Phenolic spacers

Has anyone used used phenolic spacers between the head and intake manifold. Im using a billet/sheet metal manifold and it gets dam hot. Trying to look at ways to reduce temp.

Have added extra bonnet vents which has helped.

Seems like a great idea. If you can't find something for your application, here are some clues to using PTFE (Teflon) sheets:

https://tech.mirage-performance.com/teflon-insulating-gasket.html

links are bad, but here is another source to give you an idea of prices for PTFE that could be cut / machined:

https://www.mcmaster.com/sheets/chemical-resistant-slippery-ptfe/chemical-resistant-slippery-sheets-and-bars-made-from-teflon-ptfe/

Sourcing the materials is easy its just if the cost is worth the result.

There will be a benefit, but how much is impossible to say as there are many factors involved, with only one being the heat from the cylinder head - heck, if it's bad enough, the head may even be drawing heat from the manifold.

There are three ways heat is transferred - direct physical contact, radiation or convection

There are other things that may also help - using thermal paint on the manifold assembly, some have reported good results with chroming but that may be expensive, perhaps some form of heat shields can be formed with, maybe, a forced air flow arranged through it?

I went from a cant touch from heat intake manifold to a cool manifold, then after adding a small wmi nozzle post intercooler to a manifold that sweats in the texas heat even after a 9000rpm 30+psi blast around COTA. I have a 15mm thick spacer between manifold and cylinder head. Worth the $75 bucks to me.