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Emission Controls [message #325016] Mon, 16 October 2017 18:14 Go to next message
Cesar Carrasco is currently offline  Cesar Carrasco   United States
Messages: 30
Registered: September 2017
Location: Riverside, California
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Member
Hello fellow GMCer's, I just recently bought two GMC RV's. One is a 1973 23' Sequoia, the other is a 1974 26' Glacier(both are in the registry). The Sequoia (66k miles) had the motor, trans and final drive rebuilt, it has a holly carb and headers; and what from what I can see it doesn't have the emission control parts. The Glacier (51k miles) appears to be all original. I live in Riverside California and both RV's are exempt from smog checks. I would like to get your thoughts on whether or not to remove the emissions controls. For example the distributor spark retarding vacuum, etc. and any others you may or may not recommend.

What are the pros and cons?

Re: Emission Controls [message #325018 is a reply to message #325016] Mon, 16 October 2017 19:13 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
Cesar Carrasco wrote on Mon, 16 October 2017 19:14
Hello fellow GMCer's, I just recently bought two GMC RV's. One is a 1973 23' Sequoia, the other is a 1974 26' Glacier(both are in the registry). The Sequoia (66k miles) had the motor, trans and final drive rebuilt, it has a holly carb and headers; and what from what I can see it doesn't have the emission control parts. The Glacier (51k miles) appears to be all original. I live in Riverside California and both RV's are exempt from smog checks. I would like to get your thoughts on whether or not to remove the emissions controls. For example the distributor spark retarding vacuum, etc. and any others you may or may not recommend.

What are the pros and cons?

Cesar,

Even in California, a '73 had almost no emission controls.
There are really two that I know of only because my coach lived in California a while and had to be converted to CARB standards to be registered.

One is the double charcoal canister. That caused me untold grief until I removed the added can. You do want the one can as that is where the air goes in to replace the fuel drawn out. If you disassemble the parts it is pretty clear how to take that bottom can out.

The other is the TVS Thermal Vacuum Switch. This sends vacuum from the ported tap on the carburetor to the distributor at idle and changes to a manifold port if the engine gets too hot. This speeds up the engine so it both pumps more coolant and the fan pulls more air. Part of the reason the engine gets too hot at idle is because it is running with the timing too far retarded. If you disconnect the TVS and lead the manifold vacuum to the distributor, you will have to back the idle off at the carburetor to get it to be rational again. I did this and mine runs just fine that way.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] Emission Controls [message #325019 is a reply to message #325016] Mon, 16 October 2017 19:15 Go to previous messageGo to next message
johnd01 is currently offline  johnd01   United States
Messages: 354
Registered: July 2017
Location: Sacrameot
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Senior Member
Are you sure these units do not have an extra 100,000 miles on them.

On Mon, Oct 16, 2017 at 4:14 PM, Cesar Carrasco
wrote:

> Hello fellow GMCer's, I just recently bought two GMC RV's. One is a 1973
> 23' Sequoia, the other is a 1974 26' Glacier(both are in the registry).
> The Sequoia (66k miles) had the motor, trans and final drive rebuilt, it
> has a holly carb and headers; and what from what I can see it doesn't have
> the emission control parts. The Glacier (51k miles) appears to be all
> original. I live in Riverside California and both RV's are exempt from smog
> checks. I would like to get your thoughts on whether or not to remove the
> emissions controls. For example the distributor spark retarding vacuum,
> etc. and any others you may or may not recommend.
>
> What are the pros and cons?
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--

*John Phillips*
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Johnd01 John Phillips Avion A2600 TZE064V101164 Rancho Cordova, CA (Sacramento)
Re: [GMCnet] Emission Controls [message #325020 is a reply to message #325019] Mon, 16 October 2017 19:31 Go to previous messageGo to next message
Cesar Carrasco is currently offline  Cesar Carrasco   United States
Messages: 30
Registered: September 2017
Location: Riverside, California
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Member
Thank you Matt. It's just one more thing to eliminate when I'm trouble shooting the engines. They both run good, but not yet 100%.

John, the 23 footer came with plenty of documentation. The 26 footer came with not much documentation. Both do appear to have sat out in the open air for many years and both odometers appear to work properly. No water leaks or damage.





Sent from my iPhone

> On Oct 16, 2017, at 5:15 PM, John Phillips wrote:
>
> Are you sure these units do not have an extra 100,000 miles on them.
>
> On Mon, Oct 16, 2017 at 4:14 PM, Cesar Carrasco
> wrote:
>
>> Hello fellow GMCer's, I just recently bought two GMC RV's. One is a 1973
>> 23' Sequoia, the other is a 1974 26' Glacier(both are in the registry).
>> The Sequoia (66k miles) had the motor, trans and final drive rebuilt, it
>> has a holly carb and headers; and what from what I can see it doesn't have
>> the emission control parts. The Glacier (51k miles) appears to be all
>> original. I live in Riverside California and both RV's are exempt from smog
>> checks. I would like to get your thoughts on whether or not to remove the
>> emissions controls. For example the distributor spark retarding vacuum,
>> etc. and any others you may or may not recommend.
>>
>> What are the pros and cons?
>>
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
>
> *John Phillips*
> _______________________________________________
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Re: [GMCnet] Emission Controls [message #325027 is a reply to message #325020] Mon, 16 October 2017 23:04 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
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Registered: July 2006
Location: Belmont, CA
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Senior Member
>
> ​My feeling is that more you understand the emission system on our
> coach,more you appreciate what they did.
>
​We get in coaches where po have tried to eliminate the system without
fully understand what each does.​

​The end results are seldom good.​



>
>
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: [GMCnet] Emission Controls [message #325028 is a reply to message #325027] Mon, 16 October 2017 23:10 Go to previous messageGo to next message
Cesar Carrasco is currently offline  Cesar Carrasco   United States
Messages: 30
Registered: September 2017
Location: Riverside, California
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Member
Jim, are there any other publications on the emission system other than the
maintenance manuals?



On Mon, Oct 16, 2017 at 9:04 PM, Jim Kanomata wrote:

>>
>> ​My feeling is that more you understand the emission system on our
>> coach,more you appreciate what they did.
>>
> ​We get in coaches where po have tried to eliminate the system without
> fully understand what each does.​
>
> ​The end results are seldom good.​
>
>
> ​
>>
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Emission Controls [message #325029 is a reply to message #325028] Mon, 16 October 2017 23:54 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
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Registered: July 2006
Location: Belmont, CA
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Senior Member
​I'm sure there is, but they never explain it all as it is written for
people that are in the business and know enough about each.​
I'm in a middle of working on an Air Filter Housing job for Tesla so I will
look them up and we can discuss it then.
Get me your email address.

On Mon, Oct 16, 2017 at 9:10 PM, Cesar Carrasco
wrote:

> Jim, are there any other publications on the emission system other than the
> maintenance manuals?
>
>
>
> On Mon, Oct 16, 2017 at 9:04 PM, Jim Kanomata
> wrote:
>
>>>
>>> ​My feeling is that more you understand the emission system on our
>>> coach,more you appreciate what they did.
>>>
>> ​We get in coaches where po have tried to eliminate the system without
>> fully understand what each does.​
>>
>> ​The end results are seldom good.​
>>
>>
>> ​
>>>
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
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> Unsubscribe or Change List Options:
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>



--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: [GMCnet] Emission Controls [message #325033 is a reply to message #325029] Tue, 17 October 2017 00:43 Go to previous messageGo to next message
Cesar Carrasco is currently offline  Cesar Carrasco   United States
Messages: 30
Registered: September 2017
Location: Riverside, California
Karma: 0
Member
My email address is: ccarrasco2013@gmail.com.

Thanks again Jim.



On Mon, Oct 16, 2017 at 9:54 PM, Jim Kanomata wrote:

> ​I'm sure there is, but they never explain it all as it is written for
> people that are in the business and know enough about each.​
> I'm in a middle of working on an Air Filter Housing job for Tesla so I will
> look them up and we can discuss it then.
> Get me your email address.
>
> On Mon, Oct 16, 2017 at 9:10 PM, Cesar Carrasco
> wrote:
>
>> Jim, are there any other publications on the emission system other than
> the
>> maintenance manuals?
>>
>>
>>
>> On Mon, Oct 16, 2017 at 9:04 PM, Jim Kanomata
>> wrote:
>>
>>>>
>>>> ​My feeling is that more you understand the emission system on our
>>>> coach,more you appreciate what they did.
>>>>
>>> ​We get in coaches where po have tried to eliminate the system without
>>> fully understand what each does.​
>>>
>>> ​The end results are seldom good.​
>>>
>>>
>>> ​
>>>>
>>>>
>>> _______________________________________________
>>> 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
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
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Re: Emission Controls [message #325038 is a reply to message #325016] Tue, 17 October 2017 09:03 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
Learn each system and what they do. There was no A.I.R. or exhaust heat riser on a GMC and it predated. EGR and Cats started fully in 75 but was exempt due to GVW
Non Calif emissions had:
1)Evaporative emissions- a great thing with self regenerating charcoal to catch vapors and reburn. Could only imcrease mileage by minimiziing evap and
Reburning
2) Early fuel evaporation or called AC AutoThermAC carb air preheat. This blended hot and cold air to keep intake air at about 115F. This helped during warmup cycle and minimized fuel pooling and cyl washdown. It kept the air to the Qjet at a more consistent temp so the engineers could tune slightly leaner without drivability issues as fuel vaporized more easily. Under heavy throttle the blend door motor has low vacuum signal so the spring returns it to full cold air so no performance downside. In warm weather it is wide open anyway due to high underhood temps.
3) TVS Thermal Vacuum Switch. Allows ported vac signal to distributor 99% of time. If coolant gets over 220F the switch snaps and sends manifold vac to the dist. This picks up idle speed if in a traffic jam etc and aides cooling. My GMC runs cool at idle in extreme temps simply because there is no road load heat to disipate. This only actvated once or twice when a traffic jam happened immediately after high speed cruise and road load heat did not have time to shed. A great device in this situation. It worked great, then after a few minutes the switch snapped back to ported and idled dropped slightly.

Calif vehicles had a second charcoal canister as well as a complicated throttle kicker setup to control idle speed. They also had specifc Calif carbs and distributors. Someone else will have to chime in on these as mine is Federal and never laid eyes on one.
I see only good reasons to keep 1,2,and 3 above as good running and low emissions usually run hand in hand. If you are misfiring during warmup you are poluting air and your oil. If you are overheating your NOX emmisions may go high.


John Lebetski
Woodstock, IL
77 Eleganza II
Re: Emission Controls [message #325039 is a reply to message #325016] Tue, 17 October 2017 09:09 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
Also if you have to come to a quick stop with a highway traffic jam on a 100deg day, and the TVS picks up the idle, a secondary advantage is your dash air will work better and the higher fan speed will help the High Side pressures from going extreme.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: [GMCnet] Emission Controls [message #325043 is a reply to message #325039] Tue, 17 October 2017 12:23 Go to previous message
Cesar Carrasco is currently offline  Cesar Carrasco   United States
Messages: 30
Registered: September 2017
Location: Riverside, California
Karma: 0
Member
John, thank you for your valuable information, I greatly appreciate it. My main concern was the retarding and advancing of the timing and potential overheating damage if the TVS switch fails.

Cesar



Sent from my iPhone

> On Oct 17, 2017, at 7:09 AM, John R. Lebetski wrote:
>
> Also if you have to come to a quick stop with a highway traffic jam on a 100deg day, and the TVS picks up the idle, a secondary advantage is your dash
> air will work better and the higher fan speed will help the High Side pressures from going extreme.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
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