When setting up an 8 stack mechanical injection it is important to arrange the return springs in a specific manner.
You should NEVER pull closed front simply the front or the rear – rather, you have to pull from both.
If you ever expect a good idle, you must arrange for two medium weight springs pulling from the front and rear at the same time.
Reason: The linkage on 8 stacks is by nature, a bit sloppy. This means that if you notice, when you pull from one corner and then follow the linkage from the left or right front to the left or right rear you may find that there can often be as much as .001” to .005” in linkage wear and /or flex.
Since the butterflies adjust to:
It becomes pretty clear that by leaving the front corner or rear corner with no return spring, that you can be rich in the front and lean in the rear or vise versa.
Do NOT use super strong springs – a good choice for a return spring attachment is :
After you accomplish this, then you can expect full closure each time you open and close the throttle.