Enough heat coming through the screws to vapor lock your engine is quite interesting. I took a peak at my Baja last night and, indeed, the bolts go through the spacer to the motor. I don't believe there is any other option for mounting with them. The stock carb spacer is some sort of plastic; it reminds me of bakelite. Maybe these gaskets may help you with your troubles http://www.davesmotors.com/s.nl/it.A/id.871/.f http://www.davesmotors.com/s.nl/it.A/id.872/.f An interesting property of aluminum is its ability to conduct heat, which it does about as well as it conducts electricity. I haven't been following hpibajaforum.com in some time now, but when I was, I never heard of anyone complaining of a vapor locked carburetor. It could be something unique to rear-carbureted engines.