| [GMCnet] Hardened valve seats [message #283242] |
Sun, 26 July 2015 22:10  |
emerystora
Messages: 4442
Registered: January 2004
Karma:
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Senior Member |
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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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