When to advance timing on BMC 1.8

[thematt]

Hello all,

 

I've completed by fuel system refit for my surplus BMC 1.8 (westerbeke w50).

 

There are new fuel filters, lift pump, rebuild injection pump, new glow plugs, and new injectors (all 4) tighter to spec (12 ft/lbs). 

 

Successful bled everthing according to the manual and got her fired up. She runs a bit rougher than normal.

 

I was cautious to try and get the timing lined up. The previous pump was quite advanced, rotated toward the outside of the engine. The injectors were also in rough shape. My pump is the mechanical variant without the torsion bar.

 

I don't have much smoke to speak of, perhaps a tiny amount that may be steam it's humid at 10 degrees today.

 

The issue: However, when running I'll hear a 'Lumpy' or rocky feeling combustion (I believe) it's pretty consistent. I do not believe it was there before. It's more pronounced at lower rpm it increases with rpm until it's not very noticable.

 

I slackened the Union nuts in the fuel lines and was able to make the engine very lumpy all the time on 3 cylinders. So I know all are firing at some point. The first and 4th fuel line sprays everywhere, while 2 and 3 are a little more relaxed at least not misting.

 

I hope this isn't too much info. Basically, I'm looking to see if the timing could be the culprit here? Perhaps too advanced to cover for the older injectors? Perhaps I installed it not advanced enough?

 

Possible bad new injector?

 

Another thing I'm playing with for a future task is perhaps too much back pressure. I have way to much rise ~1.5M (60inches). The lump feeling does seem to coincide with the wet exhaust discharge interval. Perhaps I didn't notice it before?

 

Another, thought I had: I adjusted the valve lash, if I over did it when tightening down could this cause that issue? Though, it ran fine with the previous injection pump.

 

Any insight or thoughts would be much appreciated! Thank you!

 

 

[Tony Brooks]

53 minutes ago, thematt said:

Another, thought I had: I adjusted the valve lash, if I over did it when tightening down could this cause that issue?

 

Yes, at low speed particularly, but I would also expect poor cold starting and worse lumpiness when idling and hot.

 

55 minutes ago, thematt said:

Successful bled everthing according to the manual and got her fired up. She runs a bit rougher than normal.

 

I was cautious to try and get the timing lined up. The previous pump was quite advanced, rotated toward the outside of the engine. The injectors were also in rough shape. My pump is the mechanical variant without the torsion bar.

 

How did you set the timing, by using the timing pointer and line on the pump, or setting the pointer up from the timing marks and using the tool to set the pointer. (Assuming the 1.8 uses an adjustable timing pointer and needs the tool to take the backlash out of the drive chain).

 

I have a feeling that the mechanical DPA pump may have a timing mark under the leak back pipe connection flange, but don't hold me to that, look in the manual.

 

I understand from @Tracy D'arth that 1.8s can suffer from stretched timing chains, so the camshaft oscillates, more noticeably at lower speeds. You may be able to hear the chain thrash by listening close to the timing cover. I also understand the 1.8s have been known to suffer timing chain jumping a tooth when they are stretched. I doubt it has jumped, but may be worn.

1 hour ago, thematt said:

Basically, I'm looking to see if the timing could be the culprit here?

 

Well, ensure that you put witness marks on the pup flange and engine so you know where to put it back, and try adjusting it manually, I understand many mechanics do it that way if they do not have the tool to set the pointer.

 

[thematt]

27 minutes ago, Tony Brooks said:

How did you set the timing, by using the timing pointer and line on the pump, or setting the pointer up from the timing marks and using the tool to set the pointer. (Assuming the 1.8 uses an adjustable timing pointer and needs the tool to take the backlash out of the drive chain).

 

I have a feeling that the mechanical DPA pump may have a timing mark under the leak back pipe connection flange, but don't hold me to that, look in the manual..

 

The timing was set with a marker on the injection pump hub. There is a mark on the pump flange as well. Thankfully it lines up with the mark on the hub. This is how I could tell the original setting was quite advanced. I attached a file of the original pump the mark is between the yellow lines and very hard to see in the photo. But it's there!

 

34 minutes ago, Tony Brooks said:

 

Yes, at low speed particularly, but I would also expect poor cold starting and worse lumpiness when idling and hot.

 

Hmm, I'll save that for a double checking then if I'm still stumped thank you!

 

35 minutes ago, Tony Brooks said:

I understand from that 1.8s can suffer from stretched timing chains, so the camshaft oscillates, more noticeably at lower speeds. You may be able to hear the chain thrash by listening close to the timing cover. I also understand the 1.8s have been known to suffer timing chain jumping a tooth when they are stretched. I doubt it has jumped, but may be worn.

 

Used a large screw driver as a stethoscope, I can hear chainlike sounds but nothing particularly thrashing sounding. How loud of a sound am I looking for?

 

38 minutes ago, Tony Brooks said:

Well, ensure that you put witness marks on the pup flange and engine so you know where to put it back, and try adjusting it manually, I understand many mechanics do it that way if they do not have the tool to set the pointer.

 

 

I'll give it a go. Any guidance on what too advanced behaves like, how about not advanced enough?

 

Thanks for always being quick with advice. It's very much appreciated.

[Tony Brooks]

1 hour ago, thematt said:

Hmm, I'll save that for a double checking then if I'm still stumped thank you!

 

Too large valve clearances, within reason, do not tend to affect lumpiness of the engine, but too tight ones do, so err on the slack side.

 

1 hour ago, thematt said:

Used a large screw driver as a stethoscope, I can hear chainlike sounds but nothing particularly thrashing sounding. How loud of a sound am I looking for?

 

I understand that 1.8 timing chains have been known to wear through the timing cover, so fairly loud and possibly squeaking.

 

1 hour ago, thematt said:

The timing was set with a marker on the injection pump hub. There is a mark on the pump flange as well. Thankfully it lines up with the mark on the hub. This is how I could tell the original setting was quite advanced. I attached a file of the original pump the mark is between the yellow lines and very hard to see in the photo. But it's there!

 

I can see the marks and agree that they did not line up, but is the pointer in the right place? You need a tool for that, that allows you to take the slack out of the timing gear and reset the marker. It appears from the paintwork that the pointer and pump position as it was from the factory, but that does not seem credible, so maybe the engine has been repainted. I doubt you will find a timing tool, so maybe adjusting the pump by trial and error is the only practical way. As you have the photo, have you tried setting the pump as it is in the photo to see if it runs better.

[Kingdom Isambard Brunel]

It looks to be over advanced to me.

Retarded a long way results in white smoke, advancing from there should make it run cleaner and smoother. Over advance will make it harsher running with a bark to the exhaust.

The problem with this engine in a boat is that we want it to run smoothly at very low revs, not what it was designed to do specifically.

Why is there no torsion bar in the pump? I can see no reason for its omission, the drive is the same with either the hydraulic or the mechanical governor. Without it there will be backlash as the pump drive shaft is floating.

[thematt]

8 hours ago, Tony Brooks said:

 

Too large valve clearances, within reason, do not tend to affect lumpiness of the engine, but too tight ones do, so err on the slack side.

 

 

I understand that 1.8 timing chains have been known to wear through the timing cover, so fairly loud and possibly squeaking.

 

 

I can see the marks and agree that they did not line up, but is the pointer in the right place? You need a tool for that, that allows you to take the slack out of the timing gear and reset the marker. It appears from the paintwork that the pointer and pump position as it was from the factory, but that does not seem credible, so maybe the engine has been repainted. I doubt you will find a timing tool, so maybe adjusting the pump by trial and error is the only practical way. As you have the photo, have you tried setting the pump as it is in the photo to see if it runs better.

 

Re. Valve clearance:  definitely adding it to the list to check again. Sounds like I might have dragged the tightening screw too tight when I secured the lock nut.

 

Re. Chain wear. The sound reminds me of a bike chain rolling over a sprocket at high speed. Nothing too loud or squeeky. I'll triple check though because I haven't listened since I replaced the pump.

 

Re. Timing. I see what your getting at now. The marks weren't adjusted and may well be factory. The only thing I have to go off of is the engine sounded fine before. I lined the newly installed pump up with the old advanced timing as best as I could. Might be time to reset to factory timing and slowly advance until it runs just right.

 

5 hours ago, Kingdom Isambard Brunel said:

It looks to be over advanced to me.

Retarded a long way results in white smoke, advancing from there should make it run cleaner and smoother. Over advance will make it harsher running with a bark to the exhaust.

The problem with this engine in a boat is that we want it to run smoothly at very low revs, not what it was designed to do specifically.

Why is there no torsion bar in the pump? I can see no reason for its omission, the drive is the same with either the hydraulic or the mechanical governor. Without it there will be backlash as the pump drive shaft is floating.

 

Re timing: I'll follow your advice and start from the factory marks and slowly advance. The photo is of the original pump, is it possible it was advanced to hide tired injectors?

 

Re torsion bar: there just isn't one as far as I can tell. I've attached the schematics from the manual where it shows the bar (89) in the hydrolic governed pump and lack there of in my style pump. Further I've included a photo of my pump drive spline area, there doesn't appear to be a spot for a bar. Nor was there one when I pulled the old pump out. Is that a big piece I'm wrong about?

Edited May 16 by thematt
better cropped photo and some grammar fixes

[Tony Brooks]

33 minutes ago, thematt said:

Re torsion bar: there just isn't one as far as I can tell. I've attached the schematics from the manual where it shows the bar (89) in the hydrolic governed pump and lack there of in my style pump. Further I've included a photo of my pump drive spline area, there doesn't appear to be a spot for a bar. Nor was there one when I pulled the old pump out. Is that a big piece I'm wrong about?

 

I have never seen one on the mechanically governed DPA and even on the hydraulic pumps they run OK without the torsion bar. I think it is there to slightly twist a short section of the drive spline to avoid excessive wear caused by spline chatter at low/very low speed. It has been reported here that Calcutt confirmed a torsion bar is not needed.

[thematt]

7 minutes ago, Tony Brooks said:

 

I have never seen one on the mechanically governed DPA and even on the hydraulic pumps they run OK without the torsion bar. I think it is there to slightly twist a short section of the drive spline to avoid excessive wear caused by spline chatter at low/very low speed. It has been reported here that Calcutt confirmed a torsion bar is not needed.

That's a relief! Thank you.

[thematt]

On 16/05/2025 at 04:49, Kingdom Isambard Brunel said:

It looks to be over advanced to me.

Retarded a long way results in white smoke, advancing from there should make it run cleaner and smoother. Over advance will make it harsher running with a bark to the exhaust.

The problem with this engine in a boat is that we want it to run smoothly at very low revs, not what it was designed to do specifically.

Why is there no torsion bar in the pump? I can see no reason for its omission, the drive is the same with either the hydraulic or the mechanical governor. Without it there will be backlash as the pump drive shaft is floating.

 

I think we have a winner here. I rotated the pump back toward the "factory setting" and the engine became smoother. I've gained about 100rpm at wide open throttle underload and get a bit less black/grey smoke. The pump is still slightly advanced but no where near where it was. 0 white smoke at all. So I may continue to edge back within reason.

 

Some of that smoke is from the engine being overloaded I'm sure. Peak rpm in the slip was 2540. In neutral the engine easy can hit 3200.

 

Could it be the pump was advanced by the previous owner to make up for worn / bad injectors?

 

Still to do: double check valve lash isn't too tight and fix back preasure from exhaust run. Getting there little by little.

 

[Tony Brooks]

22 minutes ago, thematt said:

Could it be the pump was advanced by the previous owner to make up for worn / bad injectors?

 

There is no answer to that, I have long given up trying to understand what some people do to their engines. I can't see how altering the injection timing would have much effect on compensating for worn injectors, unless the smoke the injecrs produced was mistaken for a timing problem.

 

I

25 minutes ago, thematt said:

Some of that smoke is from the engine being overloaded I'm sure. Peak rpm in the slip was 2540. In neutral the engine easy can hit 3200.

 

Is that all, I doubt the 1.8 is much different from the 1.5 and those had the maximum revs (off load) set to 4400 - not that I would be happy taking one up to that.  However, this is just accademic as long as is running weel and delivers adequate power

 

[thematt]

Apologies, I had assumed all 1.8s were the same. My engine is designed for 3200 max according to my manual.

[Tony Brooks]

10 minutes ago, thematt said:

Apologies, I had assumed all 1.8s were the same. My engine is designed for 3200 max according to my manual.

 

Nothing to apologise for. Is that the off load setting or the maximum speed on load? Even measurement has variations, the continuous rating (which the 3200 may be), the so-called emergency rating, which is higher and time limited, then the maximum off load speed. Put a load on the engine and the speed will drop. I quoted the figure for the 1.5 (the 1.8 may be different) taken from the Newage manual, and I think I have seen that figure in a BMC automotive manual.  If you have a Westerbeake manual, the 3200 may be something they say for long term reliability. In any case the pump will be set for volume of fuel delivered at a certain speed when on the test bench, then the maximum speed will be set by the throttle stop on the running engine.

[thematt]

22 minutes ago, Tony Brooks said:

Is that the off load setting or the maximum speed on load?

I'm uncertain. I believe the on load given the power curve supplied:

 

Both before and after fuel system work I did the engine wasn't able to make the full 3200 rmp loaded at the slip (or at sea). Unloaded, no problem, and then some.

 

I gained a few rpm, but mostly got rid of a bunch of white smoke at WOT even in the advanced state it was in, stopped a diesel leak from the pump, and improved over heating at WOT. The injectors were rough looking when I pulled them.

 

It's starting to run smoother now, but I believe the grey / black smoke at wot is incomplete combustion and not a timing issue at this point right? My next thought is the previous owner had installed ~60 inches of exhaust rise ~1.5M. Feels like a good next place to look. I've managed to confirm that there's a strange vibration / change in sound just before the water gets ejected that hints at that as well.

 

Thanks for all the feedback and support.

 

[Tony Brooks]

6 hours ago, thematt said:

 

It's starting to run smoother now, but I believe the grey / black smoke at wot is incomplete combustion and not a timing issue at this point right?

 

I agree, if anything is holding the revs down then the governor will go to full fuel to try to accelerate the engine, which it will not be able to do, and the swirl in the combustion and pre-combustion chambers is less that at the rated full speed, so yes, that is incomplete combustion, but "normal" with a slightly overlarge prop. In my view it is nothing to worry about, just ease the throttle back until the smoking stops, and the revs probably drop very slightly.

 

I am not commenting upon the exhaust rise because my expertise is in inland boats with maybe only 10 inches or so rise, but I do know that sea boats and others in hard water areas, like the Thames, can suffer from scale build up in the mixing elbow, and that restricts the exhaust gas flow, so if you have not done so already, (I can't remember) make sure the mixing elbow is clear and also that the exhaust hose has not delaminated on the inside, or someone has left a rag in it. I have known delamination to be forced into the pipe bore when going faster an dpartially block the pipe, but the exhaust often hisses when that happens and only produce a sort of fine spray of cooling water.

[thematt]

Thanks Tony! I have a scope camera I'll send in to check things out. 

 

The rule of thumb I've heard from legends like Nigel Calder is the rise should be no more than 40inches ~1M from the lowest point in the system. So I have about 50% too much. One must meet that and still remain 18 inches ~45cm above the waterline and drop 12inchs ~30cm from the mixing elbow.

 

I'll report back in ~ a week on those results.