DIY Valve Clearance for MIVEC

15 January 2005 12am till 2am

Ah Ming (owner of MIVEC) and I didn't had any MIVEC manual to start of with. The only specifications we have are from JUN's performance cam shaft intake clearance of 0.1 mm while exhaust is 0.2 mm.


1st thing 1st.

Don't do this by yourself unless you're really confident and have all the necessary skills, knowledge, know-how and most importantly.... FRIENDS and MORAL SUPPORT.


Part 1 - Open the CAM Cover

Easy :)

Part 2 - Adjust cam pulleys and crank pulley angle to zero

First, jack up the front wheels.

Second engage 5th gear.

Third turn the wheels.

If it has clutch type LSD, then make sure one wheel is locked, else the opposite wheel will turn in opposite direction and the cam and crank will not turn.

Why FF clutch type LSD so mafan (troublesome) one? FR clutch type LSD both turn in same direction, so easy :) hhehehehhehe

Part 3 - Measure valves clearance

But measure where ha?

First we measured the gap between the lobes shown by the green arrow: -

Then we realized it was not logical and finally confirmed it should be between the purple arrows / circles to the valve stem.

So, the measured results are: -

Valves 1 2 3 4 5 6 7 8
Intake 0.15 0.15 0.15 0.15 0.20 0.15 0.15 0.10
Exhaust 0.25 0.25 0.30 0.25 0.25 0.25 0.25 0.225

Very few were out of spec. Since allot are same so we adopt the majority as reference.

Part 4 - Adjust tappet

Releasing the nut and turning the screw was easy on intake 5 and exhaust 3. But it was impossible to release the nut for intake 8 and exhaust 8, because they are blocked by the cam lobe.

See picture below, light blue arrow represent intake 5 and exhaust 3, which is on the left.

Magenta arrow is on the right and clearly shows blocking.

So, Ah Ming was going to give up adjusting the last two tappets, then suddenly I've got a trick and asked him to hold down the other wheel while I turn the cams using one wheel in 5th gear.

The idea is to turn the cam lobe until pushing the valves completely open. i.e.

Now we can clearly see that the nut is accessible and do not need to remove the cams :) hurray :) Hahahaha, this is why for inexperienced enthusiasts without instruction manual need friends and moral support :)

During this time, Ah Ming said it is easier to adjust the screw when it is forced in place by the valve spring, else the screw float and makes locking the nut sensitive. Another experience gained.


Disclaimer - don't come to me to adjust tappets, I only did it for fun and learning experiences.

BTW the timing belt does not need to be released. Why MIVEC so good one?




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