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| Mismatched Heads... Again [message #322700] |
Sat, 26 August 2017 18:43  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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About a month ago, I mentioned that I had discovered that my '75 455 had a J head on one side and a K head on the other side. The K head had a badly burnt exhaust valve and needed to be replaced/repaired. For lack of a better option, I ended up getting a pair of K heads reconditioned and had them installed by my very good, trusted mechanic. I feel kind of wimpy for not doing the job myself, since I know several of you who wouldn't hesitate to do a valve job who are 10 - 15 years older than I am, but I am also not retired and had time restraints which made it more sensible to hire out the job.
The weird thing is that as far as I knew, the engine on this coach was unmolested. Although the heads were different castings with different size intake valves, they were painted the exact same color and both had the steel shim OEM type head gaskets under them.
Just curious to see if anyone has ever run into something like this before or if any of you GM guys have ever heard of anything coming out of the factory like that.
http://www.gmcmhphotos.com/photos/misc-gmc/p63626-mismatched-heads.html
http://www.gmcmhphotos.com/photos/misc-gmc/p63629-p1020594.html
http://www.gmcmhphotos.com/photos/misc-gmc/p63629-p1020594.html
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[Updated on: Sat, 26 August 2017 20:27] Report message to a moderator |
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| Re: [GMCnet] Mismatched Heads Again [message #322709 is a reply to message #322700] |
Sat, 26 August 2017 22:34  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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If your going to do heads, majority of the time your valve guides will be
worn so to replace the guides is not that simple unless you have the tools
in your shop.
Also check the spring tensions with a tool.
Oh, heads should be magnafluxed as there are always chance of cracks.
On Sat, Aug 26, 2017 at 4:43 PM, Carl Stouffer wrote:
> About a month ago, I mentioned that I had discovered that my '75 455 had a
> J head on one side and a K head on the other side. The K head had a badly
> burnt exhaust valve and needed to be replaced/repaired. For lack of a
> better option, I ended up getting a pair of K heads reconditioned and had
> them
> installed by my very good, trusted mechanic. I feel kind of wimpy for not
> doing the job myself, since I know several of you who wouldn't hesitate to
> do a valve job who are 10 - 15 years older than I am, but I am also not
> retired and had time restraints which made it more sensible to hire out the
> job.
>
> The weird thing is that as far as I knew, the engine on this coach was
> unmolested. Although the heads were different castings with different size
> intake valves, they were painted the exact same color and both had the
> steel shim OEM type head gaskets under them.
>
> Just curious to see if anyone has ever run into something like this before
> or if any of you GM guys have ever heard of anything coming out of the
> factory like that.
>
> http://www.gmcmhphotos.com/photos/misc-gmc/p63626-mismatched-heads.html
>
> http://www.gmcmhphotos.com/photos/misc-gmc/p63629-p1020594.html
>
> http://www.gmcmhphotos.com/photos/misc-gmc/p63629-p1020594.html
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,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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| Re: [GMCnet] Mismatched Heads Again [message #322711 is a reply to message #322709] |
Sat, 26 August 2017 22:48 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Jim, These were good cores with hardened valve seats. Larry's engine & Marine (Tucson) put them together with new SS valves, guides, and springs. They had been milled about .010. The new gaskets were thicker than that plus the stock metal gaskets.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Mismatched Heads Again [message #322712 is a reply to message #322711] |
Sat, 26 August 2017 22:56 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Ok, Most machine shops have a low paid young guy doing the heads. I always
request that the usual tech work on it and pay accordingly.
On Sat, Aug 26, 2017 at 8:48 PM, Carl Stouffer wrote:
> Jim, These were good cores with hardened valve seats. Larry's engine &
> Marine (Tucson) put them together with new SS valves, guides, and springs.
> They had been milled about .010. The new gaskets were thicker than that
> plus the stock metal gaskets.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Mismatched Heads... Again [message #322717 is a reply to message #322700] |
Sun, 27 August 2017 00:38 |
mrgmc3
Messages: 210
Registered: September 2013
Location: W Washington
Karma: 2
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Senior Member |
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Carl S. wrote on Sat, 26 August 2017 18:43
The weird thing is that as far as I knew, the engine on this coach was unmolested. Although the heads were different castings with different size intake valves, they were painted the exact same color and both had the steel shim OEM type head gaskets under them.
Just curious to see if anyone has ever run into something like this before or if any of you GM guys have ever heard of anything coming out of the factory like that.
If the K and J heads were both available during your model year I'd say it is a distinct but remote possibility. Each engine would have had a manifest that describes content for that particular engine as it was assembled, but errors can happen. The castings look the same except for the big ID letters (and incidentally larger than the casting ID on Chev, Buick, Pontiac of the era), so the operator grabbing the wrong head is a possibility. I've never been in the Lansing engine plant, but in Flint's plant 36 each head was installed by an operator on opposite sides of the engine so a single operator did not do both installations. Inspectors are supposed to catch this further down the line, but this may be that rare occurrence where multiple errors occurred. Once the completed engine was shipped from Lansing to Pontiac it would be unlikely that anyone would notice. Your evidence of factory paint and gaskets would seem to confirm this error.
Chris Geils - Twin Cities / W Wa
1978 26' Kingsley w/ very few mods; PD9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, Alcoas, 54k mi
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