Were those figures with the engine hot and the throttle held full open?

The engine was warm but no throttle - should the engine be started as normal but only on 3 cylinders (measuring one) ?

Remove all the plugs, and hold the throttle full open whilst you spin it over at least ten full revolutions.

If the throttle's closed, you're getting an artificial reading because it's "sucking" on the intake against the closed butterfly.

Thanks - understand now.

Will give it another go tomorrow.

Chris,
the 'usual procedure' for a compression test is to have the engine warmed up, all plugs removed and the throttle wide open.
( Because of concerns about damaging plug threads by removing plugs when the cylinder head is hot, I usually slacken them then just nip them up with the engine still cold. Start the engine and run it at a fast tickover to warm it up.)

One step that doesn't seem to be mentioned in many instances is to check and adjust the valve clearances prior to testing.
Given that all valve clearances close up with use, the exhaust valves more so than the inlets, it's pointless carrying out a test on an engine where the valves are not being allowed to seat correctly.

Finally, I have no idea what's going on by specifying the cylinder pressure(s) at 4,000 rpm.
All of the compression tests I've carried out, or read about, have been conducted at engine cranking speed.
For Citroen's A series engines, 150 psi is the target for 8.5:1 engines, 175 psi for 9.0:1 engines, so the question must be "what's the nominal compression ratio for your Simca engine?"...

ken

I cannot find any mention of compression ratio in the book I have - there was only one engine and it states:

Volume d'une chambre : 26 à 27 cm3 en place sur le bloc cylindres

Pression de compression : 10 Kg.-cm2 à 4.000 t.-m

I will redo the test the way you guys have stated and see what happens.

Also what is the correct numbers for the 425cc engine of the AZU?

Ok - being a bit thick here but where is the compression figure - is it 12 bar?

Engine plate: Cc: Type: Car: Date: Comp: Power: Torque: Comment:
SAE DIN rpm Nm rpm
AZU 425 A53 AZU 9/54-2/62 12 10 3500 21 2000

The compression ratio for a 425 engine would have been either 7.5:1 or 7.75:1, depending on its year of manufacture.
It's been a while since I worked on one in good condition, but reckon you should be looking at 120 to 130 psi / maybe 8 to 9 bar...
There's the usual proviso that there should not be more than about 10 psi / 0.7 bar difference between the cylinders.

ken

If anyone knows anyone who wants a little Simca 6 I am selling mine. I need to sell it for funds to do the Traction I was given.

Here it is on Le Bon Coin http://www.leboncoin.fr/voitures/635173056.htm?ca=16_s

Cheers
Ian