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Old 02-08-2005, 09:53 PM   #8
KIILew
Active Member
 
Join Date: Mar 2002
Location: Prosser, WA 99350
Posts: 147
Quote:
Originally Posted by EricS76
This from www.73-87.com


For 1978, all C10/15's with GVW's under 6,000 lbs have converters regardless of engine. All other '78 models (i.e. Big 10's/Heavy Halfs, K10's, C/K 20/25/30/35's)had GVW's over 6,000 lbs, and therefore did not use converters. EXCEPTION: For 1978, all California models with GVW's under 8,500 lbs had cats. Therefore, this California exception included ALL and ONLY 10/15/20/25 series vehicles, including Big 10's/Heavy Halfs.

For 1979, Federal laws, like California statutes in '78, raised the GVW threshold. So, all 1979 models, except for C/K 30/35 vehicles, had cats, nationwide.

For 1980 through 1986, the same models as those for '79 used cats. However, a new C6P heavy duty option was offered for C/K 20/25 models which provided an 8,600 lb suspension package. These new, heavier 3/4 tons cleared the 8,500 lb limit, and so did not use converters during this time period, nor did C/K 30/35's.

Dano69c10:

Your '79 C30 dually pickup has a 10,000 lb GVW (or possibly a 9,000 lb GVW if it is a chassis cab model), and, consistent with the quote above (which I originally authored), was rated as a heavy duty emission class vehicle in California and in the other 49 states as well. Regardless of whether it has an LS9 350 or an LF8 454, your rig should have originally had the following emission controls (which for '79, are shared by the 49 state and California heavy duty emissioned models):

PCV-Positive Crankcase Ventilation
ECS-Evaporation Control System (i.e. your charcoal canisters)
EFE-Early Fuel Evaporation (i.e. that valve in the R.H. exhaust manifold)
TRC-Throttle Return Control
CHA-Carburator Heated Air (i.e. the heat stove to your air cleaner)
AIR-Air Injection Reactor (air pump)
TVSS-Trapped Vacuum Spark System (i.e. assorted vac. tubes/switches)

This listing is also applicable to '79 K30's with the LF4 400 engine.

I noticed that you implied that you have EGR on your engine. That surprised me, because EGR was used on California heavy duty emissioned 454's prior to the '79 model year, but was not cataloged for any heavy duty emissioned V8's used in '79 to early-'85 model year pickups. It reappeared on the heavy duty emissioned 350 and 454 engines (both 49 state and California) just after the start of the '85 model year.

Translation to the above: I would not expect to find EGR originally equipped on your '79 C30. The above listing originally was compiled using original GM data books, but emission schematics for your engine as found in Chiltons, etc. also support the exclusion of EGR from your '79 California heavy duty emissioned 350/400/454. Of course, GM can do whatever they want, regardless of what they print, and I have personally seen some variation particularly with respect to air pump and EFE application. But I would question the necessity- -and originality- -of EGR on your rig.

Regardless, I am confident your vehicle did NOT come equipped originally with a catalytic converter.

Ken Lewis

Later edit: p.s. sorry about the 350 and 400 references; I just noticed in my second reading that your signature confirms that your rig has a 454. The info applies to all three engines, however.

Last edited by KIILew; 02-08-2005 at 10:11 PM.
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