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Following an odd fault in my 3A which I thought was caused by a valve problem I have just overhauled the cylinder head. The initial fault was a severe spitting back through the front carburettor. Unfortunately, whilst reduced, I still have the fault! When setting the tappers I noticed that a couple of the rockers, including No1 exhaust did not depress as much as the other valves. I am now leaning towards a worn camshaft. Anyone have any comments? Could this have caused the initial problem. ie exhaust valve not opening fully. Having just put it all back together I’m not too buoyant right now.

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Check the rockershaft for wear or picking up.

Mick Richards

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In case anyone is interested the fault on my 3A causing blowback through the front carb was due to a worn cam lobe. Cylinder 1 exhaust was worn quite badly but cylinder 2 exhaust was almost round! The photos show a nice lobe and a very not nice lobe! Prior to discovering this, blaming poor valves, I had refurbished the cylinder head and only noticed the poor valve opening when adjusting the tappet clearances when my head was at eye level with the rockers. My other hand was up inside the wheel arch turning the engine over using my precision made one man crank turning device. (I have no crank handle hole in my radiator now opting for improved cooling over this function). 

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