5.0 surge

[keithm]

84 model motor, 289. Edelbrock intake , 625 carter afb, aod trans.

This may be more of a question for the mustang group. After a routine carb clean and tune up, I now have an off idle surge, it seemed to start at a gentle steady cruise around 1500 rpms. And was gone by 1800. My thought were the metering springs were to light and caused the vacuum to hold the pistons down leaning the mixture. I did a once over and noticed the metering springs were different lengths, so I installed the base setup orange springs started it up and went for a ride, once it was at temp. I noticed the same issue. I'm thinking of trying an even stiffer spring.

Anybody run into that before?

 

[RonD]

Regular vacuum(below throttle plate) decreases as RPMs go up
Ported vacuum(above throttle plate) increases as RPMs go up

Could the throttle plate itself have a leak around it's shaft, so at a certain point it leaks then doesn't.

What is running off the Ported Vacuum?
Distributor?
EGR?
Are the Ported vacuum ports capped well if not being used?

PCV valve should be on a regular vacuum.


What distributor are you using, and what type of advance system, maybe when advancing it has something loose.