<VV> 110 vs 140 Heads

[Frank DuVal]

I've worked on enough small valve Corvair heads with dropped seats that 
I no longer consider them less prone than 140 heads.

Hot is hot, whether from running hard racing, climbing hills, 
pre-heating (A/C condenser) or air flow restrictions.

I think the 140s suffered first because of the larger opening and 
spirited driving. The same expansion rate would open the larger hole 
larger than a smaller hole, and conversely shrink the large seat more 
than a small seat (% of expansion vs thousandths of expansion). Since 
the actual size of the interferrence fit is the same for both size 
seats. But, this is just my opinion. Now, after so many heat cycles, 
they all are suspect.

Frank DuVal


On 3/24/2014 8:37 PM, MarK Durham wrote:
> Its just that the small valve heads have a lot less problem with dropped
> seats than the hotter running 140 heads. I do not know the dynamics of why
> that is other than the 140 heads have a larger intake runner and larger
> valves and larger exhaust tubes so they can flow more air/fuel mixture and
> produce more power and the result is its easier to put them over the edge
> when less than ideal hot conditions exist.  Mark Durham Hauser Idaho
> On Mar 24, 2014 3:07 PM, "corvairduval at cox.net" <corvairduval at cox.net>
> wrote:
>
>> I undrstand the flow of the 95 HP heads and better low end torque, but how
>> does faster air fix the issue of valve seats falling out from cold air
>> rushing through hot seats?
>>
>> Frank DuVal
>>
>>
>>
>> Original email:
>> -----------------
>> From: MarK Durham 62vair at gmail.com
>> Date: Mon, 24 Mar 2014 14:06:04 -0700
>> To: hmlinc at sbcglobal.net, virtualvairs at corvair.org, maxspeed at juno.com
>> Subject: Re: <VV> 110 vs 140 Heads
>>
>>
>> To avoid the valve seat issue, take a 95 head and add the 4x1 Clarks
>> conversion. The smaller intake runners flow a faster air mix than the 140
>> heads that gives better low end torque. Mark Durham Hauser Idaho.