I am working on a car I have decided to use a pair of truck cast iron exhaust manifolds. Mostly because these happen to fit where every header I had laying around wouldn't. My question is pertaining to the spring controlled heat riser thats only on one of the manifolds. It does move free and doesn't have a loose pivot bore that I am worried about leaking . Should I cut it out or leave it alone. My guess is it is there to push heat up into the intake manifold. My intake has heat block off plates since it is the early 60s longram tubes. Will this weighted butterfly just make noise or is it benifical in some way I am not seeing? I'm thinking of cutting it out and installing pipe plugs in the pivot pin bores to seal it up.