This is a minor detail that I would like to know about before I even take this one apart. I am preparing to tear into a 1981 5 horse flathead. Minor performance mods for a homemade yard kart project with my 9 year old son. We plan to keep it as stock looking as possible. Pulsa jet carb, 3 qt tank.
I have been doing some reading and I have a 4 horse that we are taking apart and he is learning what all the parts do. We are planning to shave the eyebrows, clean up the ports a little bit, do a 3 angle valve job and a thinner head gasket.
The 4 horse engine holds the intake valve open a few thousandths of an inch for about half of the compression stroke. I assume this is a compression release for easier starting. I also assume it stays that way after the engine is running. I suspect that might not be good for performance.
My question is this: If we decide to defeat this function, would we be better to grind the end of the valve stem to increase lash and close the valve, or gently grind the cam down to close the valve on compression stroke?
It seems to me that grinding the valve stem would reduce valve lift on intake stroke and decrease flow.
Please someone, tell me not to worry about it, or tell me what you folks have done to get around this. Thanks in advance.
Dave
I have been doing some reading and I have a 4 horse that we are taking apart and he is learning what all the parts do. We are planning to shave the eyebrows, clean up the ports a little bit, do a 3 angle valve job and a thinner head gasket.
The 4 horse engine holds the intake valve open a few thousandths of an inch for about half of the compression stroke. I assume this is a compression release for easier starting. I also assume it stays that way after the engine is running. I suspect that might not be good for performance.
My question is this: If we decide to defeat this function, would we be better to grind the end of the valve stem to increase lash and close the valve, or gently grind the cam down to close the valve on compression stroke?
It seems to me that grinding the valve stem would reduce valve lift on intake stroke and decrease flow.
Please someone, tell me not to worry about it, or tell me what you folks have done to get around this. Thanks in advance.
Dave