Mailing List flyrotary@lancaironline.net Message #67591
From: Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Milling exhaust manifold flat?
Date: Sat, 27 Jan 2024 19:36:08 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Want to add a second O2 sensor to my exhaust pipe, so I started to read up on best location. Came across a Holley youtube video where he mentions that even a pinhole could give a false reading. I did a smoke test on the exhaust manifold (soldering iron in jar with baby oil, hoses to/from in lid) and found that I have two tiny pin holes in my weld. Wonder if that really would make any difference, but a 0.040 crack between engine block and flange (even with the SS gasket) might lead to a lean reading. There are signs of slight blow-by there. So I think I'll go through the trouble to mill all flanges flat.


Finn

On 1/26/2024 3:08 PM, Finn Lassen finn.lassen@verizon.net wrote:
When I welded on my stock Renesis exhaust manifold the end I welded the 270 deg bend on got warped.

It's about 0.04" bent away from completely flat at the top flange at flywheel  end.

Doesn't seem to have been an issue during the 100+ hours the engine has run.

But for peace of mind I'm wondering if I should mill the three flanges flat.

Is it true that I'll need a carbide end mill to do this? Even a 1/2" carbide end mill is close to $30.

Finn


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