James plenum question

[Charles in SC]

I am installing mine now. My question is does the plenum need to be secured to the engine case in the front center and rear? The plans do not show it being done. In flight if pressure balloons the plenum up, does it go up enough to matter?
Thanks in advance!

[rockwoodrv9]

If I understand your question, no it does not. The only place anything secures the cowling is the firewall. You will be surprised how solid it feels once all fastened.

Sorry - I was reading plenum and thinking cowl. My plenum is only fastened to the baffling. I have some pictures. If you want, send me an email and I can send them. Have fun.

Here is one of my plenum as it gets ready for paint

[sjhurlbut]

No plenum is only fastened to baffling on 3 sides. Mine has front aluminum rings that provide some support against cowling but screws around circumference is what holds it

[N941WR]

Set the plenum up as high as you can. That will allow the air to slow down before going out through the cooling fins.

The front doesn't fit well, so I cut it off, lathered up the nose with Vaseline and laid new fiberglass right on the engine and glassed the plenum to the nose. I then cleaned up the fiberglass.

This is much better than using half a tube of RTV to seal the nose of it.

[Charles in SC]

Thanks, it seemed to be pretty strong and I did not think it was needed but when you do a search and read some of the archives some posters seemed to be convinced that it would lift enough to leak to much air.

[sbalmos]

Lurking in the background here also, about to start fitting my plenum next weekend or so. I know I've read the plenum can be a hack-job. But glad to hear it's usually in the front. I was starting to wonder how many had to seriously carve out the "front nose bridge" between the two air inlets. Mine, at just laying it on top of the engine, seemed like I'd have to carve it out quite a bit to get past a case bolt in front of #1, and past the prop governor oil outlet plug in front of #2.

Just curious, for baffle trimming and initial fit purposes, how high up off the engine do you all have your plenums?

[rockwoodrv9]

Scott, I put mine in about as high as I could. I had to cut and re-shape a bit to get it low enough to clear the cowl in front right above the cylinder. Right now I have about 3/4" from the cowl at the front two corners.

[Rupester]

Originally Posted by N941WR

This is much better than using half a tube of RTV to seal the nose of it.

The SJ plenum fit to my IO-320 was pretty good ... much better than what I see for the guys with O-360s. I sealed the front center to the engine case with some higher-temp red weatherstripping (silicone) from McMaster-Carr. Worked very well and still seals tight after 4 yrs.

[airguy]

I love having the plenum versus the baffles on my plane - but if I ever build again I'll just do the plenum from scratch. I had to do so much cut/reglass work on the James plenum that it was not the effort in my case. My experience may be atypical, but I had to hack both rear corners and the entire front. The only part that was unmolested was the top and most of the sides. As Terry says above, the 320 seems to work better than the 360, I have the 360.

[rockwoodrv9]

Here is a picture of the plenum in place. I need to add nut plates, prime, and paint - then it is DONE! Finally!!

[IMG][/IMG]