lml@lancaironline.net Mailing List Archive

Here is a thought that I have never heard anyone mention. If you look at most exhaust installations, in many cases the exhaust wraps around under all of the cylinders at 1500 or so degrees...Ok, see where I am going here, I double wrapped (triple in some areas) all of my exhaust system with that hotrod manifold wrap. Keeps the hot stuff in the pipes where it belongs. It may also be contributing to hotter cylinder and oil temps. I would also make sure your exit gaps on the bottom baffeling are not too tight. I opened mine up a little and also rounded the bends where the hot air exits under the cylinder near where the safety wire goes instead of 90 % corners. It helped some. I run around 350 F and 395 max on hot days in a long climb...
I like Lorn's idea on timing as well..

Hope some of that helps..
Randy Snarr
N694RS
235/320

--- On Sun, 7/18/10, Lorn H Olsen <lorn@dynacomm.us> wrote:

From: Lorn H Olsen <lorn@dynacomm.us>
Subject: [LML] Re: My airplane is running HOT
To: lml@lancaironline.net
Date: Sunday, July 18, 2010, 11:47 AM

Bryan,

The vernatherm is a distinct possibility. If it is a vernatherm problem, it may just be that the vernatherm is not seating correctly. Lycoming has a tool that you could obtain and use to smooth the vernatherm seat.

When I started flying my plane after the last engine teardown, the CHTs went up to 480 in the climb and the EGTs would not go over 1,300. Normally in the climb my CHTs go up to 440 and the EGTs are up to 1,500. After all of the other checks, I had the timing looked at. The left mag was set at 50° BTDC instead of 25° BTDC. Correction of the left mag timing fixed the problem.

Now I know that high CHTs and low EGTs can mean advanced timing. Visa versa, low CHTs and high EGTs can mean retarded timing.

Lorn

> Date: July 16, 2010 11:21:15 PM EDT
> Posted for Bryan Wullner <vonjet@gmail.com>:
>
> Anybody have any ideas or advice for the following situation:
>
> Lancair 360 with carbed 360 (180hp) engine. 475 hours on it about. Chrome
> Cylinders. I have a Plenum cooling system and larger cowling inlets.
> (Zavatson's cowling and plenum system)
> Oil cooler is mounted at the front inlet.
> Oil wont cool in climb and will go up to 230 and probably higher if not
> stabilized. CHT's are all hot in climbs and will go to 440 no problem. Cant
> figure it out.
> Motor runs great, compression good, boroscoped fine, mag timing good. All
> leaks in plenum or baffling are sealed.
> Probes were checked out ok.
>
> Only thing I haven't checked is the vernotherm.
>
> Thanks for any advice.
> Bryan
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,700 hrs, N31161, Y47, SE Michigan

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