Sorry Brian, I'm with Tangofox on this one. To illustrate, I'll give a hypothetical example.

The car is new. I think we can agree that the injection pump missing tooth will align with the dot when the crank is at Start Of Delivery for the #1 piston, yes? Someone then drives the car over the next 30 years for 300,000 miles. The chain has stretched. Because the chain has stretched, the missing spline no longer aligns with the dot on the pump case, it is a spline or two off and the injection pump is retarded accordingly and quite possibly out of the range of adjustment of the bolt slots in the case. A new owner decides to address some of the de-furred maintenance and checks the injection pump timing. Wow! It's off by 10°! The new owner then pulls the pump, places the crank at SOD for the #1, places the missing tooth on the dot and installs the injection pump back on the engine in the center of the adjustment slots. The injection pump is easily timed within the range of the slots.

There is no need for the new owner to install the pump with the missing tooth off the mark on the pump case when the crank is at SOD and if he/she does so, they may very well run out of adjustment within the slots before the timing spec is achieved. The proper IP timing is achieved when the splined pump sprocket is aligned properly with the pump case. Period. If a pump is installed using the method in the manual when the chain is new or when it is very old and stretched, the proper timing will be achievable within the slots.

The alignment between the coupling sleeve and the timing chain may be different by a spline or two, but the alignment of the missing spline on the injection pump will be aligned with the dot on the case.

wow.
you two are both arguing about different aspects of injector timing.

both of you are right, but looking at it from different directions.

1. it's totally true that IF the IP is installed to a motor with 15° of stretch but the crank is set to spec and the IP is dead on spec when installed the stretch will have no effect.

2. it's totally true that a stretched chain on a motor will affect an existing IP's timing. and if a new IP is installed by the teeth marks, on that chain, the timing will be off.

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No doubt. You cannot see what is happening to the IP alignment as the IP is being installed. But "Timing" the IP after installation will solve that problem. If the IP is without defect, the marks will be aligned at SOD, whether you can see them or not.

That said, the very real possibility of accidentally bumping the alignment during installation is a totally different concept that intentionally offsetting the alignment prior to installation.


No. Relocating the IP adjustment slots relative to the studs is what provides the additional adjustment range. If the IP were to be installed one tooth off, "timing" it properly would correct it back to "no teeth off."


When the IP is removed from the engine, one constant becomes a variable. When the adjustment range is "used up," that just means the alignment marks cannot be aligned with the IP installed, since the housing has "hit the stops." That issue is completely resolved when the IP is removed; then there is no impediment to aligning the marks.


The limiting factor is not the chain, it is the size of the adjusting slots on the IP. If the IP were infinitely adjustable, it could be adjusted to accomodate any reasonable degree of chain stretch.

Kindly explain why the bold portion of your claim is true. (It isn't.)

The IP markings are pertinent only to the internal operation of the IP. They are not affected by chain stretch any more than chain stretch causes the crankshaft angle markings to be in error.

Exactly. It occurs to me that perhaps there might be a misunderstanding of the IP drive configuration, especially with regard to the intermediate coupling. The intermediate coupling, combined with the adjustment slots, allows for infinite variability, completely eliminating any need for intentional misalignment in order to achieve the desired SOD/crankshaft relationship.

I believe I found the miscommunication thanks to Libby:

You both are referring to the missing spline on the IP being aligned with the dot on the pump case.

Is that correct?

From memory, I was referring to the missing spline being aligned with a feature on the timer. All of my references were in regard to rotating the IP spline with respect to the timer.

However, I now see that you were unconcerned with the position of the splines with respect to the timer and only referred to the missing spline as compared to the dot on the case.

If this is all correct, then I fully agree with you. Rotating the IP spline back to the reference on the block would return the IP to the middle of the adjustment range, independent of chain condition.

Time for a Group Hug....