Thermoquad questions

I had to install a heavier spring on the air door of mine on a 340 with .528 solid cam to prevent bogging with a 4 speed. I kept tightening the original until I almost had the bog out and the original spring broke. I got the heavier spring out of one of those assorted spring blister packs at the parts store. I was using a Thermoquad from a 440 if that matters. It ran great after that little modification.