ClassA4x4

My earlier post:

Rick 12v CTD

Did you ever do any more work on this and find out definitively where your timing is set?

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ClassA4x4

No, I haven't. I left the ksb disconnected. I concluded my timing is just right for what I want. I drove to Baja like that - 1400 miles - no issues, except my Fss died and had to do a field repair / replace. Luckily I had a new one in my boonies box.

Anyway when I connect the ksb, it lowers the idle by about 20rpm. Does that mean that my timing is beyond the reach of the ksb advance, iow, ksb is useless throughout entire rpm band?

BC847

Folks need to better understand how the KSB effects injection event timing.


- When the injection event timing is advanced, we are injecting the fuel earlier in relation to the piston on the compression/power stroke. In addition to other effects, with injecting the fuel earlier, there is more time for the heat of combustion to soak into all the components of the combustion chamber (head, cylinder, piston, etc). This is where the KSB helps our engines warm-up quicker.


The way the KSB is designed and adjusted, it's predominant influence on the injection event timing, is in the lower engine rpm.

See the following illustration . . . .





As you can see, there is a substantial advancement of the injection event timing in the lower engine rpm. Further, as is shown, the effect tapers off moving up in the engine rpm.

Recognizing that shown above, if one has substantial static timing advance to begin with, yours may very well go way passed optimum timing for lower engine rpm, with applying the KSB.





Someone mentioned earlier if removing some of the spacer washers from the KSB (the M&H spacer kit includes additional spacers to be used with those already in the KSB) would help the over-advancement condition.

The answer is NO. Removing the washers effectively reduces the preload of the timing piston spring. This will in turn allow the timing advancement range to begin earlier effectively giving you more timing advance in the lower engine rpm..

cougar

That explains my hard time starting when it is real cold out (too much timing) and that is why I remove the spacer in the winter. I'll try it "unplugged" next winter.

Alwaysworking

if you remove the M&H shim you timing will be more advanced.

ClassA4x4

Ok, then what if I ADD a very thin shim (or replace the shim with a bit thicker one)? Will it retard the timing a bit, just enough that when the ksb is on, the timing will advance a bit?

Thanks in advance.

ClassA4x4

Originally Posted by ClassA4x4
Quote:
Originally Posted by Alwaysworking
if you remove the M&H shim you timing will be more advanced.


Ok, then what if I ADD a very thin shim (or replace the shim with a bit thicker one)? Will it retard the timing a bit, just enough that when the ksb is on, the timing will advance a bit?

Thanks in advance.

----------
Response from Alwaysworking . . .

In theory it will retard the timing because it increases the spring tension, but it will also limit the maximum timing travel on wot.

the standard recommendation is to not have power to an inter cooled engine, and to add power to a non inter cooled engine

ClassA4x4

I continued to tinker with my spacer installation and the following is my conclusion:

1. The spacer, despite claims it does not advance idle (low rpm) timing, does advance timing at idle, in addition to advancing the timing at higher rpms and at a wider range.
2. The cumulative effect of the spacer is 2.0 mm reduction of preload on the ksb spring. Yes there is a thick cover spacer but also a thinner washer added inside the ksb. The net difference is 2mm.
3. As reported earlier, the idle is higher when the ksb is off, and idle rpm goes down when the ksb is on, i.e with the spacer, the ksb over-advances the timing to a point that injection is too much within the compression stroke, retarding idle.
4. In order to neutralize the over-advancement when the ksb is on, i've increased the preload by 0.80 mm - that brings the preload reduction to only 1.20mm over stock, compared to the original-issue M&H spacer with 2.0mm reduction. I replaced one of the thin stock shims, which is 0.60mm, with a 1.4mm washer. This makes the effect of the ksb at idle rpm not discernible. I realize this also narrows the range of dynamic timing advance at higher rpms but surely still wider than stock, retaining 60% of the M&H capability.

Now, i really don't know the static timing of my IP in mm-lift or adv degrees, so yours may need a different preload inorder to neutralize the adverse effect of the ksb at idle. To begin with, my IP is set such that it's retarded a bit that when I start the engine it bucks a bit (a little hard to start) and idles rough; then I advance the timing by rotating the IP toward the head until the engine starts easily and idles smoothly. That is my static timing.

Rick 12v CTD

I just wanted to add to this thread that I have always run my heap with the dynamic timing piece with 1 tooth advanced and all the way away from the head. I know a lot of people begin to have issues with their timing and such with advanced timing with the timing spacer. I guess I'm the odd man out here because I threw the ip to the head so now I'm a tooth plus all the way to the head and I'm not getting any I'll effects with the dynamic timing piece. Almost feel like I need to skip another tooth and pull it away from the head and see what happens.

My results are vastly reduced smoke. Higher egts at light to mid throttle believe it or not. And I lost 3-4psi at wot. Oh and it seems to be significantly louder at all rpms.

I think Christmas time is when I will get the new head on since I can't have the truck down right now. When that happens I'll be going 2 teeth advance and taking the spacer out. See what happens then.

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dieselluvr

Interesting thread. I recently bought the spacer thinking that it retained stock timing at low RPM's and gradually increased it incrementally past what stock timing would be as the RPM's increased. This all makes it sound like I just wasted my money...

ClassA4x4

Not necessarily, it depends on your setup. Each is a different setup. On mine I still retain 60% of the benefit. For me it's a matter of finding the preload sweet spot. Some who are using it are perfectly satisfied wth it unmodified.

cougar

Thank you for confirming my comments in other threads on this subject.