I have a new engine on which it has a return spring on the Walbro throttle arm.

Should I leave it on, or take it off ? ? ?

Ed

I unhook mine as to take any pressure off the carb servo, but I don't think it really matters. Don't take it off, just unhook the little bent tab on the end of the spring. Brian

DA says to unhook the throttle return spring but do not remove it.

I just asked the same questions and received the exact same answers , so I think we are good to go

I read about this a little while ago too.

The spring has to be left in if you cut the spring end off to keep the throttle butterfly centred in the carb apparently.

Only other reason I can see to keep it is as a safeguard if the throttle linkage comes off. If you have a remote ignition setup tho it's a bit redundant.

Standard servos will turn the arm with the spring attached, and it makes a nice safety mechanism should a servo fail, it will at least naturally 'try' to return to idle or off. If you remove the spring completely, you are taking that side pressure off the throttle plate shaft, and thus, with vibration the plate could then rattle in the bore, and eventually open it to a point where it no longer fully closes....etc. If you feel you must disconnect the spring from the arm, do leave it in place.