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[GMCnet] Hardened valve seats [message #283242]

Sun, 26 July 2015 22:10

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

WARNING:

Someone recently posted that all 455 and 403 heads had hardened seats so it was not necessary to use hardened inserts.
I cannot find that email right now but it was just a few days ago.

Often people have replaced the heads and not all have hardened seats

According to information that Dick Paterson published a few years back here is the head information.

Those with “soft” seal areas that require hardened exhaust seat inserts:

455 1966 B
455 67-69 C
455 68-69 D
455 68-70 E
455 1970 F
all of the above were for leaded fuels

Those with hardened seal areas that don’t require inserts:

455 1971 H
455 71-72 G
455 1972 Ga
455 71-72 J
455 73-76 (Cutlass) K
455 73-76 (Marine / Irrigation) K

403 77-79 4A

These all were for unleaded fuels.

Note that this information was for all applications of the 455, not just the GMC motorhome.

Emery Stora
77 Kingsley
Frederick, CO
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Re: [GMCnet] Hardened valve seats [message #283255 is a reply to message #283242]

Mon, 27 July 2015 07:40

winter

Messages: 247
Registered: September 2007
Location: MPLS MN

Karma: 0

Senior Member

I thought the rule of thumb was anything after 71 was hardened.

Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota

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Re: [GMCnet] Hardened valve seats [message #283261 is a reply to message #283255]

Mon, 27 July 2015 08:42

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

When I said that other people may have changed the heads I meant that some of the heads are older. You can’t go by the year of the motorhome but must check the head number that is cast into it.

Emery Stora

> On Jul 27, 2015, at 6:40 AM, jerrod winter wrote:
>
> I thought the rule of thumb was anything after 71 was hardened.
> --
> Jerrod Winter
> 1977 Palm Beach
> Green Jelly Bean
> Twin Cities, Minnesota
>

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Re: [GMCnet] Hardened valve seats [message #283272 is a reply to message #283242]

Mon, 27 July 2015 10:35

winter

Messages: 247
Registered: September 2007
Location: MPLS MN

Karma: 0

Senior Member

That's right. Never assume anything.

My thought was, for most GM engines, hardened seats were starting to show up around 71. Depends on the engine though.

Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota

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Re: [GMCnet] Hardened valve seats [message #283278 is a reply to message #283272]

Mon, 27 July 2015 10:58

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

I think you are right on with the 1971 number. Hard to
Believe it's been 43 years ago now.

Emery Stora
77 Kingsley
Frederick, CO

> On Jul 27, 2015, at 9:35 AM, jerrod winter wrote:
>
> That's right. Never assume anything.
>
> My thought was, for most GM engines, hardened seats were starting to show up around 71. Depends on the engine though.
> --
> Jerrod Winter
> 1977 Palm Beach
> Green Jelly Bean
> Twin Cities, Minnesota
>
> _______________________________________________
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Re: [GMCnet] Hardened valve seats [message #283287 is a reply to message #283278]

Mon, 27 July 2015 11:59

Loffen

Messages: 1087
Registered: August 2013
Location: Norway

Karma: 1

Senior Member

Even if it has a hardened seat you should be a little bit careful, they are flame hardened so just one valve seat to valve grind and no more unleaded fuel for you Wink

1973 23' # 1848 Sky Blue Glacier called Baby Blue and a 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Green, And sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt trøbbel in Norway

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Re: [GMCnet] Hardened valve seats [message #283299 is a reply to message #283287]

Mon, 27 July 2015 14:19

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Like Espen says, the seats are induction hardened on the surface only. One
valve seat grind and you are through most of it. Next time it is time for
installed hardened valve seats. That is best accomplished by a automotive
machine shop that knows their stuff. No 454 Chevrolet valve seats here.
Olds only.
Jim Hupy
On Jul 27, 2015 11:52 AM, "Espen Heitmann" wrote:

> Even if it has a hardened seat you should be a little bit careful, they
> are flame hardened so just one valve seat to valve grind and no more
> unleaded
> fuel for you ;)
> --
> 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Mean Green Machine,
> And just sold my 1973 26'-2 # 581 White Canyon lands under the name
> Dobbelt trøbbel
> in Norway
>
>
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Re: [GMCnet] Hardened valve seats [message #283313 is a reply to message #283242]

Mon, 27 July 2015 15:56

winter

Messages: 247
Registered: September 2007
Location: MPLS MN

Karma: 0

Senior Member

Should the exhaust valve be changed to something such as stainless at the same time. Newer technology available since then?

Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota

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Re: [GMCnet] Hardened valve seats [message #283315 is a reply to message #283313]

Mon, 27 July 2015 16:11

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

Jim H mentioned not to use Chevrolet seats. He was assuming that we know
that the Chevy. seats are taller and most machine shops are not aware and
cut into the water jacket.

On Mon, Jul 27, 2015 at 1:56 PM, jerrod winter wrote:

> Should the exhaust valve be changed to something such as stainless at the
> same time. Newer technology available since then?
> --
> Jerrod Winter
> 1977 Palm Beach
> Green Jelly Bean
> Twin Cities, Minnesota
>
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

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