Establishing static advance requirement
The static advance requirement for a modified engine is very much dependent on the duration of the cam fitted. Below is a table of advance requirements and expected idle speeds for a range of cam specifications. ON NO ACCOUNT use these settings before the maximum advance on the distributor has been correctly limited.

Cam duration-----Idle speed expected------------------Advance
----270------------------600-800----------------------------10-12
----280------------------900-1000---------------------------12-14
----290------------------1000-1100-------------------------14-16
----300------------------1100-1200-------------------------16-18
----310+----------------1100-1400-------------------------18-20

When establishing static advance the golden rule is never use less than 10; never use more than 20 degrees. The engine may well tolerate more than 20 degrees at idle, but the moment the throttle is opened and cylinder filling is improved it will ping heavily. One problem often encountered when using more static advance than standard is that the engine may 'kick-back' when starting causing the starter to slow dramatically, this can be confused with a flattened battery or worn starter motor. You may need to compromise by the odd degree or two if your engine will not tolerate the required degrees of advance at start-up.
Static advance implies a measurement taken when the engine is stationery, however it is usually set at idle in order that any latency in the distributor drive gear is taken up. A rough setting can be made when the engine is still, but it MUST be set at 1300RPM or lower with the vacuum advance disconnected so that any latency is taken up and the centrifugal advance has not yet started its operation.

Establishing mechanical advance requirement
We have our desired static and maximum advance figures already calculated, so now we can use the same simple formula to establish how much centrifugal advance we need from the distributor.
Example:
Maximum advance 38 degrees, required static advance 18 degrees (38-18) = 20 degrees required.
In our example the standard distributor is designed to give maximum advance from a starting point of say 10 degrees of static advance, if the maximum advance required is 38 degrees, then it's range is 28 degrees (38-10), this means that if the static setting is increased to 18 degrees, then the total advance will be 46 degrees (18+28), way too much. It is unlikely that the standard distributor will give the correct amount of advance, it will usually give too much. This is why we must restrict the total centrifugal advance that the distributor is capable of supplying to our new figure, in this case 20 degrees, then with the static setting of 18 degrees, the maximum advance will be 38 degrees (18+20), the correct figure.
If the advance supplied is MORE than required, and this is highly likely, it means as expected that the distributor is supplying too much mechanical advance, and that the stops in the distributor must be bent to restrict the travel of the mechanism. If the advance supplied is LESS than required which is unusual, then the distributor is supplying too little mechanical advance and the stops must be filed to allow more travel of the advance mechanism.

its stock compression 9.5 to 1 and the cam is a 268h or 270h the guy i bought it from couldnt remember but he thinks 268h