Senior Tech Team
Join Date: Aug 2002
Location: Gold Canyon, AZ
Ed, the primary function of spark plug shields is to reduce the amount of exhaust manifold heat that is absorbed by the ignition wires. Silicon wires and boots were not generally available, or used, thirty years ago. Shields are not necessary with the good quality wires that are available today. Spark plug shields are totally useless and tend to get in the way when headers are installed. Headers tend to be somewhat cooler than stock exhaust manifolds, because the heat is radiated better by the header tubes.
With that said, a restored engine with stock exhaust manifolds looks kind of naked without the heat shields - in my opinion.
64 Chevelle Malibu Sport Coupe (original owner) car now has 427" BB, Jerico 5-spd. trans., Dana 60 rear end.
SAE Member (25+ years)
ASE Master Certified Engine Machinist
AERA Certified Professional Engine Machinist