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Discussion Starter · #161 ·
On my race bike builds, I check PTV clearance at 8 degrees BTDC for the intake and 8 degress ATDC for the exhaust. You want at least .050" on the intake and .075" on the exhaust. Of course on a 24v diesel it's probably different.
Cool- thanks for the tip! I'm always looking for other viewpoints and experience since I can't find too much info about other builds that have been done on these engines.

I probably should have checked it with the stock pistons to see what they had originally, but adding the head gasket will give me another 0.052", so I think I'll be in the clear.
 

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You are for sure. I missed the "no headgasket" on my first read. You should have checked the deck height, too. Deck height has a impact on compression ratio. Kudos for using a different piston!
 

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looking good with the head gasket installed should be good even with hot exhaust valves, the pistons, valvetrain, and reliefs look like they were made for it ;) (y) nice workup

You mention you could have taken another .010" off the deck, will you have to do any additional things in regard to valve timing, I know years ago (Eons now) when we would go to "zero" deck blocks on Overhead cam 4 cyl we would have to get a little creative with bushings and offset keys to index cam timing to ensure optimum valve timing, and net cylinder pressure, sorry for the dumb inquiry but my experience/Exposure with late model OHC is pretty limited, only fooling with a couple of 4.6 Mustangs :oops: :unsure:
 

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After rotating past TDC, I pulled the head back off, and found that I have at least 0.050" clearance with the valves closed. Also, the valve reliefs on the Mercedes piston appear to be in exactly the right spot for the valves. If you look at this picture closely you can see the outline of the valve, and if you follow it, the outline of the relief on the piston. Same on the piston side. Amazing! Almost like VM Motori and Mercedes colluded on these engines or something.
At one point, you thought Mercedes and VM Motori shared the same piston rings. Didn't you also think the Sprinter 3.0L used the same piston and rings as the EcoDiesel?

 
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Discussion Starter · #165 · (Edited)
You are for sure. I missed the "no headgasket" on my first read. You should have checked the deck height, too. Deck height has a impact on compression ratio. Kudos for using a different piston!
I don't have a great way of measuring deck height, but I did my best using measured/stated values and came up with ~ 16:5 compression ratio on a stock engine. For this build, I think it is actually a little lower because the piston looks to be about 0.010" in the hole, and I had assumed zero for the calculation. Also, these heads have no chamber to speak of, so I used the dish on the piston for chamber volume. Further, the Mercedes piston had a slighly smaller dish (2 cc smaller), so it may end up close to 16:5 after all.

Regardless, I'm expecting that the ECM will be able to make up for minor calibration differences. I also have a GDE tuned ECM, so I will experiment with that too.

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Discussion Starter · #166 ·
looking good with the head gasket installed should be good even with hot exhaust valves, the pistons, valvetrain, and reliefs look like they were made for it ;) (y) nice workup

You mention you could have taken another .010" off the deck, will you have to do any additional things in regard to valve timing, I know years ago (Eons now) when we would go to "zero" deck blocks on Overhead cam 4 cyl we would have to get a little creative with bushings and offset keys to index cam timing to ensure optimum valve timing, and net cylinder pressure, sorry for the dumb inquiry but my experience/Exposure with late model OHC is pretty limited, only fooling with a couple of 4.6 Mustangs :oops: :unsure:
Good questions.

Since the goal was to come up with a simple solution to the inavailability of key parts (mainly oversized pistons), I'm hoping I can get away with using the stock cam timing, stock tuning, etc. I do have a degree wheel, but the timing tool pretty much locks everything into one location, so to stray from the stock timing would mean modify the timing tool, and making offset keyways (not trying to go there LOL!)

For now, I'm treating this as an experiment. If it is successful, I'm sure there will be some other improvements that can be built into the next one.
 

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Discussion Starter · #167 ·
At one point, you thought Mercedes and VM Morori shared the same piston rings. Didn't you also think the Sprinter 3.0L used the same piston and rings as the EcoDiesel?

Correct! The only difference is that the Mercedes rings have a Chrome top compression ring whereas the factory top ring is Moly
 

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Good questions.

Since the goal was to come up with a simple solution to the inavailability of key parts (mainly oversized pistons), I'm hoping I can get away with using the stock cam timing, stock tuning, etc. I do have a degree wheel, but the timing tool pretty much locks everything into one location, so to stray from the stock timing would mean modify the timing tool, and making offset keyways (not trying to go there LOL!)

For now, I'm treating this as an experiment. If it is successful, I'm sure there will be some other improvements that can be built into the next one.
I had forgotten about the cam timing tool(s) but I'd say that is going to work like a champ, I know we used cam timing tools while doing my grandsons WRX and it actually worked out perfectly with the tensioners that are utilized on that engine, enjoying you build data and progress(y)
 

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Discussion Starter · #170 ·
A quick note about something. I was looking for a tightening spec in the factory service manual and came upon this illustration:

Rectangle Font Parallel Circle Number



The Nural pistons are marked "1-2-3 Only" and "4-5-6 Only" with a directional arrow; however, with the Nural pistons, the arrow always points to the front of the engine. I don't know why VMM couldn't go through the trouble to switch the direction of the arrow mark on the right pistons since they are already specific to that side. Things that make you go "Hmmm?".
 

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It may be that all 6 pistons are the same, but some feature of the piston (maybe valve reliefs, or pin offset) requires that a specific "side" of the piston be to the outboard side of the engine. By indicating that the arrow points one direction on one bank, and the opposite direction on the other bank, they can use a single part number for the piston (qty. 6 per engine). This means they can create one casting (or forging), one production router that states how to make the piston, and one production line that makes all the pistons. This considerably simplifies production and reduces costs, but makes assembly slightly more complicated because the assembler has to check which way he installs the piston.

If they follow the Nural method and change the direction of the arrow, they then have to have 2 part numbers, one for each bank (qty. 3 of part A and qty. 3 of part B per engine). Both part numbers likely use the same casting, but each needs it's own router to indicate the proper direction of the arrow, and possibly 2 different production lines each with different tooling and cnc programming, to make the 2 different part numbers. This is a lot of additional up-front production cost which is hard to justify if all it does is make a few arrows point the same direction.

Another (possibly better) way to do it that I have seen, is to have the arrow on the piston point outward (away from crank centerline). Then the same piston can be used for both banks (qty. 6 of one part number per engine), and the instruction indicates that the arrow on the piston always points outward. This simplifies production and reduces cost; but also provides a consistent, easy to follow assembly method.
 

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Discussion Starter · #172 ·
It may be that all 6 pistons are the same, but some feature of the piston (maybe valve reliefs, or pin offset) requires that a specific "side" of the piston be to the outboard side of the engine. By indicating that the arrow points one direction on one bank, and the opposite direction on the other bank, they can use a single part number for the piston (qty. 6 per engine). This means they can create one casting (or forging), one production router that states how to make the piston, and one production line that makes all the pistons. This considerably simplifies production and reduces costs, but makes assembly slightly more complicated because the assembler has to check which way he installs the piston.

If they follow the Nural method and change the direction of the arrow, they then have to have 2 part numbers, one for each bank (qty. 3 of part A and qty. 3 of part B per engine). Both part numbers likely use the same casting, but each needs it's own router to indicate the proper direction of the arrow, and possibly 2 different production lines each with different tooling and cnc programming, to make the 2 different part numbers. This is a lot of additional up-front production cost which is hard to justify if all it does is make a few arrows point the same direction.

Another (possibly better) way to do it that I have seen, is to have the arrow on the piston point outward (away from crank centerline). Then the same piston can be used for both banks (qty. 6 of one part number per engine), and the instruction indicates that the arrow on the piston always points outward. This simplifies production and reduces cost; but also provides a consistent, easy to follow assembly method.
I think you're right on this, but as specific as they get on all other aspects of the engine parts and assembly, it surprises me that they leave room for error here.
 

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Discussion Starter · #175 ·
Timing hardware is in. Everything seems to be rotating smoothly, so I put the timing covers on. Next will be valve covers and exterior cooling lines. I may need to order some more silicone hose for the bypass before going further, but we'll see.

As an aside, I took one of my trucks on a 700 mile round trip last week. It ran flawlessly and got ~26 mpg(indicated). It was over 27, but a couple trips over the Grapevine in SoCal dropped it down a bit. This one has about 10k miles on the rebuild now.



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Discussion Starter · #178 ·
Got everything hooked up and checked, but it won't start. No codes are coming up. Spent part of yesterday troubleshooting, and I believe I have it narrowed down to the HPFP. There is fuel to the pump, but nothing coming out, and 8 volts to the Fuel Quantity Solenoid. I'm going to do a little more experimenting, and then swap out the injection pump.
 

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Got everything hooked up and checked, but it won't start. No codes are coming up. Spent part of yesterday troubleshooting, and I believe I have it narrowed down to the HPFP. There is fuel to the pump, but nothing coming out, and 8 volts to the Fuel Quantity Solenoid. I'm going to do a little more experimenting, and then swap out the injection pump.
The solenoid uses PWM so normal meters wont give an acurrate reading. Check your return flows from the injectors and see if its really high.
 

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Discussion Starter · #180 ·
The solenoid uses PWM so normal meters wont give an acurrate reading. Check your return flows from the injectors and see if its really high.
Thanks! I figured out that the solenoid itself was stuck, so I hooked it up to a 12VDC supply and popped it loose. Shortly after that I was able to start it.
 
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