[AT] [External] Re: Valve Seat Inserts

[Gunnells, Brad R]

Wasn't there something also with the change from leaded to unleaded fuels? For some reason I thought manufacturers started putting harder valve seats in later model engines due to the limiting of lead. I could be way off here but I thought I'd heard about that back in my dirt track racing days.

Brad

On 12/3/20, 12:57 AM, "AT on behalf of Dean VP" <at-bounces at lists.antique-tractor.com on behalf of deanvp at att.net> wrote:

    Steve,

    AHA,, I completely overlooked they were two different parts. Now the lights
    go on.  Now I understand. The valve seat might be damaged but the guide may
    still be good or vice versa.   As I recall that was more of a problem in the
    40's and 50's than it is now.

    Dean VP
    Apache Junction, AZ

    -----Original Message-----
    From: AT <at-bounces at lists.antique-tractor.com> On Behalf Of Steve W.
    Sent: Wednesday, December 2, 2020 11:38 PM
    To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
    Subject: Re: [AT] Valve Seat Inserts

    Dean VP wrote:
    > Found a term in this company's price list that rings some memories
    > but really hazy ones.    Could someone explain when and why "Valve
    > Seat Inserts"  are used rather than replacing the whole valve guide?
    > Yes, they are a little less expensive but not that much  Please 
    > refresh my hazy memory from the 50's.
    > 
    > 
    > 
    > Dean VP
    > 

    Different parts. The valve guide holds the valve stem and keeps it in
    position. The valve seat is the ground part of the port in the head that the
    valve face seals against. The reason for the inserts are a few, one is that
    you might have a head with damaged or eroded seats and the valves won't
    seal. You machine out the worn/damaged area, press in the inserts and either
    peen the edge or more commonly you bore the area for the seat with a step so
    the seat locks into the head, to install you freeze the insert and heat up
    the head. Then the two parts lock together as the temperatures normalize.
    Have done both and prefer the second option.

    --
    Steve W.
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