Pump Timing???

[Justin]

I know that I have Posted on this before but after using the Guages to time the engine I am more Confused than Ever, I do not have a metric dial indicator but thats no big deal.

Let me get this straight, after setting everything to TDC What is the Reading that is desired for the Pump on the Dial indicator?

Roll the engine backwards until the dial indicator gets a steady reading,
then zero the guage, then put everything on TDC and get a reading of about 1.15 mm plus or minus .02 mm for the 1980 yellow dot pump, is this correct? or should I be setting it for a different setting?

Right now I have it set at 0.0425 inches which multiply by 2.54 cm/inch and then multiply by 10 mm/cm and you get 1.08 mm, which i think is retarded but my Previous setting was about 0.031 inches = 0.79 mm

the .031 inches started a lot easier, so please help guid me in the right direction

Thanks in advance
Justin

[Justin]

Thanks, so what is a good Happy medium?
The 0.79 was probably a little low then and I should probably shoot for about 0.90 to 0.95??

thats odd that the max should be 1.10 mm and the bently says 1.15mm, maybe i misread it

anyways thanks
Later
Justin

[Mark(The Miser)UK]

Justin which engine are you talking about? I see you own a 1.5 and a 1.6 N/A  which are timed to less are they not?

[chrissev]

Justin which engine are you talking about? I see you own a 1.5 and a 1.6 N/A  which are timed to less are they not?

it depends on what injectors you have in it.  If they are 55 bar time it to around .040 inches.  If they are 33 bar time it to .032 inches.  Timing it in metric is more accurate (if you have the luxury of having a metric gauge)

[Mark(The Miser)UK]

:mrgreen: Each 0.1mm you need is 4 thou (3.94 thou actually) so 40 thou for 1mm givesonly 0.6 of a thou error... :mrgreen:

[VWRacer]

Geez Mark, do you ever sleep? :wink:  :mrgreen:

[Justin]

Just for an update this is for a 1.5 L naturally aspirated diesel, and doing metric to standard conversion is not a problem, for every revolution on the dial indicator the shaft travels 1/10 of an inch, I forget how accurate it is, but its pretty accurate.

So with 130 bar injectors and being naturally aspirated, what would be a good timing mark to shoot for, (this is one of the old yellow dot pumps if that makes any difference)

Thanks for your help
Justin

[Northboundtrain]

Thanks, Justin for posting this question.  I just timed the new engine in the caddy to within the Bentley specs (I think it was 0.88 mm).  But I'd like to know more about the theory of timing.  How exactly timing affects performance, and how that is related to the injectors' bar setting.  I know that advancing the timing improves performance at the risk of too high exhaust temps, but I don't why.  I'd like to know more about what I'm doing if/when I decide to tweak the timing from the "stock" setting.

Anyone feel like giving a quick lecture on this subject?

[dieselweasel]

Relatively advanced timing equals higher cylinder temps and pressures, increased engine wear, lower boost, low exhaust temps, good fuel economy, and higher NoX emissions.

Relatively retarded timing equals higher boost, high exhaust temps, poor fuel economy, increased particulate emissions (black smoke), and high cylinder head temps.  

Advanced timing gives better performance since combustion is starting sooner relative to piston position.  There is therefore more pressure in the combustion chamber at TDC to drive the piston down.  

Not 100% sure about the relationship between timing and injector opening pressures.  I presume more advanced timing is required for injectors with higher opening pressures because a longer effective stroke of the plunger in the pump is needed to provide the pressure for opening the injectors.

As for engine wear with advanced timing, these engines don't seem to have any problems with a setting up to about 1.1 mm, which is the max advance for optimum performance.   On other engines, I have seen pistons crack with overly advanced timing.

[Northboundtrain]

Does the 1.1mm maximum apply to n/a engines as well?

[Justin]

I had my 1.5 at 1.08, and it ran about the same as 0.79 but it was a bear to start, So I started out setting it to 0.039 inches, which is 0.99 mm, still to much since it didnt start worth a hoot, so I moved it back to 0.95 mm, same thing, I finall moved it back to 0.035 inches which comes out to be 0.889 mm and it starts a lot easier, I might still move it back to .034 inches just for better starting, and we will see what kind of milage I get with it now

Hope this helps some one, and thank you for everyones help

Justin

[Northboundtrain]

I always thought that the cold start lever advanced the timing for easier starting.  Am I wrong?

[Justin]

From my understanding you are supposed to pull it out once the engine is started, the further advance should help warm it up quicker, but in cold weather more advanced timing = harder to START

[VWRacer]

Mine works as Justin describes. If I pull it out before cranking, the engine is harder to start.

[Deadeye]

Hey folks I'm new here.

The cold start device advances the timing to help starting.
But that was with a stock engine with the original pump timing.
Mine used to work great, when my dasher was fairly new.
but, after advancing the timing to where it is now, the cold start device has very little effect now.


Deadeye