Valve clerances

[sprint]

The original manual spec for the valve clearance is 0.05 to 0.1 mm which I understand is now recommended to be set to 0.1 to .15 mm?

What is the reason for the higher recommended clearances and does that not retard the ignition slightly?

With reference to the original manual it show that checking the clearance is done with the cam lobe in its highest position. However, I understand that the clearances are now done by aligning marks on the cam gears with the face of the head so that you can check 1 & 4 and 2 & 3 at the same time but in this case the cam lobes are now more or less to the side.

Is either way OK in terms of measuring the correct valve clearance.

[zed1015]

Measure the clearances with the cam lobe pointing directly away (180 degrees) from the cam bucket so that you a fully on the base circle.
Aim for between 0.10mm and 0.15mm with std cams.
Preferably towards the higher figure.
It is impossible for the cam timing or valve clearance to affect the ignition timing as the ign timing is tied to the crank not the cams.
The wider figures were introduced mainly to reduce the chance of burnt valves, especially the exhausts as 0.05mm is too tight for these and at high temperatures the lower gap can close to zero or minus causing the valves not to seat.

[chrisu]

Measure the clearances with the cam lobe pointing directly away (180 degrees) from the cam bucket so that you a fully on the base circle.
Aim for between 0.10mm and 0.15mm with std cams.
Preferably towards the higher figure.
It is impossible for the cam timing or valve clearance to affect the ignition timing as the ign timing is tied to the crank not the cams.
The wider figures were introduced mainly to reduce the chance of burnt valves, especially the exhausts as 0.05mm is too tight for these and at high temperatures the lower gap can close to zero or minus causing the valves not to seat.

this is the right answer.....

[sprint]

Thanks for the replies.

[ADRIAN H]

Measure the clearances with the cam lobe pointing directly away (180 degrees) from the cam bucket so that you a fully on the base circle.
Aim for between 0.10mm and 0.15mm with std cams.
Preferably towards the higher figure.
It is impossible for the cam timing or valve clearance to affect the ignition timing as the ign timing is tied to the crank not the cams.
The wider figures were introduced mainly to reduce the chance of burnt valves, especially the exhausts as 0.05mm is too tight for these and at high temperatures the lower gap can close to zero or minus causing the valves not to seat.

this is the right answer.....

+1