<VV> 110 vs 140 Heads

Wed Mar 26 09:41:17 EDT 2014

It's still about 1/3 less than that of aluminum, not much more than steel. The big plus is superior thermal conductivity, which means the seats run a bit hotter, which helps keep them closer to the same expansion rate as the heads. Not to mention it keeps the valves cooler, since about 75% of the heat flow out of the valve is through the seat. 

There's a myth about the toxicity of beryllium alloys. The parts are not toxic at all, it's the dust from machining them that's the problem. So, grind them with care, and with lots of coolant. The only known route of ingestion is inhalation of the dust. I assume no one is eating the dust and shavings!! 

John Roberts

-----Original Message-----
From: Paul Fox <paulvair at yahoo.com>
To: jvhroberts <jvhroberts at aol.com>; 62vair <62vair at gmail.com>; mmccrae6 <mmccrae6 at cox.net>
Cc: virtualvairs <virtualvairs at corvair.org>; corvairduval <corvairduval at cox.net>
Sent: Wed, Mar 26, 2014 8:08 am
Subject: Re: <VV> 110 vs 140 Heads

Some times you'll see beryllium copper alloy seats. I have a set of race heads like that. I've been told they'll stay put because they expand and contract at the same rate as the aluminum. The problem is it's poisonous and must be handled as such.
Paul Fox

  On Tuesday, March 25, 2014 9:02 PM, "jvhroberts at aol.com" <jvhroberts at aol.com> wrote:

 Interesting comment, since Briggs and Stratton were the ones who did a lot of the design work on our engines. 

John Roberts

-----Original Message-----
From: MarK Durham <62vair at gmail.com>
To: Mike McCrae <mmccrae6 at cox.net>
Cc: jvhroberts <jvhroberts at aol.com>; virtualvairs <virtualvairs at corvair.org>; corvairduval <corvairduval at cox.net>
Sent: Tue, Mar 25, 2014 2:02 pm
Subject: Re: <VV> 110 vs 140 Heads

That is incorrect. Some  radial engine designs used screw in seats but most modern air cooled Lycoming and Continental engine designs since the 1960's do not. They are an interference fit just like the Corvair. Where do you think GM got the data from? Aviation. Mark Durham Hauser Idaho
On Mar 25, 2014 9:22 AM, "Mike McCrae" <mmccrae6 at cox.net> wrote:

Yes....but most aircraft seats screw in, and are then pinned....they cant drop out.

Mike McCrae

-----Original Message----- From: jvhroberts at aol.com
Sent: Tuesday, March 25, 2014 7:53 AM
To: 62vair at gmail.com ; corvairduval at cox.net
Cc: virtualvairs at corvair.org
Subject: Re:  110 vs 140 Heads

I always wondered about a different alloy for the seats.
Aluminum has a CTE of about 13 ppm/F.
There's a bunch of steel alloys, such as high manganese steel, molybdenum steel alloys, certain types of hardenable cast iron and some cast stainless alloys that just about match this in the temperature range of interest. I think aircraft engines have taken this approack.
Anyway, something to think about. Seats are simple parts to machine, from a CNC standpoint.

John Roberts

-----Original Message-----
From: MarK Durham <62vair at gmail.com>
To: Frank DuVal <corvairduval at cox.net>
Cc: virtualvairs <virtualvairs at corvair.org>
Sent: Tue, Mar 25, 2014 9:41 am
Subject: Re: <VV> 110 vs 140 Heads

Yes, everything is getting old. That has to be a big factor. And you are
correct, heat is heat, and small valve heads will experience the same
issues if they get warn enough, its just harder to get them there in
average coupé or sedan driving.  Since my heads only have 72k mikes on
them, and I still have the original seats, I am probably OK. I only drive
the car 1500 Miles a year. Mark Durham Hauser Idaho.
On Mar 24, 2014 9:30 PM, "Frank DuVal" <corvairduval at cox.net> wrote:

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