Phenolic spacers are made of insulating material which supposedly keep the air to the plenum cooler than an aluminum (good conductor of heat) would. I was going to buy an aluminum intake but then I heard about these "phenolic" ones. Anybody have any imput or experience with these?

 

Well I've used these for under a carb on my 73. It keeps the carb cool so the fuel doesn't heat up in the bowls, and also keeps mixture a little more true. On the 4.6 I can't see where the air could be heated that much in the plenum for it to do anything. Then again it cant hurt [8D]