The first thing I would like to do is thank all you fellow 1st gen addicts for all the wisdom you share on this site. I have learned a lot while lurking in the shadows! There is one thing I have never seen covered , and can find no one to answer. Timing is always referred to in degrees on this site. All the spec stuff is referenced as MM plunger travel at TDC. My truck came with paperwork stating timing advanced from 7-13*. I have the plunger travel gauge, and what I would like to know is how to convert plunger travel in MM to crankshaft degrees. Thanks much Jeff

 

First, WELCOME. I can't help you with the timing as most I think just grab the injector pump and give it a twist. I know there is more of a true science to do this and it is accurate, but I have not done that and I don't think anybody from VT would have the proper tools.

So, mostly just saying WELCOME. Glad your out from the shadows to give your helpful hints.

 

Thanks Nuttymopar. I suppose I could degree the balancer and figure it out that way. When I see people listing their advance in degrees, 15 seems to be most popular, they must have a way to know they are at 15. Such as 15* crankshaft = 1.5 mm plunger travel. If I knew what the MM reading for any given crankshaft timing was, and how much the plunger moved for every degree, it's all downhill from there. Hopefully one of the wizards out there has figured this out and will chime in on this. Thanks

 

In the 1.2 to 1.5mm range, and 12 to 15 degree range, .1mm corresponds to one degree of advance -- at least that seems to be the conventional wisdom. I have not found that explicitly stated in a manual anywhere.

 

It would entirely depend on the angle of the ramp, or cam, that the plunger rises on. I suppose somebody could figure this out if they had one available to look at. Pump rotates like the camshaft right? So it turns half as fast as the crankshaft. So for every 1* of crankshaft rotation, the pump turns .5*. So for a 2* differance in crankshaft to pump timing (15* to 17* = 1.5mm to 1.7mm) would mean a 1* rotation in the pump. Or .2mm travel for every 1* in pump motion. If the the profile on the pump plunger/roller/cam is flat, like ramps up and down, then there would be a 1:1 corilation, if they are rounded at all, like a cam, then the 1:1 relationship will only be true within a small amount of rotation. Perhaps the angle is flat within the range that we're talking about. Clear as mud? I think I'm confused now.

 

Bye the way Welcome

 

Tuckerdee, you are absolutely correct. I haven't taken the cam out of a pump yet, though.

 

Tuckerdee, That all makes good sense. It also jives with what Alec said about 1*=.1mm. You referenced 15 and 17* corresonding to 1.5 and 1.7 mm. Do you know that 1.5 = 15* or was that just used as an example? I want to use a pulse adapter to time these things with a timing light, but need to have a baseline to start with that I know is accurate in crank degrees. There is some loss between the pulse and the flash, and a known baseline is needed to know what you are losing. So what I still need, is to know if 1.5=15*, 1.4=14* etc. or what the exact relationship is. Thanks for your thoughts. Jeff

 

I don't have specific experience doing it, nor have I tested the relationship to 1*=1.5mm. It just seems to be generally accepted knowledge on this forum. If someone went to the trouble of finding TDC the way WannaDiesel describes, and then timing the pump correctly with a dial indicator, I suppose it would be easy enough to figure it out. I guess my questions would be: Is 15* the point where the plunger STARTS to rise? Or does the 15* correspond to the point where the injector pops open?

 

I talked to the mechanic in OR. that timed my engine from 7-13* and asked him how he knew. They use a pulse adapter and light, and figured out a long time ago how much loss was in his adapter, and they just find TDC and go from there. In answer to your ?, the 15* would be when the injector pops or very close to it because the piezo clamp on the line has to sense the pulse which would be from the injector popping. Finding TDC and using the gauge is all neccesary as well as degreeing the first balancer to know what is what with the light. But due to the losses in the adapter system, and each one will be different, a known baseline is still needed. Timing with the gauge to 1.5mm still doesn't provide a known crank degree to figure out the losses in the pulse adsapter with.

 

I see. So maybe, instead of saying "We think that 15* of timing = something like 1.5mm of travel," it's more accurate to say the opposite of "We think that 1.5mm of travel = something like 15* of timing." It's all about the symantics.

Flyzlo, I just noticed that you're from ND. Where abouts? I spent a year working about 40 miles north of Bismark. I used to call it The Land of the Frozen Chosen. Brrrrr!!

I did a carfax look-up on my truck before I bought and it actually came from ND as well. And when I was installing a 5ver hitch in it I ran across an original key and key ring from the dealer in (now I forget) either Minot or Williston. Crazy!

 

There is a difference between static timing and the piezo sensor timing -- which I will call dynamic timing for lack of a better phrase, and at the risk of being confusing.

The spec calls for you to set the timing statically, by measuring plunger lift at TDC.

When you use the piezo sensor, you are measuring when the injector pops.

These two methods are quite different: the static method excludes the time it takes for the fuel pulse to build and then travel down the injector line (which is different, in terms of crank degrees, depending on the engine speed). It also excludes the effects of the variable timing mechanism.

So, if I understand the scenario correctly, you couldn't calibrate your piezo sender by measuring the static timing, becasue you don't know how much to adjust for the hysteresis in the pulse, the latency in the injector line, or the effect of the variable timing advance? Or am I mis-understanding what you are trying to do?

 

First, Tuckerdee, I live in Minot. Alec, Thats' pretty close with the exception of the variable timing. Don't figure that to be an issue at idle. What I'm after is not complicated. If I know that any given plunger lift in mm. equals a corresponding crankshaft degree, I can figure the rest out . I need to static time one engine myself, so I know it is right, but need to know what crankshaft degrees equal whatever I set the plunger lift to, so I can check it with the light to see how far off the light is for future use.