also when turning her over it feels very easy
Mini Overheated And Won't Start Again...
Started by
matt_bfc
, Aug 08 2012 11:41 PM
20 replies to this topic
#17
MiniLandy
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One Carb Or Two?
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Posted 23 August 2012 - 04:09 PM
Testing for compression with your thumb isn't enough, buy/borrow a tester.
Check the gaps between the rocker arms and the tops of the valve stems with a feeler gauge, should be 0.3mm when cold.
Check the gaps between the rocker arms and the tops of the valve stems with a feeler gauge, should be 0.3mm when cold.
#18
matt_bfc
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Learner Driver
Posted 23 August 2012 - 06:06 PM
Ok ill buy a compression tester, what would it mean if there is no compression? or if there is? Ill check the gaps, what if they arnt 0.3mm?
cheers
cheers
#19
tiger99
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Posted 23 August 2012 - 06:52 PM
If they are not 0.3 mm (strictly, 12 thou, 0,3 mm is close enough), you adjust them. Use the rule of 9, when valve number 1 is fully open, 9-1=8 so you adjuct number 8. Similarly, if number 3 is open, you adjust number 6 etc.
I do it by loosening off all 8 locknuts a long way, so they are obviously loose, then set them one at a time, tighening the locknuts as I go, so I can see that all 8 have been done. The clearance shifts slightly as you tighten the locknut, but with practice you can allow for that so that it comes right when tight.
I turn the engine by putting it in 4th gear and pulling or pushing as necessary. Ignition off! You can take the spark plugs out to make it easier.
Adjust them and see what happens. The tappets have to be set correctly for a compression test to be meaningful, so you need to check them before the compression test.
I do it by loosening off all 8 locknuts a long way, so they are obviously loose, then set them one at a time, tighening the locknuts as I go, so I can see that all 8 have been done. The clearance shifts slightly as you tighten the locknut, but with practice you can allow for that so that it comes right when tight.
I turn the engine by putting it in 4th gear and pulling or pushing as necessary. Ignition off! You can take the spark plugs out to make it easier.
Adjust them and see what happens. The tappets have to be set correctly for a compression test to be meaningful, so you need to check them before the compression test.
#20
MiniLandy
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One Carb Or Two?
- Location: Ramsey, Cambs.
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Posted 23 August 2012 - 07:43 PM
If they are not 0.3 mm (strictly, 12 thou, 0,3 mm is close enough), you adjust them. Use the rule of 9, when valve number 1 is fully open, 9-1=8 so you adjuct number 8. Similarly, if number 3 is open, you adjust number 6 etc.
I do it by loosening off all 8 locknuts a long way, so they are obviously loose, then set them one at a time, tighening the locknuts as I go, so I can see that all 8 have been done. The clearance shifts slightly as you tighten the locknut, but with practice you can allow for that so that it comes right when tight.
I turn the engine by putting it in 4th gear and pulling or pushing as necessary. Ignition off! You can take the spark plugs out to make it easier.
Adjust them and see what happens. The tappets have to be set correctly for a compression test to be meaningful, so you need to check them before the compression test.
Yup, good stuff this.
One other thing, if the gaps are too large, the engine will sound a bit rattley, if they're too small then you'll lose compression when it warms up. Sooo better to have them slightly too big than too small.
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