Timing chain

[Pavel]

Hi R4-friends,
I noted, R 4 used two timing chain types: simplex and duplex. Have you any idea, how to identify what chain type is used on my 850 cc engine? Without dismounting the engine, of course There are a little bit close quarters between the engine and the car body, there aren´t?
Greetings from Prague Pavel

 

[malcolm]

I have no idea. Post your engine number - maybe someone will be able to figure it out from there.

 

[Pavel]

Unfortunately there is not the engine in accordance to its number, because a previous owner changed the engine but he fitted the old number sheet on the new engine.

 

[angel]

I checked your engine photos and it seems to be the "late" engine so single timing chain. Except if the previous owner fitted all ancillaries, cylinder head etc. to an early (68-69) duplex block(!!!)

 

[Pavel]

I suppose, that the previous owner changed the complete engine. However I´m surprised, that Renault fitted on later models a weaker timing chain. So if I would like come back to the duplex, I should used an older cylinder block?
Pavel

 

[angel]

The different parts are the timing cover and maybe the plate behind it. But the hard part would be to find the duplex chain and gears as this model was produced for one year.
There is absolutely no problem with the single timing chain.

 

[Pavel]

Franzose has the duplex chain in store, however I don´t know, if the sprocket are available. I thought, that the duplex should be better, if I want boost. Analogous to Mini Cooper.

 

[angel]

The Mini is another story...they are fitting duplex chains on them because they don't have a chain tensioner, and the duplex wears slower,among others.
Timing chain has nothing to do with more power...the only reason would be if you wanted to fit extra stiff valve springs...but then why would you want to do so, if you don't intend to modify the R4 engine to be revved high?