S195 Fuel Injection Timing Proceedures

[Henry W]

Here are a few pictures that may be helpful from two different owners manuals.  

It may be hard to accurately locate TDC by removing the injector IF the piston is dished or has a big tit sticking up in the middle of the piston. Such is the case with many direct injection engines.

If the piston has a flat top a dial indicator will work just fine in the injector opening in the head.   Check and see if the timing mark on the hopper alligns with the TDC mark on your flywheel.  Sometimes the factory marks are off a couple of degrees and you will only know this if you accurately locate TDC yourself.

Most singles have a timing mark scribed on the side of the hopper or radiator.  If you remove the radiator or hopper your timing mark is gone.



ANYTIME YOU HAVE THE HEAD REMOVED ACCURATELY LOCATE TDC and make new timing mark on the flywheel and a reference point and/or new pointer.

                                                    flywheel

Hello Flywheel,

What manual did you get the pictures out of. They look much better than the ones I copyed yesterday.

Henry

[flywheel]

The pictures are from my Changchai and Rufa brand engine manuals,
both more detailed than the Changfa manuals.
                                                                flywheel

[veggie]

Flywheel,

Thanks for posting the flywheel marking procedure. Very helpful.
My problem now is how do you find TDC? (without taking the head of) 

veggie

[veggie]

My S195ZN direct injection engine came with a "IDI" manual.
Does anyone know the injection timing for a "DI" 195 Changfa ?
Once I get that number, I can retard it by 2 or 3 degrees for slow speed operation.

veggie

[Henry W]

They sure are the best I have seen.

What I would like to see is a couple good manuals posted here and in white pages.

It would be a good Project to work on.

Henry

[Henry W]

My S195ZN direct injection engine came with a "IDI" manual.
Does anyone know the injection timing for a "DI" 195 Changfa ?
Once I get that number, I can retard it by 2 or 3 degrees for slow speed operation.

veggie

I need to find a ZS195 Manual also.

I guess for now you can always retard the timing until the engine is hard to start. (I think white smoke is a sign of a retarded engine but I am not a 100% sure) and then try bumping it up two deg and try it.

Bob, can you  help here.

Henry

[mobile_bob]

iirc the di engines are timed to the same spec as the idi engines,

for the project at hand i would go back to about 15 btdc and start there and see how it works out

according to engineering text

a typical diesel is timed to inject at 18 degree's btdc then there is the delay angle, and combustion
starts at 5 degree's btdc

if you back off to 15 degree's, and accounting for the same delay angle (that won't change anyway
with timeing as it is independent of timeing), then combustion should start at 2 degree's btdc

that should be just about right because the sharp pressure rise should just about coincide with the piston
being just after tdc instead of a few degree's before, where it will beat the living hell out of the big end brg,
the wrist pin/bushing and possibly crack or break the crankshaft.

there is also another concern i would have, that being the critical speed of the engine
critical speed is roughly defined as the specific rpm where the engine operates and exhibits
a dramatic increase in vibration. 

you don't want the engine to run anywhere close to the critical speed, and definitely run under load
at that speed or bad things "will" happen. broken crankshafts are common bad things.

anyone that has been a passenger on a ferry boat, and i assume any other large diesel powered boats
that use very large low speed diesels will remember what critical speed is, it is the rpm range at which
the engine as it is throttle up moving away from the dock that the whole boat vibrates violently and very harshly

the captain of the boat must increase rpm up past this rpm as quickly as possible and once past the critical speed
he can slow the acceleration to whatever rate he likes.

another application where many folks have witnessed it or can witness critical speed operation is down at the rail yard
when the engine is brought up from idle it goes through a critical speed that can clearly be felt through your feet
in some cases hundreds of feet away. its a really rough harsh vibration, but as with the boat captain the engineer
accelerates the rpm through the critical speed as quickly as possible, and should never pull a load at that speed.

in large ships the crankshafts are built to where one cylinder is spaced offset a few degree's to alter the critical speed of
the design, but with singles and twins this is not an option.

just something to be aware of when when working on re-engineering the changfa for 900rpm operation, i don't know what
the critical speed of your engine is, and even if i did, anything you attach to the engine will have effect on the specific rpm
where the critical speed will be. things like your choice of frame, driven components, etc all have some effect on critical speed

so basically even if we knew that a changfa di 195 had a critical speed of for instance 850rpm, the frame choice and drive components
might lower the critical speed by 50 or more rpm, or raise it by 50 or more.

i am sure there are tons of formula's to determine exactly what the critical speed might be, but it is probably quicker, easier and more
accurate to determine it by testing the final result.

if after all it ends up that 900rpm is going to be putting the engine under load at or near its critical speed, you will have no choice
but to either speed up or slow down a touch in my opinion.

bob g

[quinnf]

Yo Bob!

Every so often I learn something new from you.  I mean really new.  Something I've never heard about before.  Not that I know it all.  Far from it; it's just that you've worked around this technology for a long time while I've just been a tinkerer.

You mentioned the critical speed, which was something I have observed from time to time with engines and drivetrains, and thought I pretty well understood, but didn't know there was a name for the phenom.  So I googled it and came across this little gem, contemporaneous with Dr. Diesel himself:

http://books.google.com/books?id=2fRMAAAAMAAJ&pg=PA112&lpg=PA112&dq=diesel+engine+critical+speed&source=bl&ots=h01ieiA6N9&sig=pV73x5I3P0zVq-SZRwvc2KLR8f0&hl=en&ei=t3E6S5qvL4_asgPL5oTABA&sa=X&oi=book_result&ct=result&resnum=7&ved=0CCUQ6AEwBg#v=onepage&q=diesel%20engine%20critical%20speed&f=false

Copied it to my desktop, saved it as a .pdf and now I'm going to add it to Dr. Diesel's book that I also got from Google Books.

Thanks, Mon!

Quinn

[Edit:  Oh My Heck!  Here's another one!  This one is from Busch-Sulzer that Diesel was going head to head with back when the technology was on the cutting edge. 

http://books.google.com/books?id=FEV-AAAAIAAJ&printsec=frontcover&dq=diesel+engine&cd=9#v=onepage&q=&f=false

(Sorry for the interruption)

q.

[mobile_bob]

Quinn:

thanks for the kind words, it only seems fair to share a bit of my experience especially in light of the fact that i learn
so much from you and others on this forum.

figure if i try to put back as much as i can, as i take away from this forum in things i learn. maybe it will make for a better forum?

i want to thank you for the last book link, that one is cool
i gotta go find a hard copy!

did  you read about the "economizers"  pretty cool indeed, where the figure a total efficiency at something over 80% iirc

looks like there are some nice plates in that book as well.

sure would have been nice to have been able to tour some of those installations when they were in thier hayday!

bob g

[Henry W]

Bob and quinnf,

Thanks for sharing all the good stuff.

Bob I experianced the vibration on the ferry boats near Seattle years ago. I thought it was a prop that was out of ballance. But as the ferry speeded up the vibration dissipaired. I think I understand a little more why the manufactures post the operating speed range of an engine. It makes sense.

Quinnf that is some good reading material. I need to spend some time and read it.

Thanks guys,

Henry

[veggie]

Yep, when we go on the ferries in BC, the same phenomenon can experienced.
I will watch out for vibration that is uncharacteristic of the S195 engine.
Fortunately, for many pieces of equipment in use today, the critical frequency is well outside the operating range of the unit.
This is a design criteria in many products.

Bob, thanks for the comments on injection timing for slower running.

veggie

[veggie]

bob,

Is there any danger of retarding too far? What are the symptoms?
On a gasoline engine, the danger is burning an exhaust valve because of fuel still combusting when the exhaust valve opens.
Can diesels burn a valve if the timing is too late ?

veggie

[mobile_bob]

i suppose anything it possible, but on these engine's highly unlikely that there will be any damage
i would suspect at some point slower than 15deg btdc the engine might be harder to start, smoke more
or other issues such as dramatic loss of power, long before you risk burning a valve.

i have to keep reminding myself you plan on burning an alternate fuel as well, so you likely will have to tweak
the timing to suit the fuel and whatever rpm you settle on, balanced against, ease of starting and smoke and
expected power output.

your entering uncharted waters with this project in my area's, so as suggested i would start out conservatively and work slowly
making one change at a time, test and retest, tear down to inspect for signs of stress, followed by another slight change,
wash/rinse/repeat till you get to where you have a happy balance.

make sense?

i hope so, not sure some days if i make sense to myself



bob g

[vdubnut62]

I really wish this had come up when I had the head off the "Walla Walla Xing Dong"! I can't help it every time I think or say Xing Dong
that dadburn  old song about the witchdoctor runs through my head........ oo ee oo ah ah walla walla ding dong. HElp......!

Ok, I have a grip now!  All I have for a timing mark is a double hash on the flywheel and a STICKER!  yes, a gummy stick on sticker, with an arrow, on the hopper!
I really need a better system.
Ron

[rcavictim]

I really wish this had come up when I had the head off the "Walla Walla Xing Dong"! I can't help it every time I think or say Xing Dong
that dadburn  old song about the witchdoctor runs through my head........ oo ee oo ah ah walla walla ding dong. HElp......!

Ok, I have a grip now!  All I have for a timing mark is a double hash on the flywheel and a STICKER!  yes, a gummy stick on sticker, with an arrow, on the hopper!
I really need a better system.
Ron

Ron,

You really should remove that sticker and put it in a safe place so you can get it out whenever you need it!  Otherwise it could come off and get lost.  Then where would you be?