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Old 11-11-2025, 08:33 PM   #2
Eaton PSI
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The numbers on the shim are the size in mm. So the 194 is a 1.94mm shim. The actual size needed is a bit trickier due to the rocker ratio making the clearance different. There is a formula in the service manual to calculate the correct shim size.
There are 2 different rocker designs. Early engines have valves about 5mm shorter than later engines which require a different rocker. They are not interchangeable, the difference is to much.
It is possible to shorten the rocker pivots to create more clearance. This is best avoided unless you know exactly what you're doing! If your heads are unmodified shims should be available to get it right.
It is also possible to machine the top of the shims to get some more clearance. Again, not recommended but if you know what you're doing and you're desperate it can get you out of a bind.
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