| "K" Heads [message #319962] |
Tue, 04 July 2017 13:12  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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While doing some spark plug work on the coach this morning, I noticed my '75 455 (stock, un-rebuilt as far as I know) has "K" heads, not the "J" heads that are often spoken of here.
Are these virtually the same? Has my engine been replaced or messed with at some point?
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] "K" Heads [message #319964 is a reply to message #319962] |
Tue, 04 July 2017 13:30  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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K-a heads are from high performance 455 engines. Like W-30 spec, and 442's.
They were not fitted to the motor home, marine (except Crusader H.O.) or
agricultural applications, NORMALLY. But, all things are possible. The K-a
heads do not have hardened valve seats, but they have larger diameter
valves and ports. Better for high rpm applications, not so much for "stump
pullers" like our motor homes. They find their way into our coaches
occasionally by rebuilders. The Cutlass and 442 guys prize them quite
highly. Me, not so much. I prefer G or J heads. They have induction
hardened valve seats, a bit lower compression, and smaller ports. But all
of them are getting harder to find. EDELBROCK and a couple others make H.O.
heads from aluminum that will fit the 455. Last resort.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jul 4, 2017 11:13 AM, "Carl Stouffer" wrote:
> While doing some spark plug work on the coach this morning, I noticed my
> '75 455 (stock, un-rebuilt as far as I know) has "K" heads, not the "J"
> heads
> that are often spoken of here.
>
> Are these virtually the same? Has my engine been replaced or messed with
> at some point?
> --
> 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
>
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| Re: [GMCnet] "K" Heads [message #320031 is a reply to message #319967] |
Wed, 05 July 2017 18:59 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Carl S. wrote on Tue, 04 July 2017 13:35Even more curious is that the left bank has a "J" head on it. The right head must have been replaced at one time. It does explain why the right valve cover had only RTV on it and the left one had a gasket when I did valve cover gaskets some time back.
It also might explain why I seem to have a leaky valve or two on the right side. A leak down test will verify my suspicions on that. I plan to have my mechanic friend do one for me whenever he can get to it.
The coach failed emissions when I took it in yesterday. High on Hydrocarbons. The ignition all looks good except for one bad boot on the #7 plug wire. Maybe leaky exhaust valves?
My mechanic friend, Ron, said the HC failure wasn't high enough to indicate a burned valve. He thought the bad spark plug wire boot might be the reason for the high HC failure. Crossing my fingers.
Either way, I will need that J head sooner or later.
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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