| Re: Emission Controls [message #325018 is a reply to message #325016] |
Mon, 16 October 2017 19:13   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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Cesar Carrasco wrote on Mon, 16 October 2017 19:14Hello 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
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