[SEL] The McVickerish Engine

[Elden DuRand]

Steve:

If you are correct about the exhaust port at the end of the valve piston's stroke, it makes sense.  That port would allow overpressure in that cylinder to be released and the valve piston would retreat a short distance toward the head of the valve cylinder to close the port and hold there until the power piston skirt cleared the port to let the pressure escape.

In your engine, the valve cylinder overpressure is routed to the power cylinder exhaust port.  If I end-up drilling the small hole to let out the oil/crud, it will be in the same position and, if needed, I can simply increase the hole size a little and either let it "spit" directly into the atmosphere or I could plumb it to the exhaust pipe.

This would alleviate some of the hammering of the exhaust valve piston due to overpressure, allowing the exhaust valve to "overopen" due to momentum of the valve piston and valve gear, then settle back to a smaller opening for the rest of the stroke.

Ingenious guy, that McVicker!

Take care - Elden DuRand
edurand at mchsi.com
http://www.oldengine.org/members/durand 

> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com]On
>  Behalf Of Steve
> Royster
> Sent: Monday, March 22, 2010 07:24 PM
> To: The SEL email discussion list
> Subject: Re: [SEL] The McVickerish Engine
> 
> 
> 
> Hi Elden, I believe this is only a small port to 
> relieve the pressure from the lower exhaust valve 
> piston, I think the small piston  uncovers  the 
> port in the valve cage at the end of it's 
> downward travel and this small port lets the 
> small amount of pressure and  unburned fuel and 
> oil blow out the pipe to the man exhaust pipe. If 
> you hold your finger over the port when it fires 
> there is very little pressure coming from it.  I 
> have to take the cage off and replace the bolts 
> with studs soon and I'll take pics for you.   Steve
>  
> > From: edurand at mchsi.com
> > To: sel at lists.stationary-engine.com
> > Date: Mon, 22 Mar 2010 19:15:45 -0500
> > Subject: Re: [SEL] The McVickerish Engine
> > 
> > Steve:
> > 
> > I was looking at the photos again. Is the pipe 
> with the union on it that goes to the exhaust 
> port an actual ported exhaust setup? If so, the 
> exhaust valve actuating port must be ahead of the 
> exhaust relief port.
> > 
> > Disorganized (disordered?) minds need to know. :-)
> > 
> > Take care - Elden
> > edurand at mchsi.com
> > http://www.oldengine.org/members/durand 
> > 
> > 
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