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  #1  
Old 10-10-2015, 02:10 AM
Sylvainsting's Avatar
Sylvainsting Sylvainsting is offline
 
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Default St James cowl recommandations

Hello,

I plan to begin my James cowl installation. I read a lot of post about but I am still a bit confused to how proceed.
Do you have some recommendations for me, what to do and what not to do ?
Or if you have to re-do it what do you change or add to have the best fit/result ?

In advance thank you for your help
Sylvain
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  #2  
Old 10-10-2015, 06:03 AM
BillL BillL is online now
 
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Quote:
Originally Posted by Sylvainsting View Post
Hello,

I plan to begin my James cowl installation. I read a lot of post about but I am still a bit confused to how proceed.
Do you have some recommendations for me, what to do and what not to do ?
Or if you have to re-do it what do you change or add to have the best fit/result ?

In advance thank you for your help
Sylvain
The James cowl fitting is not much different than others. Here are DanH's instructions on the beginning. For SJ - I made a 2 discs from cardboard with a marked center the size of the OD of the inlet ring, also make a disc, like Dans picture, I made a wooden one with a center hole that tightly fits the prop extension guide for the prop. This centers it on the crankshaft. Also drilled/clecoed the disc to the upper and lower cowl for easy removal trimming and prefect repositioning for further checking. I did not worry about the droop that might happen to the engine with time. If that happens, then I will just shim the mounts to compensate. Only deal with the issue if it appears. While you are marking the circles on the wood disc, make a circle for the prop bolts, you might need them to space out the disc.

If you have the Hartzell composite prop, you will need to address the full pitch blade clearance. An entirely different decision to me made.

After fitting the front, the disc will keep the halves aligned until you glass the tabs between the air inlets and prop. This will come later after all the sides and back have been fitted.

Remember - you are fitting to what you have, not to some "design" dimensions. The cowl split is not horizontal, i.e. parallel to the fuse rail. I have some other posts for how I installed the inlets.

The SJ cowl has the plane of the prop flange, and the inlets in the same plane. Vans does not. Vans inlets are shifted to the rear. Just a design difference.

With the information above, you should be well on your way for fitting.

Question - do you have the short or long cowl, and what engine?
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RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”

Last edited by BillL : 10-10-2015 at 08:03 AM. Reason: added question.
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  #3  
Old 10-10-2015, 07:38 AM
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N941WR N941WR is offline
 
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When you get to the cooling plenum, there are two things you want to consider:

1. The front of the cooling plenum will not fit your engine. You can solve this with either of two ways; option one is to cut the front of the plenum off and use the aluminum baffles across the front and cut the plenum to match, adding a vertical lip, as needed. Option two is the trim the front of the plenum, put mold release on the front of the engine, and lay new fiberglass right on the engine and plenum, making a custom fit. (I did option two and it has worked very well.)

2. Put the plenum up as high as possible. This will give the air space to slow down and will help with cooling.

The third piece of advice I would add is to make the air dams that go in front of the front cylinders removable so you can trim them to balance your cooling needs.

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RV-9 (Yes, it's a dragon tail)
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  #4  
Old 11-13-2015, 11:17 PM
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Hello,

Thank you for your replies.
Bill, do you have some pics which help me ?

In advance thank you
Sylvain
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  #5  
Old 11-14-2015, 04:02 PM
Rupester Rupester is offline
 
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As others said, the process is generally the same as fitting a Vans cowl. My James cowl and plenum came with instructions that outlined the basic steps and order.
My "speaking from experience" advice is to make sure you have the spinner aft bulkhead and prop extension before you fit the cowl .... Certainly at least before you permanently establish the firewall to spinner dimension. I tried otherwise and ended up requiring a custom prop extension, since I didn't know about the aftward flange on the backplate for the Vans spinner, and had to account for it AFTER having finalized the cowl trimming. Certainly not ideal.
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  #6  
Old 11-14-2015, 05:07 PM
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N941WR N941WR is offline
 
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Here are some pictures that may help.

One other suggestion, mark the top cowl where you want to cut the oil door, cover the cowl with stretch wrap, and lay multiple layers of fiberglass over it. When the fiberglass hardens cut out your oil door. Then lay that door on your cowl and trace it. Once you cut the hole in the top cowl, you should have a good fit.
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RV-9 (Yes, it's a dragon tail)
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www.repucci.com/bill/baf.html

Last edited by N941WR : 11-15-2015 at 05:50 AM.
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  #7  
Old 11-15-2015, 01:21 AM
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Sylvainsting Sylvainsting is offline
 
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Hello bill,

Thank you for the link but it don't work..
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  #8  
Old 11-15-2015, 03:18 AM
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Sylvainsting Sylvainsting is offline
 
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Hi Terry,

Thank you for your advises. In my case there is no problem because my 200RV WW propeller came with its own spinner. I with install them on Monday to fit better my plenum.
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  #9  
Old 11-15-2015, 03:31 AM
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Sylvainsting Sylvainsting is offline
 
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Default Plenum issue

HI,

But there is some issues to fix. The plenum don't fit very well at the front and I don't know if it is better to cut the fiberglass and redo it or to fill the holes with RTV.

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Flying...
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  #10  
Old 11-15-2015, 05:56 AM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by Sylvainsting View Post
Hello bill,

Thank you for the link but it don't work..
Sorry about that, it is fixed now.

As for the plenum not fitting, I had the same issue.

I cut the front lip off, attached the plenum to the aluminum baffles so it wouldn't move, covered the front of the engine with mold release (I used Vaseline), and then laid additional layers of fiberglass right on to the engine. That gave me a perfect fit.
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RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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