| 403 car vs. motorhome engine [message #189467] |
Wed, 07 November 2012 12:55  |
Galen
Messages: 146
Registered: November 2011
Location: New Virginia, IA
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I've searched the forum and around online, and while I can find references to differences between the auto version of the 403 and the GMC motorhome version, would anyone mind provding a short rundown on the differences, and if there is any way of identifying if an engine is an original motorhome engine? Thanks,
Galen
Galen Briggs
New Virginia, Iowa
1978 Palm Beach
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| Re: 403 car vs. motorhome engine [message #189504 is a reply to message #189467] |
Wed, 07 November 2012 18:45  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Sir: There isn`t much info about the 403 motorhome only engine. The parts book lists 2 403s for the MH one probably Calif or maybe one is the rare (2500) "a" casting which has solid main webs (561032 & 561033). It will have the toro oil pan & pickup, and will have Motorhome exhaust manifolds. The right manifold is the same as the 403 Toro with the crimp in the bend (554581), the LH manifold is Motorhome 455 & 403 only (407103). The intakes were the same as other 403s since it is a small block and is smaller so carb clearance is not an issue. The only way I know of to tell if it is a motorhome engine is the carb & cam. The 403 motorhome uses the same cam as the base 350 (400084) and the toro has a more hp cam (562301). The Mh shows 3 diff carbs for the 403 MH (1977) 17057254, (1978) 17058254, (Calif) 17057559. These #s are on the left side, in front of the boss that runs vertical beside the secondaries.
There are #s on the oil spout, LH front of engine block just under the head, cast #s behind the oil spout, cast #s inside the bell housing but about all you can tell is year model and which plant it was made at at the nickle content of the block. If you got #s I can try to decipher..
| Galen wrote on Wed, 07 November 2012 13:55 |
I've searched the forum and around online, and while I can find references to differences between the auto version of the 403 and the GMC motorhome version, would anyone mind provding a short rundown on the differences, and if there is any way of identifying if an engine is an original motorhome engine? Thanks,
Galen
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] 403 car vs. motorhome engine [message #189507 is a reply to message #189467] |
Wed, 07 November 2012 18:49 |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Galen
The dome or intake manifold is lower on the motorhome engine and the oil
pan is a different shape. There may be a different cam, but that's not
something you can see without dis-assembly...same with the carb.
The exhaust manifolds are different at least one side is ( can't recall
which side right now) and I'm sure someone will pop in with pics of the
differences.
Mike in NS
On Wed, Nov 7, 2012 at 2:55 PM, Galen Briggs <gpbriggs@iowatelecom.net>wrote:
>
>
> I've searched the forum and around online, and while I can find references
> to differences between the auto version of the 403 and the GMC motorhome
> version, would anyone mind provding a short rundown on the differences, and
> if there is any way of identifying if an engine is an original motorhome
> engine? Thanks,
> Galen
> --
> Galen Briggs
> New Virginia, Iowa
> 1978 Palm Beach
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
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| Re: [GMCnet] 403 car vs. motorhome engine [message #189509 is a reply to message #189507] |
Wed, 07 November 2012 18:53 |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
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Galen
If you have more questions, I think you know already who to get your info
from! <VBG>
Thanks Chuck
Mike in NS...still a lot of assembly required,; but coming along....
On Wed, Nov 7, 2012 at 8:49 PM, Kingsley Coach <kingsleygmc@gmail.com>wrote:
> Galen
> The dome or intake manifold is lower on the motorhome engine and the oil
> pan is a different shape. There may be a different cam, but that's not
> something you can see without dis-assembly...same with the carb.
> The exhaust manifolds are different at least one side is ( can't recall
> which side right now) and I'm sure someone will pop in with pics of the
> differences.
>
> Mike in NS
>
>
> On Wed, Nov 7, 2012 at 2:55 PM, Galen Briggs <gpbriggs@iowatelecom.net>wrote:
>
>>
>>
>> I've searched the forum and around online, and while I can find
>> references to differences between the auto version of the 403 and the GMC
>> motorhome version, would anyone mind provding a short rundown on the
>> differences, and if there is any way of identifying if an engine is an
>> original motorhome engine? Thanks,
>> Galen
>> --
>> Galen Briggs
>> New Virginia, Iowa
>> 1978 Palm Beach
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
>
> --
> Michael Beaton
> 1977 Kingsley 26-11
> 1977 Eleganza II 26-3
> Antigonish, NS
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
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| Re: 403 car vs. motorhome engine [message #189522 is a reply to message #189467] |
Wed, 07 November 2012 19:37 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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| Galen wrote on Wed, 07 November 2012 12:55 |
I've searched the forum and around online, and while I can find references to differences between the auto version of the 403 and the GMC motorhome version, would anyone mind provding a short rundown on the differences, and if there is any way of identifying if an engine is an original motorhome engine? Thanks,
Galen
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In addition --/
The oil fill method and the dipstick are unique to the motorhome as well.
So -- someone would have sealed those off but the fill spout elbow might still be in place.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: 403 car vs. motorhome engine [message #189558 is a reply to message #189467] |
Wed, 07 November 2012 21:47 |
Galen
Messages: 146
Registered: November 2011
Location: New Virginia, IA
Karma: 0
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Senior Member |
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Thanks for the good info. I didn't realize the cam was just a stock 350 cam. Good to know. Pretty minor difference really;I guess I expected more than cam and carb.
I had a recent overheat and have pulled my radiator for repair. Got me thinking about my engine. I don't have any history so I don't know if its original, been rebuilt before, or anything. It has the right carb 1705824 for 78, exh manifolds, oil fill, etc... since its in the coach. I'd need to do a little de-greasing (ok alot really) to get any casting numbers.
Thanks again.
Galen
Galen Briggs
New Virginia, Iowa
1978 Palm Beach
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