Guide Bushing 12HT (1 Viewer)

[PIPPI]

Hi all,
I'd like to have more fuel per boost; i have read some tread and, if I have understand I have to play with the guide busching on the i.p.
So if i'm not wrong I've to turn clockwise the wheel after remove the lock nut.
In order to be sure in the image, in the red circle, the nut that cover the screw I've to turn clockwise. The screw max load is the the other step... but first I would modify this to evaluate l'effect.
Thanks fon any suggestion and advice.

 

[PIPPI]

HI ,
I'have read the FSM. I'm completely wrong. TRhe nut is the accelerator damping. The regulation of the bushing is on the top.-.. solved.

 

[kevin in okinawa]

do you have an EGT guage set up? if not, you really should before you mess with the fuel and boost settings too much.

 

[relaxedcruiser]

Hi Pipi,
I know it has been a while since you started this thread...
In the meantime - I hope that you found out that the screw at the end of the boost compensator is actually for off-boost adjusting.
The guide bushing adjustment you were looking for is accessed from the top of the boost compensator and can only be reached when the boost compensator is unbolted or the inlet manifold has been removed. For that very reason I have done a handy modification:

12HT Boost Compensator Diaphragm - https://forum.ih8mud.com/threads/12ht-boost-compensator-diaphragm.1088726/

Hope this could be interesting for you or other tinkerers

 

[Zeepaard]

Hi Pipi,
I know it has been a while since you started this thread...
In the meantime - I hope that you found out that the screw at the end of the boost compensator is actually for off-boost adjusting.
The guide bushing adjustment you were looking for is accessed from the top of the boost compensator and can only be reached when the boost compensator is unbolted or the inlet manifold has been removed. For that very reason I have done a handy modification:

12HT Boost Compensator Diaphragm - https://forum.ih8mud.com/threads/12ht-boost-compensator-diaphragm.1088726/

Hope this could be interesting for you or other tinkerers

Hi,thank you for this link! I have made the same plug in the aneroid housing and my engine and pump are totally overhauled.Before that i had lots of power.smoke(blue-black) and other problems.
Ther is now absolute no smoke but also no EGT and powerThe pump is set to original specs.I am running an Wink Turbo with 1 bar.But to give it a bit more grunt i want to adjust star wheel and max fuel.But what is best to start with?max fuel or start wheel?What are yours experiences?

 

[relaxedcruiser]

I would alter the max fuel screw at the front first. .out means more fuel - start with a 1/4 revolution You can adjust it to your likings... I would just go as far as the exhaust gases stay clean. Personally I don't like visible black smoke under full load for aesthetic and social reasons. Also I don't want EGT rising too fast, but that's what they do if you dump heaps of fuel in the combustion. Your improved turbo / more boost may well help with burning that diesel clean.

The boost compensator is not allowing max fuel until boost is present, the star wheel regulates the preload of the spring which is supporting the diaphragm against the boost and as such is regulating the amount of max fuel is allowed in relation to boost.
Long story short - reducing the preload will give you max fuel earlier, higher preload max fuel later while reving up.

Having said that - when I got my pump back from a professionell Bosch / Denso / Keiki Shop it was the same.....no power, no grunt....and unlike before I gave them the pump to check the calibration - I was not able to up the fuel using the max boost screw. I could completely unscrew the max boost screw without any power gains. The normally trustworthy shop had wrongly altered the boost compensoator preload to a point where it was not anymore able to allow max fuel. Once I reduced the preload I was able again to adjust max fuel on the designated screw.

Keep a very good written record of what are you altering is my advise.

There is one very interesting thing here....a while ago I tried to get information from people here about flat out max EGT a stock 12HT would produce.
I believe that the engine designer / builders of the 12HT tuned it in a way that you could go up fast inclines flat out using all the power the engine can deliver without worrying about EGT. Let's say fourth gear 2600 rpm.. To know what they thought would be safe for the engine would be interesting.
Of course all the people, including me, are fitting EGT gauges after they start tinkering with the settings.
So my question obviously is how high are your EGT climbing going flat out long fast hills with the stock pump settings.
(If those hills are not to hard to find in your part of the Netherlands)

Got a bit carried away in my lunch break here.... looking forward to your reply

 

[Zeepaard]

Thank you for your extensive response! I will explain a little more about my experiences. To start with myself; I have a lot of experience with technology and diesel engines. But with my own 12HT I had a lot of problems due to errors during the first revision that I had outsourced 11 years ago. The result was increased oil consumption, which also caused a lot of wear on pistons and valves after 140,000 km. The fuel pump was also only tested when I had paid for revision.
Now we have taken on the overhaul ourselves and have outsourced drilling and grinding. Everything has been done and meets the factory values. The fuel pump has also been completely overhauled and is correct in terms of yield.
The engine has now run 2000 km and does not smoke and has no power.
I myself have the feeling that I have to look for it in the boost compensator. At a slight slope with 1400rpm in eg 3rd gear, there is no acceleration. Above that there is power.
But the max fuel is of course easy to regulate.
To get back to your question, max EGT has been 450c so far. It was always 650c before. AFR was 22;1 under load. Now I have yet to measure that.
I would like torque and power again but rather not too much smoke.
To be continued!

 

[relaxedcruiser]

Hi Zeepaard,
have you done more tuning yet, any luck with the max fuel screw or boost compensator settings ?
I'm just back from a 1700 km round trip up north here and just need to mention again what a great tourer especially a 12ht equipped 60 is - this combination of rugged driveline, mechanical straight six and comfort is just so good.
I wish that you can enjoy that again soon.

 

[Zeepaard]

Hi Zeepaard,
have you done more tuning yet, any luck with the max fuel screw or boost compensator settings ?
I'm just back from a 1700 km round trip up north here and just need to mention again what a great tourer especially a 12ht equipped 60 is - this combination of rugged driveline, mechanical straight six and comfort is just so good.
I wish that you can enjoy that again soon.

Hi Relaxecruiser, thank you for your interest! We are jealous of your beautiful country! That is different here, everything flat and diesels are banned by the regulations. We can enjoy a few more years, but it will not get any easier Coincidentally I did the last test tonight
Have an AFR meter in the exhaust and max fuel is now turned out 3/4 turn. I turned the Starwheel 8 clicks clockwise. Turbo pressure is 1.0 at 1800rpm exhaust temp runs to 500c but we have no mountains AFR was then 22.5:1 and above 2000rpm 24:1. Then my wife drove her Mini behind me and turned back the starwheel 1 click because there was smoke. Now it is 23.2:1 at 1500 rpm and light haze. it is a lively motor again! Great to be able to adjust the starwheel so easily.
The 12Ht is in an HJ45 with H55F gearbox and 3.7 diffs. Goes like the fire brigade and great technology. Hopefully next year to Morocco. Thanks and Kind regards
(what is a starting smoke limiter?)

 

[relaxedcruiser]

Hi Zeepaard,
I'm glad to hear that your engine is pulling better now.
I traveled a lot in Morocco some years ago, very good memories, very good pistes too !
I've send you an pm ...