Off idle hesitation - solved
Conventional wisdom (and the FSM) says that the screws should be set at the same number of turns.
Conventional Wisdom? Is that like asking Joe down the street and Bob at the bar?
Lets think about this. There are a number of reasons the other guys already laid out for having individual idle mixture valves (aka screws). At least for me, the technical rationale outweighs the popular thoughts on any technical matter.
Now as far as the FSM, you've got my attention. I too would like to know where you saw this. Seriously. I'm betting what you saw was a starting point after an overhaul. Take another look and let us know.
This engine is built recently. Cam, head shaved, block shaved, etc.
Well, well, well.
This would have been helpful to know before I started digging in the FSM.
Once the compression and cam has been changed the factory settings no longer apply. Depending on how the changes effect the compression and valve overlap the factory specs might be a clue as to a new baseline to tune from.
What I'm saying is that tuning a hot rod is really that. It's a process.
Links if you are interested in learning more
Basic Concepts:
Timing is related to engine speed and fuel mixture.
Fuel to Air needs are mostly related to load.
Changes to manifold vacuum will impact the low speed fuel circuit, espcially at idle. Illustration
here. So factory settings may have to be altered.
Increased overlap will allow more exhaust to stay or even get pushed back into the combustion chamber at idle. This calls for more lead time between the spark and and when the piston is going down.
Increased compression will created higher fuel density in the chamber and also more heat. Therefore will require less spark lead time.
Practical Performance Tuning:
Tune for Best Performance
