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Help me out on this one
Posted: Fri Apr 17, 2009 11:45 pm
by Peetee
It's late and I'm addled but I want to get this typed out as a concept as it might be worthy as a sticky.
I'm thinking about setting the valve clearances and how finding the fully closed position is a bit hit and miss.
In theory the valves should be closed at a specific point in relation to TDC - or the position of the crank. By marking these position on the crank pully - as is done for the timing you would have an exact reference to work from that could, by removal of the plugs and selecting neutral, be positioned accurately to allow for perfect setting of the valve gaps.
Yes No?
Posted: Fri Apr 17, 2009 11:58 pm
by bmcecosse
It doesn't matter whether the valve is 'fully closed' or not - the follower sits on the back of the cam for quite a distance - and the valve is closed for ages - which is all that matters. The best way is to have the opposite number in the rule of 9 fully open, but again it's not too important that it be 'exactly' fully open - visual check will be fine !
Posted: Sat Apr 18, 2009 12:54 am
by mike.perry
1 open 8 closed
2 open 7 closed etc.
You don't have to do it in order, just turn the engine over on the handle (plugs out), watch which valve is closing and set the opposite one. Mark the valves with a bit of chalk as you do them. It saves a lot of turns of the handle
Posted: Sat Apr 18, 2009 8:54 am
by Peetee
Fair enough.
I'll go back to sleep now.
Posted: Sat Apr 18, 2009 11:16 pm
by MGFmad
Sleep tight!
Posted: Sun Apr 19, 2009 7:52 pm
by Alec
Hello all,
"but again it's not too important that it be 'exactly' fully open - visual check will be fine !"
up to a point, but try and be as accurate as possible as cams have a 'quietening ramp' and although the valve is closed for some time the gap will be diminishing as it comes close to the opening part of the flank. In practice it is quite easy to judge when a valve is fully open and then to adjust the relevant valve.
As a Triumph 2000 owner also, they seem to have a rather unusual valve setting procedure as two valves are adjusted simultaneously, e.g 1 and 3 fully open, adjust 10 and 12. It follows the rule of 13 (for a six cylinder), but twice as fast as conventional sixes?
Alec
Posted: Sun Apr 19, 2009 10:27 pm
by bmcecosse
Same for the A series - you can adjust two valves at the same time - just note which two are more or less open. and adjust the two opposites! The valves really are closed for a very long period of the cam - the ramps are well away from the base circle (closed) section.