here goes part three:
3.Setting the cam timing
Many cam manufacturers give setting instructions as you have gotten for yours, i.e. degree figures for opening and closing points. Although this surely is the most exact method to define cam timing I find it extremely impractical. I prefer to set the cams according to their lift peak point. A cam with a symmetrical lift profile -as yours presumably is- has its peak exactly between the opening/closing points, in your case at (180+95+50)/2-50=112,5 degrees BTDC, which in my opinion is extremely advanced! This cam should work in conjunction with an equally advanced inlet cam or you will have too little overlap and your engine will not rev too gladly!
But back to work: rotate the engine from its TDC backwards until your pointer marks 112,5 degrees BTDC on the timing disc. This is the position in which the new exhaust cam has its peak i.e. the tappet has travelled farthest up. If your old exhaust cam is still installed, the tappet foot should sit on the cam peak - at least approximately because your old cam will have other timing figures.
In this position, however, you cannot change the cams because the full valve spring load is on them. So you turn the crank one full rotation until it again sits at 112,5 degrees BTDC. Now the exhaust valve is fully closed and you can take out the old cam and put in the new one; put it in as exactly as you can so that the tappet foot sits squarely in the middle of the cams bottom circle. Leave all the other gears in place, just move the exhaust cam in and out on its spindle. Now turn the crank again one full rotation. The exhaust pushrod should be up again at its maximum. Now set your dial gauge on top of the exhaust pushrod and turn the crank around a little to both sides. The dial gauge should read equal figures on both sides of the peak. Take measurements at about 30 degrees both sides from the peak. Are they the same at 142,5 BTDC as at 82,5 BTDC? Congratulations, you are done! But usually you dont hit it first time. If the measurements are not the same then you have to establish your true peak. Lets say your peak lift is 9,65mm and you have equal lift figures of 9,05mm at 140 BTDC and 82 BTDC. Then your true lift peak is at (140+82)/2=111 degrees BTDC. Leave well alone! You wonīt get any nearer! Remember that you can only change the timing of your cam by by engaging its drive gear one tooth apart! And with the cam wheels having 36 teeth one tooth apart means your cam timing will be moved out by 20 degrees crank angle!
So with a non-vernier cam the worst you can be out is 10 degrees crank angle.
Hope this will help a bit. This is the method I have found to work easiest but I am sure there are a lot of people out there who have useful hints to add.
Cheers and good luck
Andy
