Engine Tuning 2

I don't have any "set" way to tune, the engines tell me what they want. When it comes to fine tuning, I usually tune in the LSN first, but only after running the car and leaning the HSN til it sings up good.

Once you know the motor sings up you know the HSN is in the ballpark, then I'll set my LSN by observing the idle. There's a pretty big window where the car will run OK, but still be off in tune. The "let it sit and pin it" test works OK IF the idle is set correctly.

I'll run my car to temp, bring it in, clear it out. If the idle hovers high for a long while and eventually drops, I'm too rich on the LSN. This is because the idle needed to be set high, cleared out the mixture is good, the motor will rev. If really rich this will cause revving in the air for sure. As I lean the LSN I also drop the idle, otherwise it will stay high. There's a point where the engine's idle either drops IMMEDIATELY to idle, and or the idle goes up and down, this is the point of being too lean. I'll back up 1/4 or 1/2 turn from there.

I set my LSN so when cleared out the idle hovers high for a second or three, and then drops to a nice tick, and then if left to idle it eventually loads up and dies. As long as the LSN is perfect to slightly rich you'll get the puff of smoke when you let it sit and pin it.

The LSN is much more important than the HSN. It determines what kind of economy you'll get, and it controls how quickly the engines gets up to song. There's running hot due to a bad tune, and there's running hot with a good tune. If the LSN is set correctly, the engine will run good and consistant, and the HSN will adjust top end power and temp, but the ngine will run great regardless of temp. Once you know what to recognize setting the LSN and which way to go with it becomes pretty easy.

Another thing to watch is consistancy. If the tune changes during the race it's usually due to a needle being lean. If it remains consistant but runs like crap it's usually a needle being too rich.