern now is a fuel leak at the carbs which has been annoying me for a while; yesterday I found the source of the leaks: the two reddish-fiber washers at both the "banjo" fittings of the fuel-line connections attaching to the fuel floats, and the plastic washer at the fuel float overflow-line bolted on top of the fuel float. I decided to clean the "spiral-shaped" fuel line filters (the ones with a copper or brass spring spiraling over the coned-shaped mesh) while I have everything disconnected and I get new sealing washers tomorrow: I noticed that the end of each spring is bent towards the center of the filter mesh; in my non-expert opinion, this bend of the spring would slightly obstruct the flow of fuel; ?? Or is that the way it should be? Should the end of the springs end in a normal rounded manner? thanks for any tips if you know anything about this. /ubbthreads/images/graemlins/confused.gif
 
Hello Exotexs,

yes, the banjo fibre washers go hard after many years and do not seal well. You should, in normal circumstances not see any fuel leaks from the overflow banjo. Now this has a strange arrangement of a washer which has three scallops on it's internal bore and a plain washer that goes under the bolt head. If the lower washer has had a plain one fitted at some time then there is a chance that the float bowl will pressurise and cause flooding.
The spring you describe sounds OK to me, I wouldn't worry about it, I assume it's shape is so the mesh filter can't fall out.

Alec
 
hello Piman, thanks for the help and clarifying; I replaced all 6 fiber seals today, 2 of which are scalloped, and yes, the top washer is aluminum while the scalloped seems to be of some plastic material. I went ahead and replaced the bowl-lid seals too. I brought the spring and mesh filter to my local shop and it doesn't seem to matter as you say, however, the springs and mesh filter are crimped together in mine, they are not separate parts, but yes, the "bend" at the end of the spring prevents the filter mesh from falling out forward. Seems to be dry now, had it running until engine got hot.

And of course, that brings me to the "dieseling" that happens when I shut the engine off. It wants to keep running, I've checked and double checked and triple checked all Vacuum connections everywhere, but it keeps doing it. Must be the timing I suppose, otherwise air is getting into the carbs after shutdown somehow causing the dieseling.
 
Hello Exotexs,

not a common problem with the XK engine, have you run the car much? If it has had lately a life of very short runs an 'Italian tune up' may be in order. If you are not familiar with this it is basically giving the car a good thrash with plenty of revs so as to burn off carbon deposits inside the engine. Just be sure, also, that the mixture is not too weak.

Alec
 
Responding to your dieseling problem. This can be affected by your timing being too early, some carbon buildup in the cylinders that slightly increase compression over standard (hence the Italian tune up that pieman recommends) or too low an octane for your gasoline. try switching too 91 or 92 octane and see if the problem is alleviated. Italian tune it. Maybe run some Marvel Mystery Oil through the intake manifold while running in the extreme case. The last resort is to back the timing off until you eliminate the dieseling. Hope aathis helps. Jack
 
Alec, Jack; thanks for these tips. it "diesels" off and on and always after it has warmed up, i.e., after it has gone through a number of warming-up cycles. Once in 5 times it shuts down fine like it should. very weird. I don't drive the S type everyday. yes, I use 93 octane. (the Manual says to use 98 octane, which is not available). Maybe it does need a good thrashing! the problem seems to come down to Mixture or Timing as you both pinpoint. I understand that this engine is not as smooth and refined as the 4.2 in my 1984 XJ-6, but this 3.8 engine delivers incredible performance at high rpm's, (at over 70 mph). I like it better than the 4.2. But the 4.2 is much smoother and stable at idling. At idling is where I'm having all the annoying symptoms with the 3.8, once it gets to speed, all symptoms disappear. By the way, it has the 9:1 compression, maybe that's part of the problem.
 
Hello Exotexs,

9:1, lucky guy, most are 8:1, but using a lower octane fuel could mean some re-timing is necessary or a higher octane if you can get it.

Alec
 
With 9:1 compression ratio, the octane is probably the culprit. Also you are comparing apples and oranges because the XJ6 is fuel injected and your 3.8 is carbureted. The fuel injected version is definitely smoother idling at lower RPMs. In addition to 9:1 compression, if you have a carbon deposit build up on the piston caps or head firing chamber the commpression will be further increased. Try running a good dose of Marvel Mystery (or similar additive) oil through your carburetors. The carbon buildup can be reduced and that will make a difference. Also ethanol in the gasoline can increase the octane. If you have access to "gasohol" it might help. I have used ethanol based gasohol in older engines with no consequences to valve seats, etc., as alledged by the oil companies. If this produces no results, then back the timing down a couple of degrees (retard).
 
[ QUOTE ]
yes, I use 93 octane. (the Manual says to use 98 octane, which is not available).

[/ QUOTE ]
There are three fuel octane rating/measuring systems in common use. The Motor Octane Number (MON), the Research Octane Number (RON) & the Pump Octane Number. The pump octane number as used in the USA is the average of the two ratings. Eg. (RON + MON) divided by two. European countries use the RON rating.

The "translation" between USA & Euro octane ratings:

USA = 87---Euro = 91---RON = 91---MON = 82.5---R+M/2 = 86.75
USA = 89---Euro = 95---RON = 95---MON = 85----R+M/2 = 90
USA = 93---Euro = 98---RON = 98---MON = 88----R+M/2 = 93

As you can see, the 98 rating in your manual is likeky Euro, & is equivalent to the USA 93 rating.
D
 
ok gents, to answer all your comments: I guess I am lucky, that 3.8 engine does produce some power, so much it doesn't want to shut down sometimes! Dumb question: Where do I add the Marvel oil to the carbs? to the fuel tanks mixed with fuel? Also, I like the idea of ethanol, I'm all for alternative fuels. Didn't the Germans have Hydrogen fuel already in W.W.2 ? I saw a pump the other day with a big warning saying "THIS IS NOT GASOLINE!", referring to Ethanol. I was tempted to try it but didn't, there was a line of people waiting to fill up with Ethanol, well, they must know something. I didn't know about the octane conversion, I take it that 93 octane in the US is the same as 98 octane in Europe then. I got the 98 number out of the Owner's Manual, dated 1964. so that eliminates my worry about not feeding enough octane to the thirsty 9:1 3.8.

Positive or Negative Earth: I suppose it doesn't matter as long as it has electricity, only a very few components are polarity-sensitive anyway. (I just learned that). I wanted consistency and decided for Neg. ground, it can be reversed if I ever wanted to go back to Pos. ground, but I don't think I will. What I will do is to put a Warning Plate near the battery that says: "The electronic system in this car is Negative ground".

Have you all seen Solbacken's engine? Three carbs, all polished parts. What a beautiful job!

Happy Thanksgiving Day to all of you! /ubbthreads/images/graemlins/savewave.gif
 
Exotexs, a very nice polarity warning plate for the car can be obtained from a LandRover dealer.---Fwiw---Keoke
 
The British SUs and ZSs are side draft carburetors and not as easy as a down draft to pour fluid into. However with a little more patience it can be done. Get an oil can trigger squirter or any other rig where you can pressurize an oil based liquid. Load the Mystery Oil in the device and give the throttle enough gas to raise the dash pot venturi and then squirt or blast away. The procedure will produce a lot of smoke but it will clean up deposits in the ignition chamber that might be raising the compression. If you have multiple carbs then you have to inject the Mystery Oil in each one for a complete treatment. It will have beneficial results.
 
[ QUOTE ]
Have you all seen Solbacken's engine? Three carbs, all polished parts. What a beautiful job!
Happy Thanksgiving Day to all of you! /ubbthreads/images/graemlins/savewave.gif

[/ QUOTE ]

I think you have mixed me and my very good friend Splanky. The car with the mirror-engine is his.
My S-type -66 is still under rebuilding and of course, Splanky has set the standard /ubbthreads/images/graemlins/crazy.gif.
https://photobucket.com/albums/c197/solbacken/?action=view&current=album_pic.jpg
 
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