| [GMCnet] More on final drive ratios [message #237976] |
Wed, 29 January 2014 15:57  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
|
Senior Member |
|
|
We finally headed south yesterday. Where we live we have to climb mountains in all directions anywhere from a mean climb of 1500 feet to around 4500 feet. With the new S@J engine (Spokane, WA), a 3.5 chain in the transmission and a 3.21 final drive our heavy 78 Royale did the climb over Siskiyou Pass (highest point on the I5) in third gear. Never saw less than 4" of vacuum or less than 50mph. Never felt or sounded strained. Going down the south side we stayed in third and only needed the brakes a few times. Both attributable to the relatively high compression of a new engine (still in breakin mode with just 1200 miles when we left home) and the gearing. While some may disagree, I think having the cam timing set 4 degrees advanced and the Patterson distributor set to 10 degrees static advance at 400rpm with the vacuum plugged both played a role as well.
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
541-592-5360
Cell 541-499-1027
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jerry & Sharon Work
78 Royale
Kerby, OR
|
|
|
|
| Re: [GMCnet] More on final drive ratios [message #238001 is a reply to message #237976] |
Wed, 29 January 2014 18:18  |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Jerry,
When you note "a 3.5 chain in the transmission" do you mean you have Manny's Power Drive installed? If yes with the 3.21 to 1 final
drive you've got a 3.67 ratio.
The cam set at 4° advance will have lowered your torque band (I couldn't say how much cause I'd be pulling the number out my nether
regions). What cam did you use?
The sheet Dick supplied with my distributor noted to set the advance at 12°
http://www.gmcmhphotos.com/photos/member-galleries/p32021-dick-paterson-s-distri.html
Which I set at a Slow Idle speed of 600 rpm Ref: X-7525 / Section 6M / ENGINE FUEL SYSTEM / Page 6M-23 / Figure 12 / Step 6.
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gerald Work
We finally headed south yesterday. Where we live we have to climb mountains in all directions anywhere from a mean climb of 1500
feet to around 4500 feet. With the new S@J engine (Spokane, WA), a 3.5 chain in the transmission and a 3.21 final drive our heavy
78 Royale did the climb over Siskiyou Pass (highest point on the I5) in third gear. Never saw less than 4" of vacuum or less than
50mph. Never felt or sounded strained. Going down the south side we stayed in third and only needed the brakes a few times. Both
attributable to the relatively high compression of a new engine (still in breakin mode with just 1200 miles when we left home) and
the gearing. While some may disagree, I think having the cam timing set 4 degrees advanced and the Patterson distributor set to 10
degrees static advance at 400rpm with the vacuum plugged both played a role as well.
Jerry
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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
|
|
|
|
| Re: [GMCnet] More on final drive ratios [message #238006 is a reply to message #237976] |
Wed, 29 January 2014 18:41 |
 |
SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
|
Senior Member |
|
|
That's one thing I didn't do, I was using the original dizzy, so I aligned the cloyes double roller straight up, and not one notch over as suggested for the HEI...of course I bought the HEI two months later...
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
