<VV> Valve Seats - was Corvairs

[J R Read_HML]

Just in case I want to find this later.
Later, JR

----- Original Message ----- 
From: <jvhroberts at aol.com>
To: <shortle556 at earthlink.net>; <virtualvairs at corvair.org>
Sent: Monday, May 10, 2010 9:47 AM
Subject: Re: <VV> Corvairs


>
> In my EVER so humble opinion (and you ALL know how humble I truly am!), 
> here's what I see as the list of issues with Corvair valve seats. 
> Obviously, people like Warren have their own ideas, and their solutions do 
> work, so, here goes...
>
> 1. Insufficient cooling. Obviously, since aluminum has a much higher CTE 
> than steel, the hotter things get, the looser the fit.
> 2. Seats aren't deep/wide enough. The more deeply seated, and the thicker 
> the cross section, not only do you get a tighter fit, but the temperature 
> mismatch between the seat and the head will be smaller.
> 3. Seats not made of the best stuff. There are manganese steels and 
> aluminum bronzes which a far closer to the CTE of aluminum than the OE 
> seat material.
> 4. Seats not well retained. Now this one is open as to the best way to do 
> this. But a step machined on the OD of the top of the seat allows the head 
> material to be staked well into the seat. Or threaded seats. Or setscrews 
> (not my fave). Or if someone had a huge budget, electron beam welding of 
> the seats into place. Yes, you CAN weld steel to aluminum by this method. 
> There are also brazing alloys suitable for this as well. Or some other 
> method I haven't thought of yet...
> 5. Engine not properly tuned/syncronized. Detonation, one side running 
> hotter than the other, too much retard, et al, all can exacerbate the 
> problem.
> 6. Valve train not properly set up. When the valves clatter like hell, 
> it's a sign that the valves are slamming into the seat, as compared to 
> landing gently, as designed. This will hammer the seats loose more than 
> one might think!
>
> Now, as far as what to do about this, my best idea is to pull the seats, 
> weld 'em up, and put in nice deep ones. Also, make sure the guides are in 
> good shape.
>
> So, there's my start on this thread!!
>
>
>
> John Roberts
>
>
>
>
> -----Original Message-----
> From: shortle <shortle556 at earthlink.net>
> To: virtualvairs at corvair.org <virtualvairs at corvair.org>
> Sent: Mon, May 10, 2010 10:18 am
> Subject: <VV> Corvairs
>
>
> My nemesis with Corvairs (lately) seems to be with their valve seats 
> coming
> loose from the heads. This has happened to me twice in about 25,000 miles.
> Timothy Shortle in Durango Colorado