marshal135

Hello Forum and Happy New Year.
I pose a ? regarding thee smog holes in big block exhaust manifolds.
I see Big Block exhaust manifolds offered with and without.
At what point were they without?
My 68 BB car came with all the smog stuff removed.
The current manifolds have the air tube holes plugged.
I looked on the forum for an answer and the Chevelle site.
I couldn't find a year cut off per say for without vs with.
I see 38880827/828 manifolds in both configurations.
Thanks,
Marshal

mikem350

You will have to do more research as it varies on the year, which horsepower, and where the car was originally shipped to. Like the infamous CA emissions option.

Griff2002

From another thread.

This C2/C3/C4 listing should help.

A.I.R. PUMP USEAGE (C2, C3, & C4)

Here is a listing that was posted on the NCRS Forum by Joe Lucia....

1966 CA-delivered Corvettes, except for the L-72, used the A.I.R. (RPO K-19) system

1967 CA-delivered Corvettes, used the A.I.R. (RPO K-19) system.

1968 & 1969, ALL Corvettes used the A.I.R. system regardless of engine, transmission, or where delivered.

1970, Chevrolet went to the CCS (Controlled Combustion System) for emissions control on most Corvettes, except the LT-1s.

1971, Corvettes continued to use CCS (except LT-1s and LS-6s).

1972, A.I.R. system returned for most Corvettes except engines except L48s with the "CKW" and "CKX" code.

1973 - 1975, all Corvettes used A.I.R, except for the 1974 L48 with automatic and Federal emissions which used CCS.

1976, all Corvettes returned to CCS, except California-certified cars which used A.I.R.

1977, all Corvettes used CCS, except California and "High Altitude" delivered cars which used A.I.R.

1978 & 1979 all Corvettes used CCS, except California cars, "high altitude" and all L-82s which used A.I.R. L-82s were not available in California or "high altitude" areas during these years.

1980 - 1987, all Corvettes used A.I.R.

1988 - on, A.I.R. was used on most, if not all Corvettes, although many C4s use an electric air pump.

Jim Shea is offline Report Post

Shark Racer

Any idea what C.C.S. entails? Or does it just mean "everything except the stuff California asks for?"

IE EGR/flappers on air cleaner/EFE/PCV/EVAP is on pretty much every car in the late 70's, and then A.I.R. on top for the ones you mentioned.

marshal135

Griff2002,
Thanks for the detailed explanation.
That really helped me understand why the variations.
Thanks,
Marshal

Gale Banks 80'

I don't think it is as Black and White as the list above. The above should be true for most any Car sold at a Dealership. However there were Cars that went straight to Race Teams etc. What about replacement Manifolds sold across the parts counter ? I'd be willing to bet that there are Date Coded Manifolds that fall in the 67-71 range that do not have the holes out there. And if there are, what happens when the car is judged with the right date codes and no holes ?