[AX-O]

Starting to look at the cowel/intake/plenum/baffles installation. The Vans instructions say to fit the upper cowel first. The Sam James instructions say to fit the lower cowel first. I am confused on what should be my starting point. Do I fit the baffles, intake, the lower cowel, upper cowel and the plenum? Can you give me the plus and minuses for starting one way versus another? To me it makes more sense to fit the baffles, lower cowel, the plenum, the upper cowel and the intake last.

BTW, I have an RV-4/O-320/Sam James Cowel/Sam James plenum/fixed 3-bladed Catto prop.

 

[Norman CYYJ]

I find it easier to mount the top cowl first. It then gives you a good reference point to work from. I make a plywood disk the size of the spinner back plate mount that on the flywheel the same distance that the finished position of the spinner backing plate will be when mounted. I then can drill into it and then drill into the cowling to hold it in place. If you mount the cowling a bit proud of the disk it will allow for future engine sag. Hope this helps you.

 

[AX-O]

I make a plywood disk the size of the spinner back plate mount that on the flywheel the same distance that the finished position of the spinner backing plate will be when mounted. I then can drill into it and then drill into the cowling to hold it in place.

Do yo have a picture? I have a 4-inch extension on my flywheel.

 

[pierre smith]

Hi Axel...

...We mounted the extension and the spinner backplate to the engine...both on my -6 and my buddy's -4. Mount the top cowl and align it with the spinner backplate. You can cleco short 3/4" angle pieces to the top cowl that lie on the backplate to hold the cowl correctly while you mark and cut the sides and top to proper dimensions. We also duct taped the cowl to the upper skin to hold it securely.

Then fit the lower cowl and align it to the top.

Now make and fit the baffles....you'll put the top cowl on and off a bunch in order to trim the baffles to the required height.

Regards,

 

[Norman CYYJ]

Sorry, no pictures. I used plastic PVC 1/2 pipe for spacers on the prop bolts. If you go this route make sure you make an allowance for the thickness of the spinner backing plate. The plywood disk was the same diameter as the spinner plate.