Setting Tappets

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tassuperkart
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Setting Tappets

Post by tassuperkart » Sun Oct 21, 2012 7:51 pm

A simple guide to setting tappets.
Tappets are almost universally set HOT altho there is a cold setting for initial setups. Remember, cold set is always just for an initial setup.
ALWAYS perform a subsequent hot set after running the engine to hot operating temp.

The correct clearance will depend on whether the cam is stock or re-ground.

Stock clearance is 0.22mm (0.009") COLD
0.28mm (0.011") HOT on both inlet and exhaust.

Ground cams usually have a different specified HOT clearance and your cam grinder will supply this.
If you dont know what the cam is/who ground it then you can use a HOT setting of 0.010" on the inlet and 0.012" on the exhaust side to get you going.

Now, Unless you are running an uber cam, there is only one crank setting you will need to find, TDC. With the engine hot/warm/operating temp, whip off the rocker cover. Turn the engine by hand to TDC. It will be in one of two possible positions, TDC compression #1 or TDC compression
#4.
If the rockers are loose on cylinder #1, it is TDC compression #1 and you can set:

Inlet and exhaust on cyl #1, plus inlet #2, plus exhaust #3.

If it is TDC compression #4 you can set:

#2 exhaust, #3 inlet, and #4 inlet and exhaust.

1: Just loosen the locknut with with a RINGspanner and wind it about half a turn off while holding the grubscrew in place with a large screwdriver.

Avoid using open ended spanners which are difficult to keep aligned and easily slip off the oily nut unless you are well practised.

2: Inset your feeler guage into the tappet gap between the rocker and the top of the valve stem.
I find it easier if you bend the last 20mm of your feeler guages at about 45 Degrees and feed the guage in from the ends of the motor, not directly in from the sides as this causes the feeler guage to bend over the top of the head casting and tends to give false readings.

Remove the spanner and just turn the screwdriver gently down untill you can feel the tappet trap the feeler guage lightly. Turn the screw back and forth the get a "feel" for this.
Turn the screw down brutally and youll just depress the valve down.
The feeler guage should resist movement snugly but not tight.

3: Leave the feeler guage in position. Just rest it on the valves.
Steady the grubscrew with the screwdriver and tighten the locknut using the RINGspanner end. Dont brutalise this locknut and rip it up like a fucken moronic gorilla! Its only an M8 thread and only needs to be firmly nipped up.
Dont allow the grubscrew to turn when tightening the locknut.

4: Now, check the feeler guage again by sliding it back and forth gently.
there should be some light resistance to pulling the feeler guage thru the tappet gap.
As a rule, when you nip up the locking nut, youll pull the adjusting grubscrew up against its threads and create a couple of thou of extra clearance.

If the guage is too loose OR quite tight and difficult to move then repeat the above steps.
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