Hi all, just purchased a sport for the winter as the cabs just got painted and would rather leave it in the garage till summer comes round again. Anyway the engine sounds a bit tappety and i've been told to adjust rockers out. Anyone confirm the clearance when hot/cold. 10/10 10/8.?
Any advice appreciated. Thanks
Noisey rockers
Moderator: martauto
-
Templ8e30
- E30 Zone Addict
- Posts: 2801
- Joined: Mon Jan 10, 2005 11:00 pm
- Location: Ashton-under-Lyne, Lancashire
It's a sport so must be an M20, 0.25mm cold / 0.30mm hot.
Cheers,
Iain T
Cheers,
Iain T
2007 Mazda 6 2.0 estate
Political Correctness - A concept based on the idea that its possible to pick up a turd by the clean end !
BAHH and i thought this thread was about the rolling stones!
im so sexy justin brought me back 5 times
whats that about Simon, Just ask for spray bar and the guys at the dealer will know what I'm on about, How's it work mate?Simon13 wrote:if it's still a bit noisy get a new spray bar Ԛ£10 from the dealer, made good difference to one of mine before
-
Turbo-Brown
- Boost Junkie
- Posts: 4705
- Joined: Tue Feb 15, 2005 11:00 pm
- Location: Aldershot, Hants
- Contact:
Never understood why the hot adjustment value is higher than the cold!
Metals (and indeed most engineering materials) expand when hot, that's why we have the valve clearances: so when the stems and whatnot have expanded due to heat, the valves can still close.
So why on earth is the hot adjustment value not less than the cold?!
Metals (and indeed most engineering materials) expand when hot, that's why we have the valve clearances: so when the stems and whatnot have expanded due to heat, the valves can still close.
So why on earth is the hot adjustment value not less than the cold?!
)-
Simon13
- The longest resto in the world !
- Posts: 22697
- Joined: Mon Jan 10, 2005 11:00 pm
- Location: Camberley, Surrey don't u know
i would say because if u set them too tight eg .20 when hot they would be way too tight when the engine is cold and this is not good and when rockers snap
it could of course be smaller than .20 when cold get me!?
it could of course be smaller than .20 when cold get me!?
-
Turbo-Brown
- Boost Junkie
- Posts: 4705
- Joined: Tue Feb 15, 2005 11:00 pm
- Location: Aldershot, Hants
- Contact:
No, it's the other way around by my reckoning.
The gap is there, say 0.2mm when cold to allow the stems to expand and close up the gap as the engine gets hot.
Lets say that you set your clearances with the engine cold to 0.2mm and then went for a drive. If you whipped the rocker cover off and measured the clearances, they should be practically non-existant as the bits of metal have expanded into the clearance.
Now lets say that with the engine hot, you set the clearances to 0.3mm and then left it over night to cool off. If you checked them in the morning, they should be around 0.5mm!
I know I'm ignoring the expansion of the head here, but that doesn't get as hot as say an exhaust valve, although ali does expand more per degree than steel.
Can anyone else see my confuzzlement?
The gap is there, say 0.2mm when cold to allow the stems to expand and close up the gap as the engine gets hot.
Lets say that you set your clearances with the engine cold to 0.2mm and then went for a drive. If you whipped the rocker cover off and measured the clearances, they should be practically non-existant as the bits of metal have expanded into the clearance.
Now lets say that with the engine hot, you set the clearances to 0.3mm and then left it over night to cool off. If you checked them in the morning, they should be around 0.5mm!
I know I'm ignoring the expansion of the head here, but that doesn't get as hot as say an exhaust valve, although ali does expand more per degree than steel.
Can anyone else see my confuzzlement?
-
Simon13
- The longest resto in the world !
- Posts: 22697
- Joined: Mon Jan 10, 2005 11:00 pm
- Location: Camberley, Surrey don't u know
i can see what your saying but by my logic setting them bigger makes sense to me. So when the engine is cool they are still with in tolerance. Maybe the engine expands in a different way to your theory?!
-
Turbo-Brown
- Boost Junkie
- Posts: 4705
- Joined: Tue Feb 15, 2005 11:00 pm
- Location: Aldershot, Hants
- Contact:
Guess it must do!
You're quite right that the books say to set them larger for hot, just strikes me as being arse about face that's all.
Shame they're such a pain to get at on mine, would be an interesting experiment.
You're quite right that the books say to set them larger for hot, just strikes me as being arse about face that's all.
Shame they're such a pain to get at on mine, would be an interesting experiment.
I may be wrong but are these settings not to make sure your valves open the correct amount, So if hot and expanded if you set them same as cold your valve would be opened further than spec.
So your hot size is a larger gap so that when metal items expand the valv e only opens correct amount.
So your hot size is a larger gap so that when metal items expand the valv e only opens correct amount.