5 GT Turbo C1j cylinder liner protrusion measurement clamped and unclamped, what are your specs and what gasket do you prefer?

[SouthendBen]

What are your specs, and what reasons

 

[DaveL485]

@sparkie or @Brigsy will know this. I think mine was 0.10 clamped, though that might have been the last 21 engine I did, thinking about it!

 

[Brigsy]

No clamp as per workshop manual.

 

[SouthendBen]

Thanks for your reply. Yes without clamps in my opinion too, as manual states. Many do run a 010 clearance for extra seal ive read. Liners staggered from highest to lowest within 002 or machined for equal protrusion all round. Interesting to see what others run in comparison and what type gasket. Ive always used a Payen myself

 

[Steve Swan]

If you are using a composite type gasket (original type) then you want more than 2 thou. I tend to use 6 thou when building from scratch with new liners. Make sure they are graduated if there are any discrepancies as the drawing above shows. If you are using a solid metal type gasket then 2 thou is more like the maximum. They are usually not to bad as they are metal to metal with the O ring in the chamfer to provide the water seal. A little bit more nip helps to keep the firing rings sealed.
40 thou to 1mm for reference.

 

[Brigsy]

Ive not heard of anybody running more than stock protrusion for extra sealing on a c1j to be fair. Ive had no issues running inbetween the book protrusions with a normal gasket, im sure mine was around 0.08mm on highest, decent old corteco mellior and 27psi boost.

Not sure what payen are like currently but i recall the quality had slipped a few years ago. C1j gasket is a minefield however loads of poor ones about now.

 

[SouthendBen]

Cool, thankyou for your input il check that HG out

 

[Steve Swan]

There was a fantastic article years ago, which was a rewrite of Ian Schwartz's article by Carvel Webb on preparing Race Gordini Motors and The Wedge head which was the forerunner of the C1J , and in some cases just as powerful and more reliable than the G motor.
In it he advised metal to metal contact at the block base, which the early motors didn't have, but the C1J does, he also reckoned 6 thou protrusion, which I have always run on all my race motors, without ever having head gasket issues and using cheap standard gaskets.
By the time the C1j came along, Renault had got it all worked out and they usually don't give any problems, but I would always advise a dry build to check the protrusions and graduate them as per the manual above.
You could write a textbook on the subject of liner protrusions, some elderly Renaults can be problematic and in Rover's case with the K series they got it wrong big time.

 

[SouthendBen]

Thankyou, i have read that article too. Suggested metal to metal with sealant. Yes i think protrusion is a worthy thread. With so many user variations. I find it interesting to see what others have specced Thankyou for the addition to the thread

 

[sparkie]

Back in the day some of us just slapped the liners in any old way, as long as the gaps between the liners were straight, the rubber seal was in the right position, the block wasn't massively pitted where the liner sits and enough sealant was used, then you didn't get a problem. 70Nm on the head bolts too.

 

[Steve Swan]

I use 12.9 grade bolts on the Head and Main caps. Torqued up to 60 lbs/ ft. That's about the limit for the Block material and thread form. As the Crossflow head is quite deep, it's not a cheap option, but a significant upgrade on the 10.9 originals. There is probably a stretch bolt that would be suitable and provide a better clamp load over the temp range an Engine works through, as it's designed to keep the fastener in it's elastic deformation range. Modern Tech and all that..

 

[SouthendBen]

Thankyou. I find it an anxious moment when having to torque those allen headed bolts, always a relief when completed.
And lol sparkie, luckily the build design and specs were forgiving enough to allow a bit more fun until the next head gasket, or turbo goes pop. Everything was fixed within a few hours roadside back then somehow

 

[Brigsy]

When i started checking tolerances on a c1j i realised how shit they really are even from factory

The 12.9 cap head bolts are sound though, can flog them down no drama. Ive reused my current 12.9 bolts a few times.

The stretch to yeild head bolts in modern engines feel like they are literally going to snap when your angle torquing. Not a fan but it is what it is.

 

[DaveL485]

The 12.9 cap head bolts are sound though, can flog them down no drama. Ive reused my current 12.9 bolts a few times.

At least the block is cast, and a bit stronger. The block on a 21 is alloy and the head bolts last stage is 70lb/ft - 95nm - always makes me cringe a bit when i'm waiting for that last "click" on the torque wrench lol