Crank and Camshaft removal

[MsRose]

Good morning all.

Some of you may have seen my restoration thread. Muriel's engine is seized (it's a 948) and I'm in the middle of stripping it. I'm no mechanic and so I'm slow and having to ask for advice, but I'm learning! Please note that it's important for me to do this and learn about the car, rather than people telling me to get someone experienced to sort it.

I'm down to the bottom end of the engine now and need to remove the crankshaft and camshaft and I just wanted to know if there is anything I need to consider when removing? Do I need to keep anything in line? Anything in a certain order etc?

The pistons won't move and so I've left the bores with penetrating oil in, ready to start work tomorrow. If the pistons still won't move should I persuade them with a small block of wood and a mallet?

All advice gratefully received

[philthehill]

When removing the crankshaft ensure that the connecting rod caps are refitted to the right connecting rod and the right way round.
I would centre pop the caps and rods with the number of centre pops re the number of rod/cap before dismantling.
The rods are off set on the crankshaft so need to be reassembled the right way round and in the same place. The centre pops will help.
Do the same with the main caps though they are more easily identifiable.
You can knock the top of the piston with a piece of wood placed between the mallet.
To remove the camshaft you need to remove the distributer drive. I would worry about the lining up of the camshaft as regards both alignment and timing marks when you come to reassemble the engine.

[MsRose]

Thank you philthehill, very grateful for the advice.

[oliver90owner]

In addition to PTH’s reply, the customary/conventional marking of the rods and caps is to dot them on the camshaft side. The camshaft can be considered the “brain” of the engine.

[rocco]

Do you still have to take care of caps location if you fit a new crankshaft and bearings?

[philthehill]

Yes, yes and more yes
You have to because the caps are machined/fitted to the the respective connecting rod.
You cannot just fit the caps to any connecting rod and hope that it will work - because if you do it will fail.

[rocco]

Thanks for the reply. From that I learn that when the caps where made, and I think there are probably millions of them, they were not made with any precision? If they can't be swapped around then there must be some big differences between them, right?

[les]

It’s my understanding that caps were fitted to rods and machined as one unit making the cap unique to that rod. The difference needn’t be big to make cap interchangeably a no no.

[philthehill]

The cap and the rod are assembled and then machined as one unit. Whilst the machining is accurate there will always be differences
so it is best to keep the cap and the rod as a matched pair. The rods and caps are handed so you should not fit a R/H cap to a L/H rod. If you mix and not match you may find that the engine will not turn over because the caps are jamming against the web of the crankshaft. The rods should be fitted the right way round as per ex factory as they could foul the camshaft or block.
My advice is to put everything back as it was found prior to dismantling.

[rocco]

Brilliant, thank you gentlemen. Most helpful. I just hope I can figure out which cap goes with which rod or I suppose I'll need to buy new ones.

[philthehill]

You will have to buy new or used complete rods as big end caps are not available because the con rods/cap are machined sets.

[oliver90owner]

Do check the rods and caps to see if they have been marked previously.