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| | | | Joined: Oct 2005 Posts: 29 'Bolter | | 'Bolter Joined: Oct 2005 Posts: 29 | I have access to a Detroit 6V53 for my 2-ton GMC 350; is this too much engine for the SM 420? | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | I would say so, but it would be more useful to get a closer ratio trans because of the narrow torque band of the DD. There are Clark OD 5 speeds that would be suitable. Or an NV-4500. You could also use a direct 5 speed and add a 6000 series Brownie that would give greater gear selection.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Oct 2005 Posts: 29 'Bolter | | 'Bolter Joined: Oct 2005 Posts: 29 | Thanks, Ed - I was actually thinking about an NV-4500 that would space things out a little more evenly - there are a fair number of them out there. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Part of your decision might be what your rear end ratio is and what you could easily change it to and use. What is the rear axle in it now? There are also 6 speeds out there.
Ed
Last edited by EdPruss; 03/23/2017 5:40 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Feb 2004 Posts: 29,771 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,771 | Most DD engines only have a 400 RPM torque band- - - -1750-2150 RPM. You'll need another gear ratio available anytime the RPM drops much below 1850-1900, as Detroits aren't famous for having much low-end torque. The term "Screamin' Jimmy" applies to the blower noise, and the fact that they run best just a few RPM below the point where the governor kicks in. A 10 or 13 speed Roadranger would be an ideal choice for a transmission.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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