I am working on 3 Poulan saws and I notice all 3 have a "heat shield" insert in the cylinder head out to the muffler. Just a stupid question plus I am learning and I couldn't find the answer with a google search or here. I am sure its been answered before and I am over looking it. Are these needed? Do they help or do they restrict the exhaust? I posted a picture below of what I an taking about.
https://imgur.com/a/PuOoIAQ
https://imgur.com/a/PuOoIAQ
