Following on from a recent thread ... a step by step guide.

TOOLS:
Torque wrench and 12mm socket
12mm spanner
14mm socket and extension bar
Feeler gauges
10mm spanner
Flat bladed screwdriver

Find yourself a tub to catch the oil in. The engine was out when I took these photos, but you can do it very easily with the engine in the car. You'll just need to remove the wings.




Remove the rocker covers (the "jellymoulds") using a 12mm spanner on the domed nut in the middle of each one.




Now you can see the valve gear. At this point (before adjusting the valve clearances), you might want to check that the cylinder heads are torqued down properly. Undo each of the three domed nuts - one at the top of each rocker shaft and one at the bottom centre of the head - by a quarter of a turn or so. Then set your torque wrench to 18 lb/ft and tighten them back up again.




Turn the engine, using the starting handle or a 14mm socket on an extension bar, until the exhaust valve on one side is open. It doesn't matter what order you adjust the valves in, I do the exhaust valves first for ... well, no reason at all, really.



Exhaust valve closed:



Exhaust valve open (ie, spring compressed)



Set your feeler gauges to 0.25mm. Walk round to the other side of the engine (ie, opposite to the valve you've just opened) and stick your feeler gauge in the gap between the rocker arm and the valve stem.





It should be a firm sliding fit. That is, there should be some resistance, but at the same time you should be able to slide the feeler gauge up and down between the valve stem and the rocker arm.

To adjust the clearance, undo the 10mm nut on the other side of the rocker arm from the valve and screw the adjuster in or out, all the while keeping your feeler gauge in the gap. Ideally, you need three hands for this, but it's easier to do than to describe.



Repeat the process for the other three valves. The inlet valves (those are the ones at the rear of the engine) should be set to 0.20mm.

Put your rocker covers back on. Haynes says to torque them to 3-5 lb/ft, but if you do that you'll just squash them until they foul the rockers. Tighten them sensibly, and make sure they don't leak when you fire up the engine. If your rocker cover gaskets were old and hard, renew them; if not, you're probably ok to reuse them.

Comments, corrections and clarifications welcome.

If only Haynes was as good! Beautifully clear. Well done RT

Nicely done Mr RT
btw ....is it a Dyane or Ami engine?

best regards
T.

Dyane - the edge of the fan aperture on the front cowling's different on Ami, because it mates up with the front panel with a rubber bellows.

Nice one.
Valve clearance 0.20 not 0.25

A tappy tappet is a happy tappet.

Old wife's tales
I never set any valves to 0.25 mm. Why go against Citroens specifications

D'you run it on 1970s-spec fuel?

All our A models run on octane 95 lead free, no worries at all. That include 1000's of my customers too. Never have any problems. The main reason for 0.25 mm is to allow more heat to escape through the valve seats but A model engines do not overheat, even down under in 45 degrees with the throttle on the floor for 8 hours.

In recent years I've had to pull more than one head off a late 2CV engine and replace burnt out or leaking valves. And they did it even in the 70s. I distinctly remember breaking down in my mum's 2CV4 on the way to Holland. A traffic policeman bodged it back into life, but it needed new valves before she could cane the poor little thing back to England. Even now she'll berate you for lifting off for roundabouts when taken out in a 2CV; she's convinced you should have your foot mashed hard into the floor board at all times.

Fortunately she doesn't drive her Volvo S80 like that

Personally I'd err towards the loose rather than the tight end of the valve clearance setting.