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JX Boost pressure setting

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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 16 at 19:21
to be sure..

Max fuel position due to an internal unsprung cam of some description I guess.

However is this then the starting position for the lda rod end setting or the end max extended position? Sorry if blatantly obvious! Only thing I do know is the cam stop was in contact at full pressure as I put a dot of blue tack there to see what was going on.
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dave friday View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 16 at 21:42
Zeb this is from memory ,the accelerator lever is connected to (by a Spring )the plate1that the max fuel screw buts against ,the cam that the lda pushes ( when on boost)allows the plate1 to pulled by the Spring allowing more fuel.when off boost the return spring ( in the lda ) pulls the cam back pulling the plate1 back against the max fuel screw reducing the fuel.
I hope this makes sense.
Kr.
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 16 at 08:26
Thanks, I understand as I had to take the top of the pump off once to replace the throttle shaft bush. I'll have a look this evening hopefully.
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bootie3367 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bootie3367 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jun 16 at 18:16
Brian, been following this with interest. 
Ever since I changed the blue seal on the LDA shaft I have experienced a lot of smoke (black) on heavy acceleration, didn't before. The seal I changed had two washers on top of it, only supposed to be one yes?
I think I am getting more power when on boost as well.

Now I'm off to Scotland on Friday, driving the wife and dog back for the summer but I am flying back the following weekend due to new job.
I would like to pop over one weekend and take advantage of your know how on this subject.

Let me know.

Cheers
Jon
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jun 16 at 18:37
Hi Jon,if the " blue" seal was leaking a bit it could have affected the fuel pressure and the injection advance.
Re your visit; just give me a shout,
Ttfn,Barry.
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jun 16 at 20:28
Hi Jon, you must be joking, the sum total of my lda knowledge is in this post! I'm fishing myself hoping that someone had actually been through this before and could advise on the best sequence to setting up fuel and boost levels safely to get the best performance. All I can advise really is get EGT, boost and oil temp gauges before going the trial and error route or it will all go sour. An Oil cooler and intercooler or better still a charge cooler will help with Temps and power.

Hopefully at the end of this round of tinkering I'll be in a position to advise; I just hope it isn't advising you what not to do! 

Good luck with the move

Zeb


Edited by Zeb - 08 Jun 16 at 20:31
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 11:01
Hi Dave, removed the rod end from the cam to allow it to move freely when revved but it doesn't move? Even if I rotate the cam to any position it stays in the same place. Strangely the lda retracts a few millimetres so a vacuum is created when there is no load.

There must be some method to setting these things up somewhere?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 17:01
The cam inside the pump moves by 2 mm. !!
I had a look inside!!
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 19:07
Hi Dave, scratching my head again now then? When you said rev the engine you didn't mean rev the nuts off it did you? I actually removed the lda rod and connection plate, left the shaft and stop plate free to move, checked if moved freely by hand from stop to stop and then started the engine. Whilst moving the throttle lever by hand revved it a fair bit guessing 3000rpm max and no movement? I'll check again just in case I was having a "senior moment"..... 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 19:27
What I did ( with the lda shaft off and the engine off ) was to move the throttle to max a few times,the cam moved a little ( just off the stop )
I'm In the same boat as you ,trying to find out how to set the pump up.
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doc.g60 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doc.g60 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 20:26
This is a very interesting thread, I've been slowly trying to get my head round how this pump works. I have the same symptoms as Jon above since changing my lda seal, black smoke on load uphill or with foot flat but fine otherwise. It'll be great to see the results of all your tampering. Ive got a pump apart at the moment and will get some photos of how the lda cam / rod / lever operates in respect to the governor lever when I get a chance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 21:06
Hi doc, please do take some pictures just in case they help . As the pump is running well and there is no smoke under load visible to me I don't want to strip it down and create new problems.

Cheers 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doc.g60 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jun 16 at 23:12
I can't upload images to the forum yet but I've got some links.

This is the shaft that is controlled by the cam plate connected to the LDA


The cam profile of this shaft moves a small pin which in turn pushes a lever back and forth on the underside of the lid. You can see this in the next photos looking at the underside of the pump lid.

Here is the pin and lever with the LDA in resting position:


LDA extended retracts the pin:


This lever contacts the governor tension lever inside the pump the overall operation of which is too complicated to go into however the following image shows the things we are interested in. The fuel screw pivots the entire gov. tension lever assembly but the LDA pushes against the top of the gov. lever only.


(A caveat - I've only gathered this info from reading on the internet / opening this pump after snapping the top threads off my LDA shaft and have no real practical experience of tampering with any of this on a running van. There is loads of info on tuning the pumps with the LDA on top and in these cases adjusting the LDA seems to be the easiest method of increasing fuelling, but I couldn't find any info on the operation of the JX LDA and pump lid so wanted to get some photos out there.)

I'll let you get back to the real world testing now!

(-Post edited to correct operation of pin.)





Edited by doc.g60 - 11 Jun 16 at 09:01
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doc.g60 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 16 at 13:53
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 16 at 16:34
Great doc thanks. From that I understand what I need to for basic operation.

What I now need to understand is the lever movement relative to the shaft rotation angle. It would help to get a better look at the pin you snapped if you still have it? Looking at the pic you linked it may not be that sensitive compared to the top mounted space ship type?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doc.g60 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 16 at 08:52
You know what, I think I've got this backwards, I'll need to amend my previous post. Seems the pin retracts as the LDA operates. It must restrict the movement of the governor lever. Some more thinking required.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote doc.g60 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 16 at 09:37
In fact this makes more sense when you look at how the spaceship LDA works. They have a vertically operating shaft with a cone on the end which performs the same operation as our LDA shaft, moving a pin in and out horizontally. There are replacement pins being fabricated for these which have a more aggressive angle on the cone and change the operation, if you google Bosch VE pump tuning you can find discussion about it.

The shaft on JX pumps has 180 degrees of rotation between max and min, but the cam plate only rotates about 45 degrees, with very little adjustment on the wee max screw on the pump lid.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 22:45
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Zeb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zeb Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 16 at 08:29
Thanks Dave. At least it's easy to now tell the max fuel position of the pin and cam so I can check that. I have found a worn pump on club 80-90 a kind chap called Monty is willing to give away for tinkering purposes. Just need to pick it up from Chard which is an hour away from me.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave friday Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 16 at 09:34
The cats called Sausage and that's my mum in the 1933 Austin 7 with me driving.
I got a vacuum of .1 bar at 1600 rpm! So your right.
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