supermalc
Well-Known Member
The 9 rule will only work with a 4 cylinder engine, with a firing order of 1243 or 1342, and a valve configuration of exhaust inlet, enlet exhaust, exhaust inlet, inlet exhaust.
The find tdc compression stroke with valves rocking on 4 to adjust 1 etc. will also only work with these firing orders on a 4 cylinder engine.
To fail to adjust the valve clearance properly can be catastrophic. In the late 80s I bought a 1600cc Renault diesel engine with a broken camshaft for spares. Pushrod engines have several mechanical parts which wear. Camshaft to cam follower; cam follower to pushrod; pushrod to rocker arm; rocker arm to valve. Also the long thin pushrod tends to get compressed slightly. So the valve clearance usually become greater.
The valve clearance on overhead cam engines tend to close, as the valve sinks into the seat more than the wear of the mechanical parts. This stops the valve closing properly when the engine is cold, and the metal has not expanded. The resultant poor starting on this engine was overcome by the dreaded Easy Start (see my post on Cold weather engine starting problems). I suspect this worked for a while, until the resultant starting explosion caused the valve to press onto the camshaft so hard it broke, also breaking the cam bearing housing in the head. The cost of repair far outweighed the value of the engine.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://www.angelfire.com/rnb/malcsworld/>http://www.angelfire.com/rnb/malcsworld/</A>
Take a look at my boating pages.
The find tdc compression stroke with valves rocking on 4 to adjust 1 etc. will also only work with these firing orders on a 4 cylinder engine.
To fail to adjust the valve clearance properly can be catastrophic. In the late 80s I bought a 1600cc Renault diesel engine with a broken camshaft for spares. Pushrod engines have several mechanical parts which wear. Camshaft to cam follower; cam follower to pushrod; pushrod to rocker arm; rocker arm to valve. Also the long thin pushrod tends to get compressed slightly. So the valve clearance usually become greater.
The valve clearance on overhead cam engines tend to close, as the valve sinks into the seat more than the wear of the mechanical parts. This stops the valve closing properly when the engine is cold, and the metal has not expanded. The resultant poor starting on this engine was overcome by the dreaded Easy Start (see my post on Cold weather engine starting problems). I suspect this worked for a while, until the resultant starting explosion caused the valve to press onto the camshaft so hard it broke, also breaking the cam bearing housing in the head. The cost of repair far outweighed the value of the engine.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://www.angelfire.com/rnb/malcsworld/>http://www.angelfire.com/rnb/malcsworld/</A>
Take a look at my boating pages.