| 403 vs. 415 [message #301904] |
Thu, 09 June 2016 10:24  |
jor
Messages: 43
Registered: June 2016
Location: Tucson
Karma: 0
|
Member |
|
|
Another novice question: I understand GMC went to the 403 when they stopped production on the 455 big block. I have both on my potential buy list. I know the bore and stroke and torque figures are very different between these two engines but is one considered preferable over the other in the 26' GMC motorhome application? I note that many have changed their rear ends from 3.07 to 3.70 so let me stipulate that change in my question. Maybe this is a Ford-Chevy issue with personal preference being the definitive factor? I guess I am asking if one pulls a hill better than the other and if the higher revving small block is noisier or more prone to early death. Thanks.
jor
John O'Reilly
76 Eleganza II (quad bags, disc brakes w/ reaction arm. 3.70 gears, manny trans, headers, Patterson dist.)
Tucson, AZ
|
|
|
|
| Re: 403 vs. 415 [message #301905 is a reply to message #301904] |
Thu, 09 June 2016 11:28  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
|
Senior Member |
|
|
you are going to get all sorts of opinions.
my observation over the years of listening to others, is do not let the engine be the determining factor in what coach you buy. Condition is much more important!
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
|
|
|
|
| Re: [GMCnet] 403 vs. 415 [message #301906 is a reply to message #301904] |
Thu, 09 June 2016 11:25 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Both are good durable engines. The 455 is an older design, undersquare, and
more happy at a slightly lower rpm. The 403 is a newer design, oversquare,
and produces its maximum torque and horsepower at a higher rpm. They both
have the same longevity in motorhome use, lots of both engines go way over
100,000 miles in service which is a long way considering the loads and
infrequent use with long storage periods. I would not pull a good running
engine to replace it with the other one. A 403 with 3:70 final drive will
keep up with a 455 with 3:07 on hills with no problems. I would not rule
out either one, condition of the engine being equal. Just my professional
opinion based on many years of working on both engines.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, Jun 9, 2016 at 8:24 AM, John O'Reilly
wrote:
> Another novice question: I understand GMC went to the 403 when they
> stopped production on the 455 big block. I have both on my potential buy
> list. I
> know the bore and stroke and torque figures are very different between
> these two engines but is one considered preferable over the other in the 26'
> GMC motorhome application? I note that many have changed their rear ends
> from 3.07 to 3.70 so let me stipulate that change in my question. Maybe this
> is a Ford-Chevy issue with personal preference being the definitive
> factor? I guess I am asking if one pulls a hill better than the other and
> if the
> higher revving small block is noisier or more prone to early death. Thanks.
> jor
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
|
|
| Re: 403 vs. 415 [message #301910 is a reply to message #301904] |
Thu, 09 June 2016 12:15 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Empirically, the lighter 23' with a 455 and 3.07 gearing pulls hills without a lot of fanfare, but may require you to stuff it in S to keep the engine speed up. If mine falls below about 45 per, I downshift it - this only happens when I have to slow for traffic on the hills I cross. My 26' with 3.7 gearing scoots over them, no downshift required. It also uses substantially more fuel.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
| Re: [GMCnet] 403 vs. 415 [message #301911 is a reply to message #301904] |
Thu, 09 June 2016 12:22 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
|
Senior Member |
|
|
John,
From experience from shops like MGM-GMC, Grandview, and Jim Hupy, they will
tell you that the 3.70 will make performance better.
I'm sure we can discuss the longevity issue, but were not turning over that
many RPM and besides , lugging a engine at low rpm has is detrimental
issues.
On Thu, Jun 9, 2016 at 8:24 AM, John O'Reilly
wrote:
> Another novice question: I understand GMC went to the 403 when they
> stopped production on the 455 big block. I have both on my potential buy
> list. I
> know the bore and stroke and torque figures are very different between
> these two engines but is one considered preferable over the other in the 26'
> GMC motorhome application? I note that many have changed their rear ends
> from 3.07 to 3.70 so let me stipulate that change in my question. Maybe this
> is a Ford-Chevy issue with personal preference being the definitive
> factor? I guess I am asking if one pulls a hill better than the other and
> if the
> higher revving small block is noisier or more prone to early death. Thanks.
> jor
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
|
|
|
|
| Re: [GMCnet] 403 vs. 415 [message #301930 is a reply to message #301911] |
Thu, 09 June 2016 20:59 |
jor
Messages: 43
Registered: June 2016
Location: Tucson
Karma: 0
|
Member |
|
|
Thanks to all for the input. Sounds like it's all in the gearing. Hope I find one with the final drive upgrade.
jor
John O'Reilly
76 Eleganza II (quad bags, disc brakes w/ reaction arm. 3.70 gears, manny trans, headers, Patterson dist.)
Tucson, AZ
[Updated on: Thu, 09 June 2016 21:00] Report message to a moderator |
|
|
|
GMCforum
Search
Help
Register
Login
Home
