What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

St James cowl recommandations

Sylvainsting

Sylvainsting

Active Member
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
 
Sylvainsting said:
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
Click to expand...

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?
 
Last edited:
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.

2012-07-04_15-38-52_41.jpg
 
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.
 
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.
 
Last edited:
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.
 
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.

 
Sylvainsting said:
Hello bill,

Thank you for the link but it don't work..
Click to expand...

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.
 
I had the same plenum issue - I found the easiest way (for me) to solve it was to cut the plenum back a considerable amount, and I fabricated an aluminum sheet of .040 material that I custom-fit to the engine block profile, and then bonded that to the plenum.

As an alternative you could wax the engine block with mold release and do a fiberglass layup directly onto the block, but you'll have a good cleanup job afterward.
 
Sylvain,

I had to do some maintenance today, so after pulling the cowl, I took this picture and put in the Picasaweb album with the others. I also added fiberglass where the cooling plenum meets the aluminum ramps.

All that said, Dan is a master craftsman, and he made a good suggestion. However, since you already have the plenum, modifying it isn't a big deal.
 
You must log in or register to reply here.
Back
Top