Home » Public Forums » GMCnet » [GMCnet] "C" Heads
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| Re: [GMCnet] "C" Heads [message #59936 is a reply to message #59935] |
Mon, 12 October 2009 23:33   |
Tin Gerbil
Messages: 236
Registered: October 2006
Location: Vancouver Island, B.C.
Karma: 0
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Senior Member |
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Terry;
This is called a "go fast" head VERY VALUABLE TO THE STREET RACERS;
C '67 - '69 425 & 455 80cc 394548 A/C '68 H/O's. Toro's and
442's got big valves. Rumored to flow the best of all BB heads.
This is what we want for torque in a coach;
J '73 - '76 455 80,82cc 411783 All 445's. 'Smog heads',
The intake manifold has large cross section runners, not good for low
end torque.
SOURCE;
http://www.442.com/oldsfaq/ofhed.htm#Heads%201964%20-%201990
Gordon
Terrance Boyd wrote:
> Today I was at a rural "Mens Mall". They have a1968 Toronado with "C"
> heads. I'm looking for opinions about these heads, also about the intake
> manifold.
> Any advice will be appreciated.
> Thank You
> Terry
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Gordon
'74 Canyon Lands "Tin Gerbil"
Vancouver Island, B.C.
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| Re: [GMCnet] "C" Heads [message #59947 is a reply to message #59936] |
Tue, 13 October 2009 06:39 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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Steve F. can really give you the rodders rundown on heads but in the real world all you say is correct, you really want to run "J" or maybe "G" heads on a GMC. You can save money cause the rodders don;t want smogger heads. Heck, I've had them give them to me! There is no downside to them in our application, the more important issue is the valve work that you do to them. There are tons of things there but in the end, a good strong set of valves set properly, new rockers, steel bridges and added adjustment on the valve train can be done several ways. All that stuff really makes the heads "sing".
Don;t get all hot and bothered on "C" heads, if you have a set make some moola, find a speed freak and sell them to him. You'll make a buddy for life,
Jim Bounds
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----- Original Message ----
From: Gordon <wizwing@telus.net>
To: gmclist@temp.gmcnet.org
Sent: Tue, October 13, 2009 12:33:16 AM
Subject: Re: [GMCnet] "C" Heads
Terry;
This is called a "go fast" head VERY VALUABLE TO THE STREET RACERS;
C '67 - '69 425 & 455 80cc 394548 A/C '68 H/O's. Toro's and
442's got big valves. Rumored to flow the best of all BB heads.
This is what we want for torque in a coach;
J '73 - '76 455 80,82cc 411783 All 445's. 'Smog heads',
The intake manifold has large cross section runners, not good for low
end torque.
SOURCE;
http://www.442.com/oldsfaq/ofhed.htm#Heads%201964%20-%201990
Gordon
Terrance Boyd wrote:
> Today I was at a rural "Mens Mall". They have a1968 Toronado with "C"
> heads. I'm looking for opinions about these heads, also about the intake
> manifold.
> Any advice will be appreciated.
> Thank You
> Terry
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http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] "C" Heads [message #59949 is a reply to message #59947] |
Tue, 13 October 2009 07:36 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Terry,
Unfortunately Steve Ferguson has left the GMC net for personal reasons so
you won't see any responses from him.
Regards,
Rob Mueller
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
'75 Avion - USA - The Parts Coach TZE 365V100324
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Jim Bounds
Sent: Tuesday, October 13, 2009 10:40 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] "C" Heads
Steve F. can really give you the rodders rundown on heads but in the real
world all you say is correct, you really want to run "J" or maybe "G" heads
on a GMC. You can save money cause the rodders don;t want smogger heads.
Heck, I've had them give them to me! There is no downside to them in our
application, the more important issue is the valve work that you do to
them. There are tons of things there but in the end, a good strong set of
valves set properly, new rockers, steel bridges and added adjustment on the
valve train can be done several ways. All that stuff really makes the heads
"sing".
Don;t get all hot and bothered on "C" heads, if you have a set make some
moola, find a speed freak and sell them to him. You'll make a buddy for
life,
Jim Bounds
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http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] "C" Heads [message #59954 is a reply to message #59949] |
Tue, 13 October 2009 08:27 |
Gary Casey
Messages: 448
Registered: September 2009
Karma: 0
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Senior Member |
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It looks like I'm about to do a valve job on mine, so I'm curious, what are all those things that can make the heads "sing"? What are "stronger" valves? New rockers are better than old ones? I assume that as they wear the hydraulic lifter travel will get to the limit, but what else? Steel bridges? Are these the bridges that double as bearings for the rockers? I assume the standard springs are good for maybe 4,000 rpm and that's about all? does anyone put restrictors in the crossover passages to reduce the intake manifold temperature? I already have headers, so there is no heat riser valve.
Gary
________________________________
...There is no downside to them in our
application, the more important issue is the valve work that you do to
them. There are tons of things there but in the end, a good strong set of
valves set properly, new rockers, steel bridges and added adjustment on the
valve train can be done several ways. All that stuff really makes the heads
"sing".
Jim Bounds
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] "C" Heads [message #59956 is a reply to message #59954] |
Tue, 13 October 2009 08:38 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Gary,
Comp Cams offers a set of adjustable rockers that bolt on. SteveF. Bob Drewes and a few others have had good reports on these.
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4771
There are also some new, improved material rockers for just OIM replacment. Again, Steve Ferguson has them identified on his album of engine rebuilds.
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3100
Blocking the crossovers is very desirable. Dick Paterson sells a gasket set with stainless steel block off plates. His gaskets are available from JimK, also.
Dennis
Dennis Sexton
73 GMC
Germantown, TN
USA
-----Original Message-----
From: Gary Casey <casey.gary@yahoo.com>
To: gmclist@temp.gmcnet.org
Sent: Tue, Oct 13, 2009 8:27 am
Subject: Re: [GMCnet] "C" Heads
It looks like I'm about to do a valve job on mine, so I'm curious, what are all
those things that can make the heads "sing"? What are "stronger" valves? New
rockers are better than old ones? I assume that as they wear the hydraulic
lifter travel will get to the limit, but what else? Steel bridges? Are these
the bridges that double as bearings for the rockers? I assume the standard
springs are good for maybe 4,000 rpm and that's about all? does anyone put
restrictors in the crossover passages to reduce the intake manifold temperature?
I already have headers, so there is no heat riser valve.
Gary
________________________________
...There is no downside to them in our
application, the more important issue is the valve work that you do to
them. There are tons of things there but in the end, a good strong set of
valves set properly, new rockers, steel bridges and added adjustment on the
valve train can be done several ways. All that stuff really makes the heads
"sing".
Jim Bounds
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Dennis S
73 Painted Desert 230
Memphis TN Metro
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