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  #16  
Old 11-23-2012, 03:19 PM
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Quote:
Originally Posted by qwerty View Post
A-B lights use a reference point at 15 ATDC which corresponds to an actual start-of-delivery at 24 BTDC.

No, it doesn't. The one drop per second just occurs at 9 degrees early.

See, I can also confuse the forum and post irrelevant info for no good reason.
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  #17  
Old 11-23-2012, 11:48 PM
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Quote:
Originally Posted by Brian Carlton View Post
No, it doesn't. The one drop per second just occurs at 9 degrees early.
Not according to Bosch, it doesn't. Start-of-delivery and start-of-injection are not the same concept.


Quote:
Originally Posted by Brian Carlton View Post

See, I can also confuse the forum and post irrelevant info for no good reason.
If you choose to use the term "timing," I would submit that you need to specifty the specific event being described. In the absence of any qualification, I suspect that the typical reader would infer that you are referencing start-of-delivery.
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  #18  
Old 11-24-2012, 01:40 PM
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Originally Posted by qwerty View Post



If you choose to use the term "timing," I would submit that you need to specifty the specific event being described. In the absence of any qualification, I suspect that the typical reader would infer that you are referencing start-of-delivery.
I only need to qualify it if you're choosing to parse definitions for no good reason. I'm really not interested in that.

For most on the forum, we're simply trying to compare three different techniques available for setting timing. The fact that one of them measures the start of delivery, one of them is just a comparable standard, and one of them is the actual injection event is not meaningful in the discussion..........but, you already knew that and decided to waste space on here.
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  #19  
Old 11-24-2012, 07:28 PM
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Originally Posted by vstech View Post
oh, I think I see. the a-b light measures to the ATDC setting, which lines up perfectly with the pulse of BTDC... I get it.
The fact that both occur at 15 degrees from TDC (albeit on opposite sides) is pure coincidence. There is nothing "perfect" about it.
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  #20  
Old 11-24-2012, 09:08 PM
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Originally Posted by Army View Post
I'm interested to hear if you've got a reference for the difference between the start of delivery and the point of delivery when the injector lets go; at engine revolutions below the interaction of the timing device.

I've been trying to find one for ages.
You and I have spoken on this exact subject in the past and the information was provided to you at that time.

Either you have forgotten it or dismissed it..........
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  #21  
Old 11-25-2012, 03:31 AM
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Quote:
Originally Posted by Brian Carlton View Post
You and I have spoken on this exact subject in the past and the information was provided to you at that time.

Either you have forgotten it or dismissed it..........
Well I must have forgotten - sorry about that - can you send a friendly reminder?

EDIT:-

You had me looking through my PM box Brian!

In a reply to a PM that I sent to you asking for information, you said that you'd compared the use of the A-B timing lights and then set up a system that used a sensor on an injector line etc and that the result of that system gave a result of 15 degrees BTDC.

I guess this is the information you mean? (This means I'm checking to see that there wasn't something else sent that I have missed)

I really do appreciate real world results - and I do value measurements more than theory most of the time!

But nevertheless I still am at a loss to understand why the FSM would talk about "dynamic timing" and even go so far as to include another section describing how to set up the position of the tachometer probe on the front of the OM617 so that that too can be used in the process of "dynamic timing"; and yet not supply the basic data that says it should happen at XX degrees BTDC at XXX rpm.

It has got to be written some where => that's what I want to find!
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Last edited by Stretch; 11-25-2012 at 03:56 AM. Reason: Found it!
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  #22  
Old 11-25-2012, 09:09 AM
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Quote:
Originally Posted by Army View Post

But nevertheless I still am at a loss to understand why the FSM would talk about "dynamic timing" and even go so far as to include another section describing how to set up the position of the tachometer probe on the front of the OM617 so that that too can be used in the process of "dynamic timing"; and yet not supply the basic data that says it should happen at XX degrees BTDC at XXX rpm.

It has got to be written some where => that's what I want to find!
At the time the vehicles were developed, I sincerely doubt that the equipment was available to economically measure a pressure pulse from one of the injection lines.

The M/B reference to dynamic timing is interesting, however, I don't believe they were referring to the type of system that uses a clamp to one of the injector lines.

If you can find it, I'd sure be interested to see it, but I don't have a lot of confidence in that. Remember that M/B developed the A-B light in 1984 to eliminate the problems with the drip timing approach. If they had another method, why bother?
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  #23  
Old 11-25-2012, 09:21 AM
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Quote:
Originally Posted by Brian Carlton View Post
At the time the vehicles were developed, I sincerely doubt that the equipment was available to economically measure a pressure pulse from one of the injection lines.

The M/B reference to dynamic timing is interesting, however, I don't believe they were referring to the type of system that uses a clamp to one of the injector lines.

If you can find it, I'd sure be interested to see it, but I don't have a lot of confidence in that. Remember that M/B developed the A-B light in 1984 to eliminate the problems with the drip timing approach. If they had another method, why bother?
Thanks for your response Brian. I spent a bit of time this morning combing my way through the FSM.

From what I can gather together there are two ways of using the A-B timing light method:- in the OM617 turbo part of the FSM there's the static way described in chapter 07 -111 and 07-116 => this is essentially turning the crank by hand until you get the desired position annotated by the A-B light box. But there's also chapter 07-108 where you do the begin of delivery check with the engine running...

...the method detailed in chapter 7-108 is what I guess has caused the confusion! (Well certainly my confusion!) This is a dynamic method but it is still using the A-B timing functionality and not a clamped on the injector line sensor.

I'm guessing that somewhere this information exists as the A-B light method is pretty much out of date - I can imagine that most diesel garages would be using sensors on injector lines... I'm going to see if the dealer will tell me! Perhaps there is something in WIS. If I find it I'll let you know.

(This kind of information isn't by any chance available for more modern engines is it?)
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  #24  
Old 11-25-2012, 09:31 AM
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Originally Posted by Army View Post

...the method detailed in chapter 7-108 is what I guess has caused the confusion! (Well certainly my confusion!) This is a dynamic method but it is still using the A-B timing functionality and not a clamped on the injector line sensor.

I'm guessing that somewhere this information exists as the A-B light method is pretty much out of date - I can imagine that most diesel garages would be using sensors on injector lines... I'm going to see if the dealer will tell me! Perhaps there is something in WIS. If I find it I'll let you know.

(This kind of information isn't by any chance available for more modern engines is it?)

I believe you're referring to the "RIV" method of checking IP timing. That method requires another piece of expensive equipment and I'm not real clear on exactly how it functions.

I'm fairly sure the A-B light has become the standard for any independent shop. It's very fast and relatively cheap. The only problem is for vehicles that were built before 1984. In reality, they are getting to be a very small fraction of the business of an independent (an non-existent for a dealer).
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  #25  
Old 11-25-2012, 12:48 PM
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Quote:
Originally Posted by Brian Carlton View Post
I believe you're referring to the "RIV" method of checking IP timing. That method requires another piece of expensive equipment and I'm not real clear on exactly how it functions.

I'm fairly sure the A-B light has become the standard for any independent shop. It's very fast and relatively cheap. The only problem is for vehicles that were built before 1984. In reality, they are getting to be a very small fraction of the business of an independent (an non-existent for a dealer).
Perhaps another dimension of confusion is that the FSM uses the term RIV in each of the titles of the three chapters to which I referred?

As far as I can make out the additional bit of expensive equipment is a glorified tachometer that also monitors the position of the IP. There is a section in chapter 07-010 going on about RIV which means "Reference Impulse Verification" apparently.

In all of these RIV tests they seem to depend upon the IP being set up correctly in the first place. Much like the lug on the front of the crankshaft {that is used by the tachometer} another lug is fitted to the IP governor. This box of tricks just calculates the "chronological distance between the two pulses" (see chapter 07 - 010 again). So it is possible, for example in the situation of wear or poor adjustment, for begin of delivery to be happening at a different time - no matter what them there lights of the box of tricks says.

A "point of release" measurement seems to me to be a more desirable method of measuring.
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  #26  
Old 11-25-2012, 09:58 PM
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Quote:
Originally Posted by Army View Post
Thanks for your response Brian. I spent a bit of time this morning combing my way through the FSM.

From what I can gather together there are two ways of using the A-B timing light method:- in the OM617 turbo part of the FSM there's the static way described in chapter 07 -111 and 07-116 => this is essentially turning the crank by hand until you get the desired position annotated by the A-B light box. But there's also chapter 07-108 where you do the begin of delivery check with the engine running...

...the method detailed in chapter 7-108 is what I guess has caused the confusion! (Well certainly my confusion!) This is a dynamic method but it is still using the A-B timing functionality and not a clamped on the injector line sensor.

I'm guessing that somewhere this information exists as the A-B light method is pretty much out of date - I can imagine that most diesel garages would be using sensors on injector lines... I'm going to see if the dealer will tell me! Perhaps there is something in WIS. If I find it I'll let you know.

(This kind of information isn't by any chance available for more modern engines is it?)
I can provide a bit if evidences supplied by a Member of another Forum. In the chart there is an Engine rpm and the timing specs at that rpm.
Attached Thumbnails
Setting start of delivery-dynamic-timing.jpg  
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Last edited by Diesel911; 11-25-2012 at 10:15 PM.
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  #27  
Old 11-25-2012, 10:11 PM
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Originally Posted by Army View Post
Perhaps another dimension of confusion is that the FSM uses the term RIV in each of the titles of the three chapters to which I referred?

As far as I can make out the additional bit of expensive equipment is a glorified tachometer that also monitors the position of the IP. There is a section in chapter 07-010 going on about RIV which means "Reference Impulse Verification" apparently.

In all of these RIV tests they seem to depend upon the IP being set up correctly in the first place. Much like the lug on the front of the crankshaft {that is used by the tachometer} another lug is fitted to the IP governor. This box of tricks just calculates the "chronological distance between the two pulses" (see chapter 07 - 010 again). So it is possible, for example in the situation of wear or poor adjustment, for begin of delivery to be happening at a different time - no matter what them there lights of the box of tricks says.

A "point of release" measurement seems to me to be a more desirable method of measuring.
Yes, the A&B Light, the RIV Method and the Timing Locking Pin all reference a projection on the Camshaft and assume the rest of the IP is timed correctly. There is no compensation for wear that would change the begin of Injection.

On the other Hand the Drip Method or any Impulse Method that clamps on to the Injection Hard Line only references the #1 Element.
It is sort of assumes that the Tappets, Rollers and Camshaft that move the other Elements are worn the same as the #1 and of course that may not be the case.

None of the Methods is perfect.

In the Manual you can check one of the other Elements to see if it drips the proper amount when it is supposed to. I am guessing you can only do one other Element because the degree markings do not go all the way around the Crank Damper. Otherwise it would be possible to check all of them.

Then there is the issue if #1 is OK and the others are not what do you do about it?
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  #28  
Old 11-26-2012, 04:32 AM
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Originally Posted by Diesel911 View Post
Yes, the A&B Light, the RIV Method and the Timing Locking Pin all reference a projection on the Camshaft and assume the rest of the IP is timed correctly. There is no compensation for wear that would change the begin of Injection.

On the other Hand the Drip Method or any Impulse Method that clamps on to the Injection Hard Line only references the #1 Element.
It is sort of assumes that the Tappets, Rollers and Camshaft that move the other Elements are worn the same as the #1 and of course that may not be the case.

None of the Methods is perfect.

In the Manual you can check one of the other Elements to see if it drips the proper amount when it is supposed to. I am guessing you can only do one other Element because the degree markings do not go all the way around the Crank Damper. Otherwise it would be possible to check all of them.

Then there is the issue if #1 is OK and the others are not what do you do about it?
Thanks for the "German" data you posted (in your post before) - it is interesting to see that chapter 07.1-114 in English does not include that information!

I haven't done each of the various tests detailed in the FSM (yet! - I think it would be an interesting exercise though) but there is mention of comparing the begin of delivery at #1 and #4 in one of the many chapters (that could have been in the OM616 manual - I'm suffering from information overload at the moment - I'll wait for it all to settle down in my head for a bit)...
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  #29  
Old 11-26-2012, 05:14 AM
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Yeah, yeah, I used to use acoustic timing on many of my old gasser cars. Loosen the distributor lock down bolt, turn the distributor until the engine sounded strong and lock it down.

Static timing on old VW's.

Timing lights are for sissies.
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  #30  
Old 11-27-2012, 11:49 PM
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Originally Posted by Codifex Maximus View Post
Yeah, yeah, I used to use acoustic timing on many of my old gasser cars. Loosen the distributor lock down bolt, turn the distributor until the engine sounded strong and lock it down.

Static timing on old VW's.

Timing lights are for sissies.
In the non-emission test days you could do it by Ear, rpms or use a Vacuum Gauge.

I still find the Timing Light handy as I check My Van before going for the Emission Test.

On another Vehicle at the Emission Test I was told My Timing was too advanced. However, since I had checked it with the Timing Light and knew that was not so.

What had happend is the Tech had used the Automatic Transmission Timing Spec and not the Manual Transmission Timing Spec.
So no more argument from the Tech and I passed.
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