| [GMCnet] More on cams [message #278396] |
Mon, 25 May 2015 18:10  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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With two coaches, each set up with the same new engines, tires, trans and final drive it is easy to detect even small differences in components. The engine in the Royale was built with what the builder identified as an RV cam set 4 degrees advanced (cam timing, not distribution timing) while the Engine in the Clasco from the same engine builder used what the builder insisted was the same cam GM used in the motorhome 455s to begin with. It was also set 4 degrees advanced. I do not have detailed specs on either.
From the drivers seat the Royale seems stronger on the hills as determined by a number of trips over the same hills in both coaches. The Royale is fully broken in while the Clasco has a ways to go to catch up in terms of break in miles so that plays some role, but My guess at this point is the Royale will always be a bit stronger on the hills no matter how many miles we rack up on these two coaches.
Both are equally pleasant to drive and both climb the hills easily in third gear, it is just that the Royale seems less labored doing so. I have not confirmed that they are both set to the same distributor timing, but I think they are close. The,bottom line is that whatever GM used originally in the motorhome 455s, it apparently can be bested a bit, but not a lot, by today's RV specific cam grinds.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] More on cams [message #278415 is a reply to message #278396] |
Mon, 25 May 2015 22:52  |
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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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G'day,
According to Dick Patterson the cam to use is: COMP Cams DEH 255 42-207-4 cam
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1178&sb=2
Regards,
Rob
-----Original Message-----
From: Gerald Work
With two coaches, each set up with the same new engines, tires, trans and final drive it is easy to detect even small differences in
components. The engine in the Royale was built with what the builder identified as an RV cam set 4 degrees advanced (cam timing,
not distribution timing) while the Engine in the Clasco from the same engine builder used what the builder insisted was the same cam
GM used in the motorhome 455s to begin with. It was also set 4 degrees advanced. I do not have detailed specs on either.
From the drivers seat the Royale seems stronger on the hills as determined by a number of trips over the same hills in both coaches.
The Royale is fully broken in while the Clasco has a ways to go to catch up in terms of break in miles so that plays some role, but
My guess at this point is the Royale will always be a bit stronger on the hills no matter how many miles we rack up on these two
coaches.
Both are equally pleasant to drive and both climb the hills easily in third gear, it is just that the Royale seems less labored
doing so. I have not confirmed that they are both set to the same distributor timing, but I think they are close. The, bottom line
is that whatever GM used originally in the motorhome 455s, it apparently can be bested a bit, but not a lot, by today's RV specific
cam grinds.
Jerry
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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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