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Discussion Starter #1
Does anyone here have some data of the recommended valve spring pressure on C&B cams for the 12v v6 engine?

For instance:
Original is 33kg static and 70kg at 10,0mm valve lift.
Catcams use 36kg at static (34mm spring length) and 101kg at 12mm lift.


I've tried to mail C&B about it, but it seemed like they did not have an answer.
 

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Richard Jemison
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V6 springs

On this motor you have to be cautious about spring pressures due to the exhaust rocker system.

The rocker rate adds a multiplier (1.4x) on the pressures on the small cam lobe and cam follower. High spring rate will destroy the exhaust lobes and followers.
As well the V6-12V springs are both shorter and smaller in diameter than the 4 cyl springs, so you have to be careful what you use. Particularly as C&B uses a larger exh lobe than needed for their intake design.

I use a spring made specifically for these engines due to the nature of the valve system.
If these are cams with lifts under 11.5mm gross I would suggest sticking with NEW factory springs.
These are not designed as high RPM motors (Rocker failures) so stock springs on any milder cam should be fine. If you have bought race type cams then you need to use 2 separate spring designs on intake and exh.
 

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Discussion Starter #3
I have the race medium cam, witch lifts 11,4 on intake and 11,2 on exhaust. I have bought the stiffer springs from IAP. But I need some advice on pressure, so I can se too that it gets right. We make the springs with the pressure we want, I only need some numbers from someone with the experience with this engines and serious tuning.

Rpm wise we hope for 7500 or thereabout if the cams allow it..
164 engine with bigger rockers...
 

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Discussion Starter #4
Status on heads right now.



Had to make some space for the lobes...
 
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