Author Topic: Lister CS Fuel Tappet alignment  (Read 166 times)

sinna42

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Lister CS Fuel Tappet alignment
« on: May 12, 2020, 05:28:46 PM »
This is a bit of an odd one !
During the strip down of my 1952 Lister CS 12/2 I discovered that the bores in the Camshaft Covers for the Fuel Tappets were very badly worn.
Along with this there was wear on the camshaft ends as well.

So to do the job properly the camshaft ends have been skimmed to first clean cut & new undersize bronze bushes made to suit.
For the bores for the Fuel Tappets I'd get a new cast iron bushes made with the correct bore, which is 1" reamed.

Now while boring out for these new cast iron bushes this is where the oddity has been discovered.
See photo attached that shows the setup on a milling machine.
Initially the mounting face & bore for the fuel pump was set up true & square. I thought this would be the true datum & would be in accurate alignment with the camshaft centre line, but no, it isn't !
The governor end camshaft cover was out by a good 0.030" & the other end out by 0.010".
I couldn't think how that could have occurred, but perhaps this alignment didn't actually matter ?
I decided to minimise this error so the new bore will be much better aligned to the camshaft centre line & still be perpendicular to the mounting face for the fuel pump.
See second photo that shows a witness cut where you can see the offset to the original bore.
In practical terms this now means the fuel tappets are not acting on the centre of the fuel pump.

I suppose this is not something that has been observed before but it'd be interesting to hear any comments.

Cheers,
Jim
Lister CS 3/1 1938, Lister CS 3/1 1939, Lister H4 Pump, Coventry Victor AN4 Mk1 1944, Gardner 1L2 1962

listard-jp2

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Re: Lister CS Fuel Tappet alignment
« Reply #1 on: May 13, 2020, 08:31:41 PM »

During the strip down of my 1952 Lister CS 12/2 I discovered that the bores in the Camshaft Covers for the Fuel Tappets were very badly worn.
Along with this there was wear on the camshaft ends as well.


Not at all unusual on an engine that has worked in a dust / grit laden atmosphere for any length of time, seen it numerous times myself (it usually also destroys the cam lobe and roller follower]. To date I have always got round it by fitting a s/h item in better condition. But as my stock of good s/h items dwindles I see a time coming when I will have to do as you have done. 


The governor end camshaft cover was out by a good 0.030" & the other end out by 0.010".
I couldn't think how that could have occurred, but perhaps this alignment didn't actually matter ?
I decided to minimise this error so the new bore will be much better aligned to the camshaft centre line & still be perpendicular to the mounting face for the fuel pump.


Having the luxury of been able to refer to the original Lister CS drawings, I can confirm that this drawing shows the cam follower bore lines up with the centre line of the camshaft.

Either it has worn like this, or you got a 'Friday afternoon special'.

sinna42

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Re: Lister CS Fuel Tappet alignment
« Reply #2 on: May 14, 2020, 09:50:31 AM »
That's really interesting that you say that the drawings show this to be in line.
This is, of course, what I assumed it should be.

I have checked on a very low hours CS 3/1 Camshaft Cover that I have with a bit of 1" diam silver steel through the fuel tappet bore.
This is a good neat fit & it most definitely is NOT in line with the camshaft.
This one is probably out by 0.010".

I reckon that Listers must have decided that this wasn't hugely important & it was adjusted when setting up for machining so that various cast features lined up & were centred better.
The main datum being the bore in the boss for the camshaft bearing - these are all very well centred.
Of course we'll never know for sure !

Cheers,
Jim
Lister CS 3/1 1938, Lister CS 3/1 1939, Lister H4 Pump, Coventry Victor AN4 Mk1 1944, Gardner 1L2 1962

listard-jp2

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Re: Lister CS Fuel Tappet alignment
« Reply #3 on: May 14, 2020, 07:04:49 PM »
For future reference, do you intend to put the hole in the cast iron sleeve (for the cam follower pinch bolt) before or after you press it into the housing. I can see pro's and con's for doing it either way.

sinna42

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Re: Lister CS Fuel Tappet alignment
« Reply #4 on: May 21, 2020, 11:33:00 AM »
Hi,
The cast iron bushes were fitted without the hole & were retained using Loctite 638.
The holes were then drilled and tapped 3/8" BSP through to the bore.

Now the Fuel Tappets are an easy, but good, sliding fit !

Cheers,
Jim
Lister CS 3/1 1938, Lister CS 3/1 1939, Lister H4 Pump, Coventry Victor AN4 Mk1 1944, Gardner 1L2 1962