Carb Heat Muff

[jjkrug]

I'm building an RV9A with a carb O-320. The original builder added cabin heat (per OP-29 Cabin Heat) but not carb heat. I want to add carb heat but am having trouble figuring out which heat muff to use on the exhaust cross over.

The OP-54 drawing show a common heat muff for both carb heat and cabin heat. That won't work because I already have the cabin heat muff under #3 cylinder.
I need a single muff that will go on the front crossover and will bring air down from the air intake then to the air box.

Van's has a muff that looks like it would fit but is only for 1 7/8 exhaust. I have a 2" crossover.

Any ideas?

 

[PaulvS]

I'm building an RV9A with a carb O-320. The original builder added cabin heat (per OP-29 Cabin Heat) but not carb heat. I want to add carb heat but am having trouble figuring out which heat muff to use on the exhaust cross over.

The OP-54 drawing show a common heat muff for both carb heat and cabin heat. That won't work because I already have the cabin heat muff under #3 cylinder.
I need a single muff that will go on the front crossover and will bring air down from the air intake then to the air box.

Van's has a muff View attachment 79398 that looks like it would fit but is only for 1 7/8 exhaust. I have a 2" crossover.

Any ideas?

There are a couple of options;

1) Locate a second heat muff for carb heat on the left hand side of the exhaust tailpipe (in mirror position to the heat muff for the cabin heat). Aircraft Spruce has Turbo heat muff available in 2". Van's also has DL05 in 2" that you could use:

2" Exhaust Heat Muff

The 1.75" Exhaust Heat Muff fits on either the left or right side of many exhaust systems with 1 " diameter tailpipes. Later exhausts have 2" tailpipes and require the VENT DL-05 2". 8" Long, 4 1/2" from the center of inlet hole to the cente

store.vansaircraft.com

2) Fabricate your own heat muff to fit over the crossover pipes above the FAB. It doesn't need to be elaborate; several builders in my region have made a wraparound muff from sheet aluminum and a 2" pipe flange and this is exactly what I have done for carb heat. If there is interest I can post a pic.

 

[georgedouglas]

There are a couple of options;

1) Locate a second heat muff for carb heat on the left hand side of the exhaust tailpipe (in mirror position to the heat muff for the cabin heat). Aircraft Spruce has Turbo heat muff available in 2". Van's also has DL05 in 2" that you could use:

2" Exhaust Heat Muff

The 1.75" Exhaust Heat Muff fits on either the left or right side of many exhaust systems with 1 " diameter tailpipes. Later exhausts have 2" tailpipes and require the VENT DL-05 2". 8" Long, 4 1/2" from the center of inlet hole to the cente

store.vansaircraft.com

2) Fabricate your own heat muff to fit over the crossover pipes above the FAB. It doesn't need to be elaborate; several builders in my region have made a wraparound muff from sheet aluminum and a 2" pipe flange and this is exactly what I have done for carb heat. If there is interest I can post a pic.

Please post a picture. I have lost a few muff end pieces on my RV14A and plan to make my own.

 

[AlphaCharlieBravo]

I'm building an RV9A with a carb O-320. The original builder added cabin heat (per OP-29 Cabin Heat) but not carb heat. I want to add carb heat but am having trouble figuring out which heat muff to use on the exhaust cross over.

The OP-54 drawing show a common heat muff for both carb heat and cabin heat. That won't work because I already have the cabin heat muff under #3 cylinder.
I need a single muff that will go on the front crossover and will bring air down from the air intake then to the air box.

Van's has a muff View attachment 79398 that looks like it would fit but is only for 1 7/8 exhaust. I have a 2" crossover.

Any ideas?

Contact Clint at Vetterman Exhaust. He can supply you with the Robbins Air heat muff for the crossover exhaust. Thats what I have on my x over.
I got the 1.5 exhaust for weight savings but he should have them in all diameters.
All the best.
A

 

[PaulvS]

Please post a picture. I have lost a few muff end pieces on my RV14A and plan to make my own.

Here are pics of the DIY carb heat muff shroud over the crossover pipes. The top and bottom half of the "sardine can" clamp to the pipes and air is drawn in through the open ends.