Camshaft Timings 82 3.0 SC US Spec

[michelko]

Hi folks,
looking for some wisdom about the influnce of the cam timing.
The Specs say Intake Valve stroke with 0.1 play shoulb be between 1.4-1.7mm.
What should i expect from an setting slightly above this numbers.
While doing the Valve Adjustment i checked anf found valve stroke of 1.75 at overlap instead of the 1.4 to 1.7
After a pro did the rebuild the engine didnt feels like before the rebuild.

Regards Michael

[proporsche]

Michael when you said"After a pro did the rebuild the engine does not feel like before the rebuild".
Is it better after rebuild or not better is the Q?

Ivan

[michelko]

Ivan, its hard to say, but it feels a little rougher on idle and i am missing that punch above 3500rpm on accelerating.
It starts good and runs. no unusual oil consumption, no smoke. But i miss that feeling i had before the rebuild.
Ignition and CIS are checked, no issues here.

Michael

[walt]

If this is a 930/10 engine shouldn't the factory cam timing be .9-1.1 mm? I know many including myself usually look to advance this some.

[proporsche]

That is what i expect you say...If you set up the cam timing lower at 1,4 ..i will not have the torque right at 1000 rpm ..but it would have that kick you are missing.With 1,7 ,it has the kick from 1000 and up all the same feeling.....i hope it make sense to you, this explanation
Ivan

[michelko]

o.k. i forgot to say it is an standard 930.16

[targa72e]

Many years ago I played around quite a bit with cam timing. Engine is early big port with headers and 9:3 to 1 pistons and CIS. The dyno chart below shows the same engine with cam timing at the most retarded and most advanced position (also a little more timing in advanced position). The retarded spec does feel faster as the slope as power comes on is steeper. The most advanced position makes more power and torque and will be faster but does not feel faster. because you are just starting with more. This is the reason you cant trust the butt dyno to decide if a change is making more power.



I am not sure if your change will be as big with the later small port heads.

John

[AndrewCologne]

Originally Posted by michelko

Hi folks,
looking for some wisdom about the influnce of the cam timing.
The Specs say Intake Valve stroke with 0.1 play shoulb be between 1.4-1.7mm.
What should i expect from an setting slightly above this numbers.
While doing the Valve Adjustment i checked anf found valve stroke of 1.75 at overlap instead of the 1.4 to 1.7
After a pro did the rebuild the engine didnt feels like before the rebuild.

Regards Michael

Setting the cam timing advance on a 930.16 with original 9.3:1 pistons and original cam profile should not be beyond 1.7 mm as the risk of not enough head to valve clearance will be the result.

Rule of Tumb:
- if you like more power on higher revs then retard the timing to 0.9-1.1mm, but you need to rev the engine more to feel the benefit of the power.
- If you like more torque and power at mid revs then keep the advanced timing at 1.4-1.7

[Daugaard]

I have always looked for 1.2 - 1.4 which 3.2 runs with as recommended in Bruce Anderson's book.