I would like to run one of these spacers. Does anyone know why the composite spacer is for "race only"? I was hoping to get some carb heat insulation with the spacer. How well does the aluminum spacer insulate the carb from heat? Thanks for your time

Aluminum does not insulate worth a darn. If heat transfer is a concern, get a spacer made of phenolic resin.

- John

Composit spacer is plastic and they don't want it to warp from the heat and cause you a vacuum leak.

I've never had a plastic spacer do that,and I've ran them on daily drivers.
I've never owned one of those HVH Spacers though maybe they can't take it,dunno.

You can try the laminated wood ones also. I have the 1/2" devided wood one from Edelbrock to match my Performer RPM.