Measuring Morini Cam Question ?

[smotorboy]

Hello All,

Question: do the duration events with Morini cams begin and end when the valves are .5 mm open?

Looking at my early data, it would be the point that is closest to the published data I have.

Robert in California

[George 350]

Hi,
All the manuals and handbooks I have seen (for the 350's at least) state the timing as with 1mm valve lift. Is definately correct for my '78 Sport. Might be different for later models as I don't tend to look at them too closely, but why would they change an established practice?

George.

[mgill]

With the cam in v blocks or rollers on the bench,
start with 1mm clearance to dial indicator.

[EVguru]

All the manuals and handbooks I have seen (for the 350's at least) state the timing as with 1mm valve lift.

Actually it says to use 1mm valve clearance when checking the cam timing, which isn't quite the same.

(Some people who can't understand english take this to mean the running valve clearance should be 1mm.)

If you were checking the cam in a test stand you'd have to take the rocker ratio into account.

[smotorboy]

A great big " Thank You" for the helpful confirmation of the 1 mm clearance when checking the cam....

As my K-2 is so much newer than the 70's Service Manual info, it is good to be sure...

I now am 99% sure that my motor has an "O" cam grind with 5.60mm lift ....

It is not an "M" cam as most K2's are reported to have....

This goes a long way into explaining the high rpm asthma this motor has exhibited.

I will check the degrees on the L-5 regrind I have later today ...

Robert in California

[smotorboy]

I must correct myself....

After looking at my data and the rocker assy ratio that I was using to figure out when the clearance would be at 1mm, I have decided that I can't be sure of just what the true cam durations are without the entire system being assembled....

So, I'm not sure what cams I have,,, but I do know that the regrind cam I acquired has more intake lift and more intake and exhaust duration that the cam that came in the motor....

[smotorboy]

For those interested, as it turns out I have an "S" cam in my motor and the regrind is an "L".

As I suspected, one cannot correctly measure the lobe events on the bench without knowing the amount of extra duration created by the width of the tappets.

Dry fitted the cams into the cases and measured off the tappets and now the numbers check out.

I suspect my power peak at 7800 rpm with the "S" cam was due to the cam being timed a few degrees advanced from the nominal setting....

Robert

[EVguru]

As I suspected, one cannot correctly measure the lobe events on the bench without knowing the amount of extra duration created by the width of the tappets.

And the extra lift created by the radius on the tappet too.

Have a look at http://performancetrends.com/cam_test_stand.htm

You can download a trial version and manual enter figures. It has an option of calculate tappet lift from raw cam data.