240 General: New (to me) 1980 Volvo 244

[Laird Scooby]

Originally Posted by Othen

Many thanks - that is an enormously kind offer. The B21 doesn't have any slots in the crank pulley - just those 6 or 8 (I forget) M10 bolts. The idea of welding a 22mm socket to a steel bar and attaching it to a convenient bolt (maybe the PAS) is an excellent one. I'll fashion something like that between now and October.

Alan

PS. What would be handy is a photo of the B230 tool so I can get a rough idea.

The PAS belt could slip Alan so the PAS pump pulley nut probably isn't a good idea.

Can i ask why you envisage having to lock the engine in 4 different positions? Seems i've missed something somewhere?

Originally Posted by Othen

Good morn Clifford,

May I ask what you used to grind down the shims that were slightly too big? I have 3 spares from when I fitted the cam to the new head (4.15, 4.05 and 4.00) - I'm thinking that one or two of the shims are already less than those, so at some time in the future I might need some slimmer shims as the valve seats wear. I'm thinking a paste board with some emery paper glued flat to it might do the job?

Alan

The shims are case hardened Alan. If you accidentally grind through this, you'll leave the soft metal of the shim exposed and it can "bell" out leaving the shim stuck in the bucket with an over-large valve clearance. Worst case scenario you have to have the shim machined out of the bucket.

Cheaper in the long run to just buy the correct shims.

Also using any hand lapping arrangement is likely to leave it not quite as flat/parallel as it needs to be.

[Othen]

Originally Posted by Laird Scooby

The PAS belt could slip Alan so the PAS pump pulley nut probably isn't a good idea.

Can i ask why you envisage having to lock the engine in 4 different positions? Seems i've missed something somewhere?

The shims are case hardened Alan. If you accidentally grind through this, you'll leave the soft metal of the shim exposed and it can "bell" out leaving the shim stuck in the bucket with an over-large valve clearance. Worst case scenario you have to have the shim machined out of the bucket.

Cheaper in the long run to just buy the correct shims.

Also using any hand lapping arrangement is likely to leave it not quite as flat/parallel as it needs to be.

Hi Dave,

Maybe not the PAS fulcrum then, but any nearby bolt hole would do, I'll have a look around and see what is convenient.

Why 4 positions: the leak down tester has to be at or around TDC for each cylinder so the valves are closed (otherwise the air will keep escaping) - the actual position isn't all that critical, as long as it is after the inlet valve has closed on the compression stroke and before the exhaust opens at the bottom of the power stroke. So, 4 positions on the camshaft about 90 degrees apart (180 degrees at the crank).

I've never used a leak down tester, but it looks like a really clever piece of kit for diagnosing any manner of mechanical issues with engines. I'm intrigued to see it working.

Good point about the case hardening Dave - that is one of the reasons I asked Clifford's advice.

I keep a spreadsheet record of the shims fitted to the valves and any changes, so all I need to do is measure the gaps and I can easily work out what thickness shim I need without having to remove it. I can then order the correct one (Knight Engine Services in Northampton are very helpful) and with the special tool I'm going to make - pop it in.

[Laird Scooby]

Originally Posted by Othen

Hi Dave,

Maybe not the PAS fulcrum then, but any nearby bolt hole would do, I'll have a look around and see what is convenient.

Why 4 positions: the leak down tester has to be at or around TDC for each cylinder so the valves are closed (otherwise the air will keep escaping) - the actual position isn't all that critical, as long as it is after the inlet valve has closed on the compression stroke and before the exhaust opens at the bottom of the power stroke. So, 4 positions on the camshaft about 90 degrees apart (180 degrees at the crank).

I've never used a leak down tester, but it looks like a really clever piece of kit for diagnosing any manner of mechanical issues with engines. I'm intrigued to see it working.

Good point about the case hardening Dave - that is one of the reasons I asked Clifford's advice.

I keep a spreadsheet record of the shims fitted to the valves and any changes, so all I need to do is measure the gaps and I can easily work out what thickness shim I need without having to remove it. I can then order the correct one (Knight Engine Services in Northampton are very helpful) and with the special tool I'm going to make - pop it in.

You only need to be able to lock the crank in one of two positions Alan, TDC and BDC. The first (TDC) will be ignition stroke firstly on #1 cylinder and next time it comes round, #4 cylinder.

On BDC (180 deg past TDC) it will be #3 on the first visit and #2 on the second visit.

This is stated on the following assumption : firing order is 1-3-4-2 and you set the first TDC point with the rotor arm point at #1 segment in the distributor.

Remember it's a 4 stroke engine and each stroke is 1/2 revolution of the crankshaft so cylinder #1 will only fire once every 2 revolutions, as will they all just fire ocne every 2 revolutions.

Another point to consider is that using a socket on a crank pulley bolt or similar is likely to undo the bolt while performing a leak-down test. The compressed air is going to try and force the piston down the bore and if the piston is slightly after TDC it will turn the engine in the normal direction, clockwise as viewed from the front. The crank pulley bolt is tightened in the same direction and any resistance offered to the bolt by wedging a breaker bar against the floor is going to offer a counter clockwise force. You see where i'm going with this one.

Granted the forces involved may not be enough to shift some bolts but if memory serves, the smaller bolts on the 240 crank pulley are smaller and have a lower torque setting.

[Bob Meadows]

The older method:~ A sheet of flat glass- fine grinding paste (used for valves) lubricate with oil—get the muscles working & keep measuring. A disk or small item can be part sunken into a piece of wood if you find it easier.
Bob

[Clifford Pope]

Originally Posted by Othen

so all I need to do is measure the gaps and I can easily work out what thickness shim I need without having to remove it.

How do you do that? Surely you need to be able to measure the gap with no shim first, in order to work out what thickness shim you need? Or measure the thickness of the existing shim and add/subtract to order the correct one?

I don't see how just knowing gap is 18 thou when it should be 16 thou tells you what size to order, or am I being thick? (pun)

I didn't grind down the face that the cam rubbed on - obviously the underface doesn't need case hardening because there is no wear at that face, and the load is spread over a large area.
I held the shim in a piece of wood with a slight circular depression, and rubbed with grinding paste on a sheet of glass.

Obviously it's only feasible for a tiny reduction in thickness. Also by swapping them around you can often reduce the number that need adjusting at all.

[Laird Scooby]

Originally Posted by Clifford Pope

How do you do that? Surely you need to be able to measure the gap with no shim first, in order to work out what thickness shim you need? Or measure the thickness of the existing shim and add/subtract to order the correct one?

I don't see how just knowing gap is 18 thou when it should be 16 thou tells you what size to order, or am I being thick? (pun)

Alan has created a spreadsheet and recorded the shim sizes of each valve so he can just measure in future, check his spreadsheet and work it out from there. At least that's what i think he means!

[loki_the_glt]

Originally Posted by Othen

Many thanks - that is an enormously kind offer. The B21 doesn't have any slots in the crank pulley - just those 6 or 8 (I forget) M10 bolts. The idea of welding a 22mm socket to a steel bar and attaching it to a convenient bolt (maybe the PAS) is an excellent one. I'll fashion something like that between now and October.

Alan

PS. What would be handy is a photo of the B230 tool so I can get a rough idea.

I'll get you one with the various dimensions in the next few days - just as soon as I can locate a ruler and some suitable background material.

[Clifford Pope]

Originally Posted by Laird Scooby

Alan has created a spreadsheet and recorded the shim sizes of each valve so he can just measure in future, check his spreadsheet and work it out from there. At least that's what i think he means!

Sorry, I still don't get it. How does knowing the gap tell you what size shim you need to close up the gap to say 16 thou?
You need to be able to measure the thickness x of the present shim, and then order x + 16 - 18 = ?
or else be able to measure the total gap with no shim y and then order y -16 = ?.

[Othen]

Originally Posted by Laird Scooby

You only need to be able to lock the crank in one of two positions Alan, TDC and BDC. The first (TDC) will be ignition stroke firstly on #1 cylinder and next time it comes round, #4 cylinder.

On BDC (180 deg past TDC) it will be #3 on the first visit and #2 on the second visit.

This is stated on the following assumption : firing order is 1-3-4-2 and you set the first TDC point with the rotor arm point at #1 segment in the distributor.

Remember it's a 4 stroke engine and each stroke is 1/2 revolution of the crankshaft so cylinder #1 will only fire once every 2 revolutions, as will they all just fire ocne every 2 revolutions.

Another point to consider is that using a socket on a crank pulley bolt or similar is likely to undo the bolt while performing a leak-down test. The compressed air is going to try and force the piston down the bore and if the piston is slightly after TDC it will turn the engine in the normal direction, clockwise as viewed from the front. The crank pulley bolt is tightened in the same direction and any resistance offered to the bolt by wedging a breaker bar against the floor is going to offer a counter clockwise force. You see where i'm going with this one.

Granted the forces involved may not be enough to shift some bolts but if memory serves, the smaller bolts on the 240 crank pulley are smaller and have a lower torque setting.

I think we only have a semantic difference here Dave. As I said above, 4 different positions on the camshaft at about 90 degree intervals - the two pairs (1/4 and 2/3) will look the same at the crank of course. However one looks at it, the engine has to be fixed at 4 different positions on the camshaft.

I think the best way of running the leak down test will be with the cam cover off so I can see where each pair of valves are and work out TDC from there, also if there are any leakage issues it will become obvious if they are due to rings. If an exhaust valve is leaking I’ll be able to hear it out of the exhaust, and similarly at the inlet manifold if an inlet valve is leaking.

I’m not sure about the leak down test being powerful enough to undo the crank bolt - torque produced by the pressure will be roughly proportional to the sine of the crank angle, so within a few degrees of TDC the torque at the crank bolt will be very small. If it was a problem (and I don’t think it will be, the geometry is too much against it) then a way round it would be to run the test at just before TDC, so the torque would tend to tighten rather than loosen the crank bolt.

I’m quite looking forward to using the leak down instrument, and I don’t think it is going to be all that difficult once I’ve manufactured a tool to lock the crank. I’m not sure I’ll have to use all that much pressure, I should think 50 PSI will be sufficient to identify any leaks - the air molecules are pretty small critters :-)

Alan

[Othen]

Originally Posted by Clifford Pope

How do you do that? Surely you need to be able to measure the gap with no shim first, in order to work out what thickness shim you need? Or measure the thickness of the existing shim and add/subtract to order the correct one?

I don't see how just knowing gap is 18 thou when it should be 16 thou tells you what size to order, or am I being thick? (pun)

I didn't grind down the face that the cam rubbed on - obviously the underface doesn't need case hardening because there is no wear at that face, and the load is spread over a large area.
I held the shim in a piece of wood with a slight circular depression, and rubbed with grinding paste on a sheet of glass.

Obviously it's only feasible for a tiny reduction in thickness. Also by swapping them around you can often reduce the number that need adjusting at all.

Hi Clifford,

I thought I’d mentioned above that when I fitted the cam to the head I measured all the shims and have recorded them on a spreadsheet. If I forgot to mention that then please do accept my apology (I forget so much these days). So, all I have to do is measure each of the 8 clearances and type them into my spreadsheet, which will then work out the shim required.

Perhaps I didn’t explain that well above?

Many thanks for the advice about grinding the shims, I think Bob had suggested a similar method previously. I managed to swap round 5 of the shims to bring their valves within tolerance when when I fitted the cam to the remanufactured head, but had to acquire 3 thinner ones where I couldn’t make the maths work out (hence me having 3 spares in my box of bits never to be thrown away.

Alan