964 cam timing in '83 SC engine

[ebmbiker]

Hello folks and greetings from the UK.

I've got a pair of 964 cams which are I'm putting in my '83 SC whilst it's being rebuilt.

The bloke doing my engine has rebuilt lots of engines but has never put 964 cams into an SC so he's asked me if I can find out the valve timing values.

Thanks in advance.

JB

[Nux]

1.26

[shamrok]

I’ve done a lot of reading on this and it seems all over the place. 1.26 seems to be common but I’ve seen 1.8 and 1.9 in the forums. Seems the more advanced timing shifts the power band to lower revs, giving it more apparent low end power versus the higher end power with 1.26. I think I’m going to split the difference and do something like 1.6.

[Flat6pac]

With CIS pistons you don’t have that luxury of choosing across a wide range of settings.
I think the recommendation is 1.1 to 1.4 with 1.25 being target.
The last 3.4 I did I got close to 2.0 with JEs 9.8
Bruce

[ebmbiker]

Thanks guys. I’m using CIS pistons so the 1.25/1.26 will be it.

[AndrewCologne]

As Shamrock said, be aware that with 964 cams your engine needs RPMs in the 6k range to benefit from the significant noticable bump of power. On the other hand you will loose significant midrange torque. So its up to you which type of driving you prefer.

You can compensate this loss by choosing the mentioned more advanced setting up to 1.7 mm.
BUT be careful with the final head to piston clearance on every crank degree as the 964 comes with more valve lift! So tensioner washers must be calculated as well.