REFLECTOR: Lycoming IO 360 C1C Valve Problem Question

[Joel Smith]

Well, I agree that it's not likely that the push rod grew. I am thinking 
that an incorrect length was installed. When set up dry (hydraulic 
lifter compressed) the tappet clearance should be .028-.080".  Current 
clearance is 0. If setup properly, something moved .030". That would be 
a lot for a valve to concave. Beside I doubt valves concave a measurable 
amount and maintain structural integrity.

The engine has about 75 hrs. It runs good warm, but now I know that it 
is only because the cylinder's expansion rate at operating temperature 
is higher than the push rod (because it is cooler) and relaxes the 
tappet clearance enough to run properly. There is not enough tolerance 
so I will replace the push rod with a shorter one. In it's current 
state, it could still not be closing well enough to keep from burning a 
valve. I want the proper tolerances so that the lifter can do it's job 
in the active range.

Joel

steve korney wrote:
>
>
> It's unlikely that the push rod grew any... I would be suspect a valve 
> has concaved a little... How many hours on the engine and did it used 
> to run good...?
>
> Best... Steve
>
>
>
>
> ----Original Message Follows----
> From: Joel Smith <joels at austin.rr.com>
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Lycoming IO 360 C1C Valve Problem Question
> Date: Fri, 18 May 2007 00:02:21 -0500
>
> After all that noise, etc., looks like the problem is that the push rod
> is to long.
>
> Quite worrisome, makes me wonder how many others are wrong.
>