I created a recent thread where I was trying to sort out my lack of idle, and resolved it through correct slow speed needle adjustment. It's a 1968 Johnson 6hp.
HOWEVER, although it idles fine when cold after starting, it has real problems idling when hot after a run. The engine has a nice even running sound when cold, but when hot it develops more of a 'chugging' type of sound at idle, and stalls after about 30 seconds.
The sound is not dissimilar to the sound it made when I was testing crankcase pressure. I used a gravity fuel feed, removed the fuel pump and plugged the pulse hole. When the pulse hole was partially unplugged, the engine made a similar sort of sound, and died fairly quickly.
So I'm wondering if I'm losing crankcase pressure when the engine is hot? Is this possible? Could there be any other causes of a poor idle when hot?
The engine has had a complete set of new ignition parts, a fully overhauled carburettor and new head gasket.
HOWEVER, although it idles fine when cold after starting, it has real problems idling when hot after a run. The engine has a nice even running sound when cold, but when hot it develops more of a 'chugging' type of sound at idle, and stalls after about 30 seconds.
The sound is not dissimilar to the sound it made when I was testing crankcase pressure. I used a gravity fuel feed, removed the fuel pump and plugged the pulse hole. When the pulse hole was partially unplugged, the engine made a similar sort of sound, and died fairly quickly.
So I'm wondering if I'm losing crankcase pressure when the engine is hot? Is this possible? Could there be any other causes of a poor idle when hot?
The engine has had a complete set of new ignition parts, a fully overhauled carburettor and new head gasket.
