air cutoff valve spring

[pastr]

Hello
I have 1986 asp.
I have backfires and hesitation on cold run, after acceleration and warm up it's gone.
I suspect at the air cutoff valve spring, It feel like it's too hard and supposed to be softer.
The spring is part of rebuild I did (randakks kit), I didn't compare it to the previous spring, so I don't know if it's O.k or not.
what is your recommendation?

[virgilmobile]

Going by memory..those springs are very stiff normally.
Is your backfiring in the exhaust or carbs.?

[pastr]

I didn't pay attention but it look like in the carbs.

[virgilmobile]

Ok..pay attention next time.Those cutoff valves are operating only on deceleration.They open with the high vacuum and enrichen the fuel through the hard decell to keep the engine from going lean and prevent exhaust backfire.
Intake backfire could be related if the valves are stuck open or where the plunger is fitted,is binding.Usually tested without the spring first before assembled.