TKOPerformance wrote:

Phenolic is a better insulator.  Will it make any real difference in how the engine runs?  Probably not.  If you don't have issues now I'd be inclined to leave well enough alone.  If you had a heat soak issue causing vapor lock I'd say try it, but for any kind of a performance gain I don't see it. 

X2 on the comment for a phenolic spacer. Hard plastic is an option as well but I will stick with a phenolic.  


Out of curiosity, does the existing spacer route water from the cooling system through it? some did for other motors in the past. 
 

TKOPerformance wrote:

Phenolic is a better insulator.  Will it make any real difference in how the engine runs?  Probably not.  If you don't have issues now I'd be inclined to leave well enough alone.  If you had a heat soak issue causing vapor lock I'd say try it, but for any kind of a performance gain I don't see it. 

Ha, ha... I am not expecting performance upgrades from this. I have just seen a lot of people talk about using a phenolic type spacer. I haven't had the carb boiling the fuel or anything, so maybe I am ok with the original aluminum spacer?
 

Phenolic is a composite made from a phenolic resin (heat and pressure activated with a formaldahyde base) and some form of reinforcing (paper, fabric, fiberglass, etc.).  It was very popular before plastic was widely used.  Its still used a lot for electrical insulators and for heat isolation.  Its also light compared to a lot of other materials.  There's a local company we do some work for from time to time that manufactures parts from it.  Its really neat stuff.  They've got it in all different colors, compositions, etc.  Looking at it though you can always tell is composed of more than one thing due to color variations.  The plastic spacers are always a solid color, and thus, I believe are made from some form of plastic. 

If I had to buy a new carb spacer I'd get a phenolic one without hesitation.  I wouldn't change to a spacer of the same configuration though unless there was an issue.