21 Turbo J7R 752 cylinder head tightening torque

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Hi.
I'm trying to understand correct cylinder head bolt tightening torque for J7R 752 R21 Turbo 1988.
Dialogys shows 87.5-97.5 Nm for all engines.
Instruction for cylinder head gasket - pre-tightening 20 Nm, than 120°+120°+20°.
Where is the truth?

 

[DaveL485]

Where is the truth?

The original instructions were a 3-stage torque setting + retorque after a heat cycle.

Renault later updated to angle tighten instructions.

I have always stuck to the earlier way, and never had issues. Start at the middle bolt, inlet side, tighten to 36lb/ft then move across to the exhaust side bolt, then spiral outwards all to 36. Repeat the pattern with 58lb/ft. then repeat again with 70lb/ft.
Run the engine to fan temp, allow to cool for > 2 hours then one by one (same pattern) fully release then immediately retighten the bolt to 70lb/ft. Then set the valve clearances. DO NOT release all the bolts then retighten, you have to loosen one bolt and immediately retighten it to 70lb/ft.

 

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After second dismounting and testing was found microcrack in cylinderhead.

 

[DaveL485]

Oh no, thats not good!

 

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As I understand head from non-turbo engine will not fit?

 

[DaveL485]

As I understand head from non-turbo engine will not fit?

The Turbo valves and valve guides are different, the camshaft is different, the combustion chamber shape *might* be different you would need to check.

You could probably use one if you needed to with a Turbo cam, valves and valve guides. It would need to be off a 2.0efi model as the card engines didnt have the cutouts for the injectors and also check the casting shape as there were many types of J-Series heads in different cars, for example the 2.0TXi head in a R21 is a different casting to the TXi Safrane around the thermostat housing.