Post by pauldaf44 on Feb 2, 2014 19:29:47 GMT
The following guide is for engines with 2 valves per cylinder.
First we need to know which rule we are going to use the simplest way is to count the number of cylinders, double it and then add one. So for a two pot like in air-cooled DAFS its the rule of 5 and for a 4 pot water boiler DAF you would follow the rule of 9. From this moment on I'm going to assume your following the rule of 9 but the principle is the same for rule of 5, 13 and 17.
How to decipher the rule
The rule of 9 means such. If valve 1 is down adjust valve 8, if valve 4 is down adjust valve 5. Basically when a valve is fully open you adjust the open valve that would add up to 9.
To use the rule
Read your manual some cars need the clearances set with a warm engine but most will want it done with a cold one. Your manual will also tell you what the clearance should be. For DAFs our admin has helpfully put this data in the tuning tab on the right side of the page.
1. Remove the rocker cover/s
2. Turn the engine by hand with the ignition OFF until number 1 valve is fully open.
3. Now you can adjust valve 8. Slacken the lock nut directly above the pushrod with a ring spanner. You can use an open ended but a socket a ratchet cant be used here i'm afraid.
4. Insert your relevant feeler gauge between the rocker and valve stem. Keep it as flat as possible so as to get a true reading
5. Whilst holding the lock nut adjust the adjuster, normally a flat head screw, until the feeler gauge can be slid with slight resistance.
6. Hold the adjuster still and re tighten the locknut.
7. Re-check with your feeler gauge.
8. Look for any other valve that is fully open and adjust another using the rule of 9.
9. Turn the engine so that a valve that was previously open is now shut and adjust the relavant valves
10. Refit rocker cover and enjoy a smoother running engine.
First we need to know which rule we are going to use the simplest way is to count the number of cylinders, double it and then add one. So for a two pot like in air-cooled DAFS its the rule of 5 and for a 4 pot water boiler DAF you would follow the rule of 9. From this moment on I'm going to assume your following the rule of 9 but the principle is the same for rule of 5, 13 and 17.
How to decipher the rule
The rule of 9 means such. If valve 1 is down adjust valve 8, if valve 4 is down adjust valve 5. Basically when a valve is fully open you adjust the open valve that would add up to 9.
To use the rule
Read your manual some cars need the clearances set with a warm engine but most will want it done with a cold one. Your manual will also tell you what the clearance should be. For DAFs our admin has helpfully put this data in the tuning tab on the right side of the page.
1. Remove the rocker cover/s
2. Turn the engine by hand with the ignition OFF until number 1 valve is fully open.
3. Now you can adjust valve 8. Slacken the lock nut directly above the pushrod with a ring spanner. You can use an open ended but a socket a ratchet cant be used here i'm afraid.
4. Insert your relevant feeler gauge between the rocker and valve stem. Keep it as flat as possible so as to get a true reading
5. Whilst holding the lock nut adjust the adjuster, normally a flat head screw, until the feeler gauge can be slid with slight resistance.
6. Hold the adjuster still and re tighten the locknut.
7. Re-check with your feeler gauge.
8. Look for any other valve that is fully open and adjust another using the rule of 9.
9. Turn the engine so that a valve that was previously open is now shut and adjust the relavant valves
10. Refit rocker cover and enjoy a smoother running engine.
