Valve timing angles. Bad camshaft?

[skrillac]

Been working on an engine swap for awhile now. Putting a D905 into a Bx. Having trouble starting after all this work, and I'm thinking it's a timing issue. I have verified all 3 sets of dots line up on the gears, so I don't think that's it. The engine won't start unless I use glow plugs, and even then its definitely missing enough to not start.. I'll post a video below of what it sounds like following this.


I've rebuilt some of this so far, new rings, big end bearings, hone in cylinders and mic'd +- 0.01mm from spec (72 mm) in 6 spots all cylinders. Cleaned the pistons and rods in an ultrasonic and replaced the flat tappets because I turned the engine over pulling pistons and they all came out and got mixed up. I've had a shop clean up the head. They cleaned and lapped the valves. Put in new stem seals. Got the head back on with a new head gasket and the small oil o ring. Compression looks good cold, right at 400psi for all. I've pop tested and leak tested all injectors, pops right at 1900psi. Holds that pressure too for 10 seconds. Injection timing is right at 20 degrees btdc. And I've verified this for all cylinders with a dial indicator. Used spill timing method. So I don't think injection timing is to blame. I've also verified cylinder #1 TDC matches the flywheel mark with the dial indicator, so I don't think it's bent connecting rods.


Originally this engine was a fixed rpm BG type and its timing was set a bit retarded from spec. From what I remember around 10 degrees. Which is weird, because I was able to start it like that in my determining whether this engine was a good candidate for a swap, before doing any of the aforementioned work.

So at this point I've been checking angles relative to bdc tdc when valves open/close to see if maybe my camshaft is to blame.

According to the WSM:

Intake valve begins opening 14 degrees before TDC of exhaust stroke
Intake valve begins closing 30 degrees
after BDC of intake stroke
Exhaust valve begins opening 55 degrees before BDC of power stroke
Exhaust valve begins closing 14 degrees after TDC of exhaust stroke

I've measured the following so far:


#1 IV opens 2 degrees BTDC
#1 IV closes 30 degrees ABDC
#1 EV opens 40 degrees BBDC
#1 EV closes 4 degrees ATDC

#2 IV opens 8 degrees BTDC
#2 IV closes 30 degrees ABDC
#2 EV opens 50 degrees BBDC
#2 EV closes 14 degrees ATDC

#3 IV opens 5 degrees BTDC
#3 IV closes 30 degrees ABDC
#3 EV opens 50 degrees BBDC
#3 EV closes 18 degrees ATDC


I remeasured cylinder #1's valves and got different results from the first time


#1 IV opens 7 degrees BTDC
#1 IV closes 30 degrees ABDC
#1 EV opens 35 degrees BBDC
#1 EV closes 4 degrees ATDC

I'm sort of blaming these unprecise measurements on the digital dial indicator, and am currently waiting on an analogue one that is more accurate. I will remeasure all 3 cylinders again with the digital dial indicator and post here.

Just wondering if maybe I've overlooked something or whether someone else has ever measured valve angles and can spot something wrong right away or maybe something I'm doing wrong.

 

[skrillac]

after 30 secs of glow plugs

 

[North Idaho Wolfman]

In all my years I've never seen a bad cam.
You either have something set wrong on the timing gears or more likely you have the shims wrong under the pump.
I'm betting you also have the flywheel bolted up to the crank wrong thus all your measurements are wrong.

If it ran before you messed with it it should run again after you messed with it if you put everything in properly.

I would have to go threw the WSM for that motor to know if it is the case or not, but some motors require 4 gears to be aligned to set.
I've also seen the bottom gear put on the crank wrong causing bad timing setup.

 

[skrillac]

In all my years I've never seen a bad cam.
You either have something set wrong on the timing gears or more likely you have the aims wrong under the pump.
I'm betting you also have the flywheel bolted up to the crank wrong thus all your measurements are wrong.

If it ran before you messed with it it should run again after you messed with it if you put everything in properly.

I would have to go threw the WSM for that motor to know if it is the case or not, but some motors require 4 gears to be aligned to set.
I've also seen the bottom gear put on the crank wrong causing bad timing setup.

None of the gears have been pulled or adjusted. These flywheels only bolt up to the crank one way, as far as I know. I have opened the pump up for cleaning and did replace springs, but it's timing is right on the money, and there isn't any difference between cylinders. I'm fixing to test plungers and delivery valve pressure to rule that out. I don't know what you mean by aims under the pump.

I'm probably gonna just send off the injectors and pump to a diesel injection shop since I'm at my wits end.

 

[North Idaho Wolfman]

None of the gears have been pulled or adjusted. These flywheels only bolt up to the crank one way, as far as I know. I have opened the pump up for cleaning and did replace springs, but it's timing is right on the money, and there isn't any difference between cylinders. I'm fixing to test plungers and delivery valve pressure to rule that out. I don't know what you mean by aims under the pump.

I'm probably gonna just send off the injectors and pump to a diesel injection shop since I'm at my wits end.

It was a typo, Shims under the pump?
Did you use the shims under the pump that are original to the block?

I know the flywheels are supposed to only bolt up one way but I've seen quite a few that were not.
The timing is not set by anything internal in the pump.
It's set by the front gears under the gear case and the shims under the Injection pump.

 

[skrillac]

It was a typo, Shims under the pump?
Did you use the shims under the pump that are original to the block?

I know the flywheels are supposed to only bolt up one way but I've seen quite a few that were not.
The timing is not set by anything internal in the pump.
It's set by the front gears under the gear case and the shims under the Injection pump.

I took all the shims out. Earlier I was using a coat hanger through the glow plug hole to determine tdc for fuel timing, because I suspected maybe I was off from the flywheel marks. After using the dial indicator to measure this several times, I've verified I'm not. However, this is useful in explaining a few things maybe.

The black dots correspond to flywheel marks. Red dots are what I measured with a coat hanger for fuel spill timing for cylinder #1. From this you can see I was measuring about 10 degrees off from flywheel marks. With the coathanger and no shims, I measured 30 degrees btdc. I've measured this again with a dial indicator since this again with no shims and its actually dead on 20 degrees, matching the both flywheel marks for tdc and 20 degrees btdc. I have 4 shims between both the junk engine and the donor engine. Donor engine had x2 2hole shims which I mic'd at 0.20mm each. Junk engine had x1 2hole shims and x1 no hole shims, respectively 0.20mm and 0.30mm. For testing purposes I tried all 4 together, and with a coathanger measured 15degrees btdc. Finally, I took out the no hole shim leaving x3 2hole shims and measured with the coathanger 20 degrees btdc.

I have since discovered with more accurate tools, ie dial indicator, that all of these red dot measurements were wrong. Potentially I'm measuring things wrong again with this digital dial indicator. When the analogue one comes and I remeasure I think I'll have my answer.

The wsm doesn't give minimum allowed for the valve open/close angles. Only numbers of what they are I guess from the factory. Do you know if there are any and when I'd be able to call it a bad cam, since replacing it is gonna require picking the engine back outta there to get to it. Would prefer to have an obvious reason to do all that instead of "I'm off by 5degrees on a few valves it must be the cam" unless the wsm is explicitly saying being off at all is bad.

 

[North Idaho Wolfman]

I took all the shims out.

This is 100% of your problem.

Forget all the measurements and degrees and such, you're really over thinking this.

Put the stock shims back under the pump, make sure the valve lash is set properly and the engine will start and run unless there is damage to the pump, the governor, or the fuel linkage (internally).

I've worked on and rebuilt quite a few Kubota engines and I've yet to have to even look at the flywheel for any marks or measurements to get an engine to run properly.

 

[skrillac]

This is 100% of your problem.

Forget all the measurements and degrees and such, you're really over thinking this.

Put the stock shims back under the pump, make sure the valve lash is set properly and the engine will start and run unless there is damage to the pump, the governor, or the fuel linkage (internally).

I've worked on and rebuilt quite a few Kubota engines and I've yet to have to even look at the flywheel for any marks or measurements to get an engine to run properly.

I've been working on this engine for several months so excuse my silly mistakes and rambling.

Now that I'm thinking about it more, I did swap out it's governor mechanism. The donor block was a bg and had the 2 fork governor arm. I put the 3 fork governor inside and removed shims to get to the 19-21 degrees btdc number the wsm gives for the bx2670. I've replaced a governor arm on a d1105t before so I think I know what I'm doing there. And I don't think the governor itself would affect starting, just the start spring that pulls the fuel pump rack all the way to the left. I haven't messed with any idle screws or the screw some turn all the way out on the gear cover to "roll coal". Also since I don't think I mentioned it, I have a few injection pumps I've collected over the years. I've swapped all of them in and it hasn't made any difference.

Are you sure I should go back to stock shims, considering stock was with fixed 1800rpm in mind? I'm definitely gonna be running it over 2000rpm alot in the future. From what I've seen from guys who do this they usually advance it a bit with higher rpms in mind.

I think I will try putting those shims back under the pump and if it doesn't start then remeasuring spill timing and rechecking compression again and updating here. Worst case, I'm thinking I should probably just send the pump and injectors off for a second opinion. I haven't found any places local, can you recommend any?

 

[North Idaho Wolfman]

I've been working on this engine for several months so excuse my silly mistakes and rambling.

Now that I'm thinking about it more, I did swap out it's governor mechanism. The donor block was a bg and had the 2 fork governor arm. I put the 3 fork governor inside and removed shims to get to the 19-21 degrees btdc number the wsm gives for the bx2670. I've replaced a governor arm on a d1105t before so I think I know what I'm doing there. And I don't think the governor itself would affect starting, just the start spring that pulls the fuel pump rack all the way to the left. I haven't messed with any idle screws or the screw some turn all the way out on the gear cover to "roll coal". Also since I don't think I mentioned it, I have a few injection pumps I've collected over the years. I've swapped all of them in and it hasn't made any difference.

Are you sure I should go back to stock shims, considering stock was with fixed 1800rpm in mind? I'm definitely gonna be running it over 2000rpm alot in the future. From what I've seen from guys who do this they usually advance it a bit with higher rpms in mind.

I think I will try putting those shims back under the pump and if it doesn't start then remeasuring spill timing and rechecking compression again and updating here. Worst case, I'm thinking I should probably just send the pump and injectors off for a second opinion. I haven't found any places local, can you recommend any?

The shims have nothing to do with RPM limits.
They just have to do with Injection timing.
The shims match the block and not the pump.
So no matter what pump you use you should always use the same shims.

The tolerance on the shims is so tight that adding RTV on the shims will change the timing enough where it will not run, so clean install is important.

Also on a lot of the governor linkages have 2 slots where the rack on the pump can engage the governor, but only one location is right.

 

[Russell King]

Oregon fuel injection for rebuild

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Oregon Fuel Injection specializes in the repair of diesel fuel injection systems, replacement diesel parts, performance parts, drive-in service, repairs and diagnostics.

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[skrillac]

@North Idaho Wolfman

I think you were right . I put those same injection shims (x2 2-hole shims) back under the pump. Went ahead and rechecked compression, looked good. After the shim change, spill timing looks somewhere between 13-14 degrees BTDC. I'm fairly sure that is accurate, as I used a degree wheel in addition to the flywheel marks. I've bled the injectors a few times and get similar results each time, so I'm fairly confident the remaining issue preventing normal starting is an issue with the injectors. What do you think?


for some reason the site isn't letting me embed media, so I've shared links to youtube videos below

#1 - first time starting after bleed. engine stopped by itself, probably from lack of fuel
#2 - second time starting after bleeding again. really sounds like a bad injector to me
#3 - third time starting after bleeding for a third time. sounds similar to the first video

 

[North Idaho Wolfman]

Do you have mutiple injectors or mutiple injection pumps?

Also pull the side coive3r off and take a picture of the governor to rack connection (pin on fuel injection pump) .

 

[skrillac]

Do you have mutiple injectors or mutiple injection pumps?

Also pull the side coive3r off and take a picture of the governor to rack connection (pin on fuel injection pump) .

@North Idaho Wolfman

I do have multiple injectors, however most of them didn't test good. I am using the three from the junk block currently, as they are newer and pop tested ok. Now that I'm remembering it, one of these three i'm currently using was a bit iffy when I tested it. You may agree if you see the videos below. I also do have another spare injector that pops ok, but at a bit lower than spec. Around 1700-1800 psi. So all in all, I have 4 injectors. I also have multiple injection pumps. The one I'm currently using was also from the junk block, and I've replaced the springs / orings in it and the middle plunger (oem part, cylinder #2). I still have the old pump, which I've only disassembled the top of to clean delivery valves in an ultrasonic. I also have another pump I bought on ebay years ago from someone selling it in pieces as they forgot how to put it together . Its had orings / springs replaced in it as well.


injector #1 spray pattern
injector #2 spray pattern. a bit iffy, probably bad now that I'm rewatching it
injector #3 spray pattern

here's behind the speed control plate, like you asked


edit: now that i've thought about this some more, maybe it has to do with the spring connecting the control plate lever to the governor arm (bigger spring, #2 in diagram below) or maybe the idle limit spring (#12 in diagram below).

 

[lugbolt]

verified cylinder #1 TDC matches the flywheel mark with the dial indicator, so I don't think it's bent connecting rods.

that's not really the right way to do it. All you're doing is verifying that the piston is up as far as it can go. A bent rod normally presents itself as the piston being further down in the cylinder than specified in the shop manual, at TDC which can only be measured with the head off. Or at least that's the way I've always done it.

if valve timing was off, compression would be high or low. Being low, it could still be off, but could be other things as well

are you checking compression pressure with the injection disabled such that no fuel can get into the cylinder?

 

[skrillac]

that's not really the right way to do it. All you're doing is verifying that the piston is up as far as it can go. A bent rod normally presents itself as the piston being further down in the cylinder than specified in the shop manual, at TDC which can only be measured with the head off. Or at least that's the way I've always done it.

if valve timing was off, compression would be high or low. Being low, it could still be off, but could be other things as well

are you checking compression pressure with the injection disabled such that no fuel can get into the cylinder?

I've thought about this some more. I was able to get the engine running per the videos earlier in the thread. However, as soon as it starts it shuts down. That might be because of the governor arm moving the fuel rack as its supposed to. I looked around some more and realized I didn't swap the start spring. So I was using the start spring the donor engine came with, but not its governor. I had swapped the 3 arm governor in and was still using the same start spring. I took a look at the springs, and the one from the junk block is a bit shorter, so it will probably exert a stronger force pulling the fuel rack forward. Meaning if I use that shorter spring, the governor won't completely kill the engine like it is doing now, and it will allow the engine to idle. At least that's what I'm thinking. I'm gonna try swapping the start spring and see where that takes me.

 

[skrillac]

Ok so the spring change really helped. Engine now runs and idles, albeit a bit low. Also, there is no throttle response whatsoever. I wonder if the idle limit spring (#12 in the diagram above) needs to be turned in a bit. But that still leaves the issue with unresponsive throttle. Has anyone ever swapped to a 3 fork governor arm and had this issue?