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Re: [GMCnet] California smogged coaches [message #271137 is a reply to message #271131] Tue, 03 February 2015 19:49 Go to previous messageGo to previous message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma:
Senior Member
Gee, I was only repeating what I was taught at GM Training School at Tigard
Oregon when I attended. They could have been wrong. Sure hate to think
after all these years that GM could have gotten it so wrong.
Jim Hupy
Salem, OR
78 GMC Royale 403

On Tue, Feb 3, 2015 at 5:21 PM, Richard Michelhaugh <
rick.michelhaugh@frontiernet.net> wrote:

> Minor correction on the EGR function.
> The EGR introduces exhaust gases into the fuel/air stream to reduce the
> peak combustion temperature thus lowering the NOx production. It lowers the
> peak combustion temp by using the inert exhaust gases as a heat sink and
> reducing the amount of fuel/air sucked into the cylinder.
> Not the same phenomena as using a higher octane fuel.
>
> Rick M.
>
> James Hupy wrote on Mon, 02 February 2015 16:41
>> There is no smog stuff with the possible exception of spark retard or
> lean
>> carb jets that will affect performance. The EGR valve mixes exhaust
> gasses
>> into the incoming fuel air mix and slows down the rate of combustion.
> Kinda
>> like a higher octane fuel might do. If you remove it, the engine will
>> probably have to have the spark advance retarded to keep it from pinging
>> when the engine is fully warmed up. There is no power robbing things
> like a
>> smog pump that is engine driven. The double charcoal canister system on
> the
>> California coaches just recycle gasoline vapors from the fuel tank and
> carb
>> float bowl back into the intake tract. Better to burn them there where it
>> might possibly make a tiny bit more horsepower than to vent them to the
>> atmosphere where we have to breathe them and have them help create smog.
>> Jim Hupy
>> Salem, OR
>> 78 GMC Royale 403
>>
>> On Mon, Feb 2, 2015 at 1:24 PM, Robert Mueller
>> wrote:
>>
>>> Scott,
>>>
>>> I am of the opinion that if you removed all the California emissions
>>> control "stuff" you wouldn't feel any seat of the pants
>>> improvement, you might see it on a dyno.
>>>
>>> Johnny,
>>>
>>> Also there are specific part numbers for California carbs.
>>>
>>> http://gmcmotorhome.info/engine.html#carb
>>>
>>> Regards,
>>> Rob M.
>>> The Pedantic Mechanic
>>> Sydney, Australia
>>> AUS '75 Avion - The Blue Streak TZE365V100428
>>> USA '75 Avion - Double Trouble TZE365V100426
>>>
>>> -----Original Message-----
>>> From: Johnny Bridges
>>>
>>> I >think< about the only difference on my '76, which was a CA coach
>>> originally, a second vapor cannister in series with the first
>>> one, and a thermo switch on the distributor vacuum plus a slightly
>>> different carb - it lists under a different number. I can't tell
>>> any difference in how it drives or the mileage from the 49 ones.
> After
>>> 76, there may be nore difference. Any of the gurus know of
>>> anything else different on a '76?
>>>
>>> --johnny
>>>
>>>
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>
> --
> 1974 26' Canyonlands
> aka "The General"
> Clinton, TN
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