Page N 9 in service manual shows the adjustment.But it is just a mechanical stop that is moved to allow throttle to move to slow idle or raise idle. Here is link to 4-107 manual.----http://www.bluemoment.com/manuals/Perkins-4.107_4.108_4.99-WorkshopManual.pdf
Thanks for this help and thanks for the down load of the service manual. Could you also send me a copy of the service manual for the Z Drive.
Its an Enfield Z Drive with a dog tooth clutch
Here is one.-----http://myweb.tiscali.co.uk/davenrich/Assets/ENFIELD%20Z-DRIVE.pdf