Originally Posted by
Timox
Just tried it again. Still doesn't want to idle stable. Tried another Nova carb and that didn't change anything either.
I was able to stop the first initial low idle drop off at the end of the straight by leaning the high end a little. But the low end is as lean as it will go and i still have the extremely high idle at first then drops back to a very very low idle. That too me says its still too rich on the bottom but its at the point of lean bogging at the end of the tank now so i cant go any leaner ???????
No air leaks in tank or lines
No leaks in engine
Fresh clutch and clutch bearings
Different carb
?
?
If a engine still has a tight pinch you will never get rid of the multi stage idle down........... Once the pinch relaxes that characteristic will go away
Whats is happening is the friction from the pinch is dragging the idle RPM down...the longer it idles, the cooler it gets and the tighter the pinch becomes.....after a high speed pass the engine has plenty of heat and the pinch relaxes, allowing a high idle...but when you pull in the engine cools and the pinch drags the RPM down...If you tune it to idle good in the pits it will high idle on the track...if you tune it to idle down clean on the track it will idle down and die in the pits....It is not till most of the mechanical pinch is gone that you will be able to get the tune your looking for...... A Plus 4 is a very tight engine and chances are that at 1/2 to 3/4 of a gallon you are still experiencing a fair amount of mechanical pinch...these engines can take 2 gallons to fully break in.......... You should find that the longer you run this engine, the more stable the tune will become...... I notice this multi stage idle with all the Nova's when they are new....But once they loosen up it goes away