[crabandy]

The RobbinsWings Carb Heat Muff comes in 4 or 6 inch versions, which one do I want for my RV7 O-360 crossover exhaust? Is the 4 inch for the O-320?

 

[flyboy1963]

how much heat do you need?

I put the 6" on my 0-320 with typical crossover. I can't imagine why you'd bother with a 4", more heat is always better, right? The 6 is just adequate in my opinion. I'd recommends wrapping the pipe with some kind of heat transfer material; spring coils, stainless steel wool, etc.
call Robbins, they probably have more feedback for you.

 

[crabandy]

Probably don't need as much heat as you do, but winters usually hit single digits. No luck calling yet, I thought I might get an easy answer here. On RobbinsWings website they list 4 or 6 in on the carb heat muff, they don't list an 8. The cabin heat muff they do list a 7, 8, 9 inch for the cabin heat muff though.
Thanks,
Andy