[Bob Hoffman]

I am rebuilding a 6A, I had purchased a complete cowling/snorkel to replace the dammaged old one.
The engine/prop has a 4" spacer so I had to add 2" to the rear of the cowling -- no problem -- everything seems to be fitting fine.
THE PROBLEM IS I FORGOT TO EXTEND THE SNORKEL 2" also which makes the snorkel 2" shorter than the rear of the cowl.

My question is would this be a problem if left as is ?Ascetically it looks fine
but I'm concerned about the air flow around the exhaust and the cooling air exiting the bottom --- Any thoughts ???
Thanks
Bob

 

[Mike S]

Got any photos???

 

[Bob Hoffman]

Ya Know, I knew that sooner or later I'd have to figure how to post pictures here, I'm surprised I got away with it so long.I'll see what I can do,but in case I'm not successful I'll try and explain what I'm talking about.
If you take the lower half of the cowling and stand it up on the firewall edge and then take the carburetor air scoop (scoop and cowling are two seperate pieces) and place the scoop where it needs to be for the carburetor needs it to be, the trailing edge (cooling air exit/exhaust pipes exit) is 2" short of the cowling firewall edge. Fitting it that way is not a problem, but is it a problem with the cooling air exit airflow ?? Does it create a pressure problem where the air wants to go into the opening instead of letting the air out? Or it won't make any difference?
Your help is greatly appreciated.
Bob

 

[CNEJR]

I actually..........

ended up trimming the back edge of the scoop where you are speaking of to help cooling. It worked well and did help the temperatures. I also cut my exhaust pipes just about flush with the scoop at about 35 degrees, no drumming or anything. All worked well, give it a try.

 

[Sam Buchanan]

Ya Know, I knew that sooner or later I'd have to figure how to post pictures here, I'm surprised I got away with it so long.I'll see what I can do,but in case I'm not successful I'll try and explain what I'm talking about.
If you take the lower half of the cowling and stand it up on the firewall edge and then take the carburetor air scoop (scoop and cowling are two seperate pieces) and place the scoop where it needs to be for the carburetor needs it to be, the trailing edge (cooling air exit/exhaust pipes exit) is 2" short of the cowling firewall edge. Fitting it that way is not a problem, but is it a problem with the cooling air exit airflow ?? Does it create a pressure problem where the air wants to go into the opening instead of letting the air out? Or it won't make any difference?
Your help is greatly appreciated.
Bob

It is likely the increased exit area will enhance cooling, opening up the exit area is a common remedy for high CHT's. The downside is potentially increasing cooling drag since more air will be trying to flow through the engine compartment.

In the real world, it probably won't make much difference. Get your plane flying, you can tighten up the opening later if you wish.