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Discussion Starter #1
Hi All
If the valve end of your rockers is slightly concave from wear it will be difficult to use a feeler gauge to get the clearance correct. I am sure someone has thought of this before but here goes:
The adjusting thread is M8 x 1, so one full turn = 1mm of travel.
We want 0.35mm, so this would be .35 of a turn. The rocker shaft axis is 25mm from the pushrod end, and 40mm from the valve end, so we only need (25x0.35)/40, which turns out to be 0.21 of a turn - a fifth of a turn.
So for the valve being adjusted:
  • Back off the lock nut
  • tighten the adjusting screw down finger-tip tight only, i.e. to the zero clearance position
  • Back off the adjusting screw one-fifth of a turn
  • tighten the lock nut, taking care that the adjusting screw does not move.
This method also happens to be much faster than mucking around with feeler gauges. It may not be as accurate, but I think it would put everything well within acceptable ranges.
Can anyone see why this would not work?
The next time I do this I will have a specially marked screwdriver and drilled plate so I know I am getting exactly 0.21 of a turn.
 

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Glasshouse Bogan #1
nissan patrol gu
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The later td42 rockers are a different design and don't wear.
It was the early silvertops with the issue.
 

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nissan patrol GQ
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The later td42 rockers are a different design and don't wear.
It was the early silvertops with the issue.
is the roller rocker assembly interchangeable?

seems like a smarter upgrade if thats the case
 

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Glasshouse Bogan #1
nissan patrol gu
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There not actually rollers just a wide convex pad rather than a little flat pad that wears.
 

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I'm not a mechanic and it may seem faster but it's not very accurate how do you know the threads aren't stretched on the adjusting screws when the motor has a bit of age on it and quite often the adjusting screw moves just a slight amount in either direction when you tighten the locking nut so you have to undo it and try again. If you have gone to the trouble to pull the tappet cover off you might as well do a proper job of it I'll stick to using a feeler gauge there easy to use at least you won't accidently overdo it by guessing and having some tight and some loose and possibly cause damage when you crank it over. Sorry but this just sounds so dodgy to me if you want your motor to last unless it's just an old bush basher but I still would use a feeler gauge.
 

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I'll stick to using a feeler gauge
The issue being discussed is when the rockers are worn such that they are concave and thus the feeler gauge method doesn't work properly.
I have been through this 10 years ago and I agree the method mentioned by Pter or a dial gauge is what you have to do until you get new rockers or fix them somehow.
This method is used by some people with motorbikes.
 

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Discussion Starter #10
This is all the excuse I need to buy a dial gauge. I can use it to check brake rotor run-out too.
Can I buy a new rocker assembly, or do I have to get the old ones refaced?
 
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