James cowl heat intake question

I am building a -7 with a long James cowl. My question is where is a good place to take air for the heat muff? The pictures included with it shows the cabin air coming off the rear baffle behind #3 cyl. The picture is of a -4 and does not look like it has any heater. I have an IO-360 with the muff on the #1 exhaust header. Van's shows taking the air from the baffle in front of the #1 cyl. Hope all this makes sense. Thanks in advance!

Charles,

I am taking mine off the rear of the baffles. I have the same set up on my RV-7A project. I am using a Bill Lane plenum, which is a major improvement over the Sam James plenum. It has separate inlet diffusers, which can be easily lined up with the intakes.




Frank Huber
RV-7A project

Mine comes off of the #3 baffle, where it angles towards the cylinder head.


I have the James short cowl and it works fine.

Where to place the heat muff depends a lot on the exhaust style you have. I have the long James cowl and take the air off the back of the #3, then run it forward to the heat muff on the #1 exhaust, only place available with the long James cowl and Vetterman crossover.

So far it's adequate, but not excellent, at outside temps in the positive teens. One or two hours flights are great - but the fourth or fifth hour, especially in the dark, get pretty chilly.

Thanks, I have not tried it yet but it does not look like there is room to run the scat tube forward to the muff.