Home » Public Forums » GMCnet » Oldsmobile 455 heads G vs J
| Re: [GMCnet] Oldsmobile 455 heads G vs J [message #324416 is a reply to message #324404] |
Wed, 27 September 2017 11:31   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
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Senior Member |
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Emery, just a bit of what I know about Olds cylinder heads.
1. During the production run of our GMC coaches there were only 2 heads
listed as being produced (manufactured) in the 1973 - 1976 time period and
that I know for sure are induction hardened. They were as follows:
A. 1973 - 1976 "J" heads made for 455 cubic inch engines, 82 cc
combustion chambers. Known as "Smogger Heads". Racers don't like them
particularly because of the big combustion chambers and smaller valves. We
like them for the motor homes because they make good torque at the RPMs
that we run our coaches, plus they are regular fuel, and have hardened
valve seats.
B. 1973 - 1976 "K A" heads. 455 cubic inch, Marine, Irrigation,
Industrial, Some motor homes, W/30, Toronado, 442 4 speed cars, Big Valves
and ports. 80cc chambers. Most were induction hardened, and the H/O
versions had strong valve springs and used a bit different rocker arms and
camshafts that were not suitable for motorhome use.
Other heads that can be used with modifications like hardened valve seats
and different exhaust valves, springs and keepers that were manufactured
before 1973 were the the "G" heads, manufactured in 1971, and "E" heads
made 1968 - 1970. These are getting scarce, and frequently are in poor
shape, due to cracks, stripped bolt holes, etc.
There are still a couple of aluminum heads manufactured. Mondello and
Edelbrock both show them in their catalog. I don't know much about them.
There is a whole lot more info out there, and much of it centers upon
"numbers matching" stuff for collector car guys that want the right date
codes for when their cars were produced. That stuff means nothing to us,
and clogs up my memory cells, so I try to not remember it.
Just what I know. Dick Paterson's sources may differ a bit from this. He is
an encyclopedia of Olds data.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Tue, Sep 26, 2017 at 7:34 PM, Carl Stouffer wrote:
> Apparently Toro and 442 G heads have the big valves. Also it seems like
> the G heads have slightly less restrictive exhaust ports than the J heads.
>
>
>
> --
> 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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