Valve clearanance/valve train issue with Lister CS

[mikenash]

Hi guys.

I have been browsing here for a while while playing with an old CS and appreciating all the wealth of wisdom and experience.

Perhaps someone can help me with a dilemma - excuse me if I seem long-winded; it seemed a detailed description was in order.

I can't understand how to post images here?

Down here at the bottom of the world in New Zealand I have a 1943 CS - the ID plate says # CS43345 and 5.6 HP and Spec 5/1/35 and RPM 650.650

Its provenance is unknown except that I got it partially seized and with a bent exhaust pushrod.  The previous owner stated it was "either hydrauliced or something like that and the pushrod will bend as a safety valve" - in his opinion

I have had the head, piston, conrod, barrel etc off and stripped.  Big-end shells, pin-to-bush etc seem really good

For some reason (possibly related to the problem below) it had two head gaskets fitted - both shot

I have cleaned all the sludge out of the crankcase and inspected the crank and cam and they looked OK.

Yesterday I stripped the head and cleaned out all the old carbon and looked at the seats (90%) and guides (70% but serviceable) and cleaned out all the old sludge around the springs etc

Today - after cleaning everything thoroughly - I refitted barrel, piston, head etc

Before fitting the head I put a straight-edge across the top of the barrel with the piston at TDC and there's a just-visible smidgen of a gap.  It seemed to me I was justified in fitting the head on the assumption that the thickness of the ring of the head-gasket would provide an approximation of a working clearance piston-to-head - figured I'd get some lead or plasti-gauge tomorrow, Monday, and have a proper measure

I torqued the head down, fitted pushrods and rockers, rotated the engine so the intake valve was fully open, set the exhaust valve clearance to around 17 thou, rotated the engine further, and found the exhaust valve was hitting the piston.

I increased the valve clearance incrementally until, at a ridiculous 2.5mm (approx 1/10th of an inch) the engine would rotate without contact.  I guess the exhaust-open duration is about half what it should be?

Things I checked:

Short pushrod on exhaust, longer on intake

Cam followers, pushrod ends, "tappet" adjusters etc all clean

Cam timing seems OK (line on cam gear tooth is between dots on two teeth of idler gear)

Took the head back of and looked at valves etc and re-assembled.

Same result?

What am I missing?  It seems to me something in the exhaust valve-train is about 1/8 inch longer than it should be?

Maybe I have made some dumb newbie mistake?

I'd appreciate any thoughts

Thanks, Mike

[Gippslander]

Maybe the cylinder block has been machined too many times eg it is too low

[Combustor]

Hi there Mikenash,
                          Am sure there are experts here who can pinpoint your problem, but if you are sure the timing gears are correctly meshed, then time to look elsewhere. The hollow cams are fixed to the camshaft with taper pins. Is it possible that a pin is broken or wrongly fitted ? Time to check valve train timing. First properly locate TDC. Rig a pointer near flywheel timing marks. Pull injector and poke a rod down on the piston.  Rotate crank till rod is say 20mm down on piston before TDC, mark flywheel at the pointer. Then mark again when say 20 mm down after TDC, Measure half way between flywheel marks and this is accurate TDC. Now rotate and watch valves at the junction of intake and exhaust strokes (not compression stroke). Exhaust valve should be just closing and intake about to open right at TDC. If this is not happening then you still have a valve timing problem somewhere. Hope this helps. Regards,
Combustor.

[mikenash]

Maybe the cylinder block has been machined too many times eg it is too low

Thanks for your thoughts, Gippslander

Yep, you may be right.  History is unknown

I had thought, since the exhaust valve seemed to be affected but not the intake, and since the engine arrived with a bent exhaust pushrod,  that there might be a problem with that exhaust valve train specifically . . . .

But on further thought if the intake valve begins to open as the piston descends on the intake stroke (as seems sensible?), whereas the exhaust valve is open during the exhaust stroke and maybe begins to close as the piston approaches the top of that stroke, it may be that - relatively speaking - the exhaust valve has more open duration around the top of a stroke that the intake does, so that, if there is a general clearance problem, the intake valve may not be affected whereas the exhaust one might be?

I'll have to think and measure further

Thanks again for your thoughts. 

Cheers, Mike

[dieselgman]

Here is the valve timing diagram... this may help you check your valve clearance issue. I would try doing the valve adjustment at tdc on compression stroke.



dieselgman

[Thob]

When you put the barrel back on and put the straight edge on it, I assume you mean that the gap was between the straight edge and the top of the piston?  Did you have anything clamping the barrel down?  It could be that you are compressing the gaskets at the bottom of the barrel more than you realize when torquing the head bolts and the bump clearance isn't what you expect.  I'd get the lead/solder/plastigage and check the bump clearance before messing with valve clearance and timing.

[mikenash]

When you put the barrel back on and put the straight edge on it, I assume you mean that the gap was between the straight edge and the top of the piston?  Did you have anything clamping the barrel down?  It could be that you are compressing the gaskets at the bottom of the barrel more than you realize when torquing the head bolts and the bump clearance isn't what you expect.  I'd get the lead/solder/plastigage and check the bump clearance before messing with valve clearance and timing.

Hi Thob

Thanks to you and all the other very helpful chaps here - I hadn't expected such a flow of advice and I really appreciate it all

Yes, just a skerrick of daylight between the straight edge and top of the piston.

And, yes, re flattening the gasket, I had thought of that - it seemed to me that the base gasket at about 0.5mm? wouldn't compress enough to use up all the headspace donated by the head gasket at about 2mm ?  Bu that's pretty rough thinking

Yep, plastigauge is next'

Thanks, appreciate the help

Cheers, Mike

[mikenash]

Hi there Mikenash,
                          Am sure there are experts here who can pinpoint your problem, but if you are sure the timing gears are correctly meshed, then time to look elsewhere. The hollow cams are fixed to the camshaft with taper pins. Is it possible that a pin is broken or wrongly fitted ? Time to check valve train timing. First properly locate TDC. Rig a pointer near flywheel timing marks. Pull injector and poke a rod down on the piston.  Rotate crank till rod is say 20mm down on piston before TDC, mark flywheel at the pointer. Then mark again when say 20 mm down after TDC, Measure half way between flywheel marks and this is accurate TDC. Now rotate and watch valves at the junction of intake and exhaust strokes (not compression stroke). Exhaust valve should be just closing and intake about to open right at TDC. If this is not happening then you still have a valve timing problem somewhere. Hope this helps. Regards,
Combustor.

Hi there, combustor

Thanks for your thoughts - a good insight

I had thought, since the exhaust valve seemed to be affected but not the intake, and since the engine arrived with a bent exhaust pushrod,  that there might be a problem with that exhaust valve train specifically . . . .

But on further thought if the intake valve begins to open as the piston descends on the intake stroke (as seems sensible?), whereas the exhaust valve is open during the exhaust stroke and maybe begins to close as the piston approaches the top of that stroke, it may be that - relatively speaking - the exhaust valve has more open duration around the top of a stroke that the intake does, so that, if there is a general clearance problem, the intake valve may not be affected whereas the exhaust one might be?

I'll have to think and measure further

I will get out the vernier caliper or some such and stick that down the hole for a start-off

Thanks.  I appreciate all the advice

Cheers, Mike

[mikenash]

Couldn't be something simple like someone has put the wrong Pushrod in Could it?

Hi there, Glort

I wondered the same thing myself, since it had "allegedly" "been running" with it bent

I have ordered two new pushrods to eliminate that possibility

In the meantime - armed with all the wonderful information from your colleagues - I will measure and think

Thanks, Mike

[mikenash]

Here is the valve timing diagram... this may help you check your valve clearance issue. I would try doing the valve adjustment at tdc on compression stroke.



dieselgman

Hi Dieselgman

Did I say "thanks" for this?  I may have forgotten to do so

Wonderful.  It's just what I needed and what i spent a half-hour this morning googling for unsucessfully

I will mark TDC with care, do that 24 qnd 3/4 inch (actually will measure in MM) diameter to circumference to degrees thing and draw some pictures on the flywheel

Cheers, Mike

[dieselgman]

A large degree wheel can also be helpful, although not strictly necessary. I do like the practical approach that 38ac covers in his write-ups. Look at the WOK section.

dieselgman

[mikenash]

A large degree wheel can also be helpful, although not strictly necessary. I do like the practical approach that 38ac covers in his write-ups. Look at the WOK section.

dieselgman

Okey-dokey.  Thanks, Dieselgman, folks, for all your advice(s), this is what I did

(and excuse me again while I am long-winded, sorry)

Step one - used the vernier-down-the-injector hole to find TDC - rotating the engine in both directions.  The two marks are about 6mm (one degree) apart so that will do.

Step two – my good steel tape says the flywheel is 1906mm in circumference; and George’s Utterpower spec page says the 23.5 inch wheel is 1887mm in circumference.  So that will do.

(1906 divided by 360 = 5.2944mm per degree)

Step three – using your recommended technique (valve opening begins when the pushrod tightens up and valve closing ends when it comes loose again) I marked my actual Intake Open, Intake Closed, Exhaust Open and Exhaust closed on the flywheel with a big black felt pen

(Newbie/idiot comment: Rotation is clockwise if I am facing the flywheel on the injector/oil pump side, and thus, say, the mark for the nominal opening point of the intake valve at 4-8 degrees BTDC is 4-8 degrees CLOCKWISE - ahead -  around the flywheel?)

Your specs say:
Intake Opens 4-8 degrees BTDC say 6 degrees nominal
Intake Closes 14-18 degrees ABDC say 16 degrees
Exhaust opens 42-48 degrees BBDC say 45 degrees
Exhaust closes 6-10 degrees ATDC say 8 degrees

Now, I don’t have a degree wheel but I can measure, calculate and count.  So, if TDC is 0/360 degrees, then:

I.O. nom. 354 degrees?
I.C. nom. 196 degrees?
E.O. nom. 135 degrees?
E.C. nom. 8 degrees?

These are good nominal points if my calculation is OK

Measuring my markings around the flywheel (actuals garnered by the “when the pushrod tightens up/comes loose” method - so not TOO bad probably – gives me these figures below
(not corrected in any way):

I.O. at 105 degrees – 111 degrees ahead of nom at 354
I.C at 308 degrees – 112 degrees ahead of nom at 196
E.O at 273 degrees – 138 degrees ahead of nom at 135
E.C at 95 degrees – 87 degrees ahead of nom at 8

I had previously set the valve clearances at TDC as per advice at 0.017 (my 0.45mm feeler gauge) and 0.032 (my 0.8mm feeler gauge)

They seem like very big gaps but I take on board the wonderful 38ac lecture on valves/lash/timing/breathing . . .

(Just a thought that if my ACTUAL exhaust valve duration is from 273 degrees to 95 degrees – fully open around 6 degrees perhaps, depending on cam profile – no wonder the valve hits the expletive-deleted piston?)

(I haven’t figured a way to copy/paste images onto here, otherwise I would post one showing the line on one tooth of the cam gear nestled between the dots of two teeth of the idler gear)

Looking at the above makes me wonder if my cam train’s timing is maybe 90 degrees out of whack or something similar?

I guess next I’ll pull a main bearing housing off and check the drive gear-to-idler gear marks?

Do I have my thinking right or are there some Newbie Dumb Assumptions being made here?

FWIW I am a 59-year-old engineer who grew up with old pushrod/points/carbs Bedford trucks, and spent a chunk of life repairing sawmill machinery; so while the Lister Diesel is unfamiliar to me, many of the concepts are not . . .

I’m interested/amused that this engine was sold to me as “used to run OK, won’t take much to get it going . . . .”

Once again I appreciate the interest and advice

[EdDee]

Hi MN,

Looks like your cam is indeed around 90 degrees out.... Don't stress, its easy to sort, don't even need to pull off a bearing trumpet... pop off the cylinder (its loose anyway) and pull off the piston, just to get it out the way. Put the crank to around 90 BTDC and loosen the top right bolt of the IP side trumpet... this would loosen the idler gear shaft. Take out the idler gear and check it over for missing teeth and damage while you are at it. If its serviceable, put it back in place and just ignore the timing marks, there is a way easier way to do things.

Now turn the crankshaft to TDC as viewed from above through the "top hole" .... as close as you can judge it. Slip the idler shaft out the idler gear and unmesh it... While looking in the CC door, turn the camshaft and judge the cam followers until they are level with one another, ie intake starting to close, exhaust starting to open.... Pop the idler back into place and your timing should be pretty much spot on. One tooth in either direction gives a BIG change to the position of the crankshaft when the cam followers are level with one another and "on the rock"....

Sometimes, you might have to try and jump the mesh one way or the other by a tooth or so to get things right.... Turn the motor over in the direction of "normal" rotation to confirm your setting, a bit of wear on the gears will give "false" estimates!!

Job Done!

Once this is done, do your IP timing too, it is well worth it!!

Keep it spinning....

Cheers
Ed

PS - A bit of an afterthought....Check your exhaust rocker for damage/bending... If the idler and other gears' teeth are intact, it looks like the last person to PM the unit didn't know about valve timing.... A solid smack on the valve from the piston, might have buckled the rocker too....and...there is no way it could have run as it is now...

[mikenash]

Hi MN,

Looks like your cam is indeed around 90 degrees out.... Don't stress, its easy to sort, don't even need to pull off a bearing trumpet... pop off the cylinder (its loose anyway) and pull off the piston, just to get it out the way. Put the crank to around 90 BTDC and loosen the top right bolt of the IP side trumpet... this would loosen the idler gear shaft. Take out the idler gear and check it over for missing teeth and damage while you are at it. If its serviceable, put it back in place and just ignore the timing marks, there is a way easier way to do things.

Now turn the crankshaft to TDC as viewed from above through the "top hole" .... as close as you can judge it. Slip the idler shaft out the idler gear and unmesh it... While looking in the CC door, turn the camshaft and judge the cam followers until they are level with one another, ie intake starting to close, exhaust starting to open.... Pop the idler back into place and your timing should be pretty much spot on. One tooth in either direction gives a BIG change to the position of the crankshaft when the cam followers are level with one another and "on the rock"....

Sometimes, you might have to try and jump the mesh one way or the other by a tooth or so to get things right.... Turn the motor over in the direction of "normal" rotation to confirm your setting, a bit of wear on the gears will give "false" estimates!!

Job Done!

Once this is done, do your IP timing too, it is well worth it!!

Keep it spinning....

Cheers
Ed

PS - A bit of an afterthought....Check your exhaust rocker for damage/bending... If the idler and other gears' teeth are intact, it looks like the last person to PM the unit didn't know about valve timing.... A solid smack on the valve from the piston, might have buckled the rocker too....and...there is no way it could have run as it is now...

Hi Ed

Thanks

Can't fault that for KISS

I'm just beginning to appreciate the simplicity & elegance of these things

First time I took the gibs & flywheels off it took me an hour of hammering and wedging.  Now with gibs & keyways tidied up and shafts polished and a bit of coppercote it's a two minute job.

I suspect much of the machine is like that

I was going to buy a Lister-clone but decided, eventually, an original one was a better bet, simply in terms of original build quality

I have an ST-clone 5kW unit coming from China for it (a good Stamford one, 20 years old, is still worth $2K here, sadly) and I'm hoping it'll just need maybe bearing/housing work to be a solid, serviceable unit

We'll see how it pans out

Plus I have the wonderfully helpful OldTimer Engines man, Rob, in our big Offshore Island, who seems to have all the parts I'll ever need

Interesting times ahead

Thanks for your input & everyone else'

Cheers, Mike

[mikenash]

Hey Ed

Thanks again for that simple fix.

I had an hour this evening so simply took the front cover off, reached in and popped out the idler, rotated the cam until the followers were rocking and - with a bit of fiddling around the crankshaft - put the cam back in.

Just very quickly it looks as if the inlet cam follower starts to come up maybe 50 or 60mm BTDC around the flywheel - maybe 6 or 8 degrees?  Can't be far off right

Ran out of time to do anything more but it's a five-minute job to change if I have to move it a tooth

Of course with the pump cover off I can see a few more jobs - small flats developing on the roller that follows the governor, what looks like should be a roller on the cam-follower for the oil pump but doesn't seem to go round . . . and so it goes

It's so easy to lever out a gib key and slide a flywheel outwards that they are no barrier to working in those areas at all

Unsiezed the 15/16 head nut on the IP adjustor while I was there so once I have the cam timing right I will enjoy tinkering with the spill timing.  Got an old 24mm ring-and-open-ender here I can cut in half to do that adjustment if space is tight

Thanks again for the advice

Cheers, Mike