No AIR on 1974 L-48 TH400 (non-California)

[Duke W.]

Re: No AIR on 1974 L-48 TH400 (non-California)

It can be difficult to get 30+ year old cars through emissions tests since most of the guys doing the testing are younger than the cars.

California inspection stations are supposed to have books that describe the configuration of every engine/drivetrain combination, including pictures, so ask them to look if they question your car. I had that problem in the past with my Cosworth Vega, but now that it has a historical vehicle license plate, it is out of the emission test data base.

Also, as previously stated, the "emission label" on the hood underside or somewhere in the engine compartment has codes for all the emission control devices.

Beyond that, bring the your CSM.

Most states have exemptions for cars beyond a certain age or special emission test-exempt plates like California's HV plate, which is eligible for use on "collector cars" 25 model years old or older.

Check your state to see if there is something comparable. It's makes little sense to emisson test collector cars that are driven a few hundred to a few thousand miles per year, and most states offer some kine of out.

Duke

[Glenn D.]

Re: No AIR on 1974 L-48 TH400 (non-California)

Thank you. The level of knowledge here is unbelievable. That is why I love the TDB. Thanks

[Paul L.]

Re: No AIR on 1974 L-48 TH400 (non-California)

Paul,
Thanks for that tip. I do not have that manual but will get one shortly.

Duke,
Emissions testing (Provincial) only goes back 20 years I believe so the 1974 is exempt. But charges can (and have been) laid under provisions of the Federal Environmental Protection Act (EPA). Basically this means that all emissions equipment on the car when it left the factory (or suitable service replacements) must be on the car today. It is not a sniff test but a visual. The penalties are substantial.

My 1974 has new PCV, EGR, heat riser, etc. but no AIR pump. Hence I carry certification that a 1974 L-48 with automatic transmission was an anomaly amongst the emissions requirements for pre-cat-con C3s.

[Paul L.]

Re: No AIR on 1974 L-48 TH400 (non-California)

I received the 1974 GM Service Manual from EBay. A bargain for $12.00. See 104-54; it confirms that a 1974 L-48 with TH400 did not have an AIR system. But it did have something called CCS. What is that? The PCV?

[Martin N.]

Re: No AIR on 1974 L-48 TH400 (non-California)

[quote=Paul Latour (38817);483384]I received the 1974 GM Service Manual from EBay. A bargain for $12.00. See 104-54; it confirms that a 1974 L-48 with TH400 did not have an AIR system. But it did have something called CCS. What is that? The PCV?


PAUL-
I believe the C.C.S. stands for; "Controlled Combustion System". I'll have to do alittle research but maybe someone out there will recall right away.

Marty

[Joe L.]

Re: No AIR on 1974 L-48 TH400 (non-California)

I received the 1974 GM Service Manual from EBay. A bargain for $12.00. See 104-54; it confirms that a 1974 L-48 with TH400 did not have an AIR system. But it did have something called CCS. What is that? The PCV?

Paul-------

"CCS" is the abbreviation for "Controlled Combustion System". This was an exhaust emissions control system that I believe was first used by Chevrolet for the 1968 model year for many applications with automatic transmissions, but not for 1968 (or 1969) Corvettes.

It was first used on Corvettes for the 1970 model year for all engine applications except LT-1. 1971 was the same except also excluded was LS-6.

Controlled Combustion System used a combination of carburetor and distributor "calibrations" to achieve the required level of exhaust emissions control for the particular year model. Obviously, it was a lot less expensive system than air injection reactor. The downside is that it often creates driveability and performance problems.

[Martin N.]

Re: No AIR on 1974 L-48 TH400 (non-California)

PAUL-

Maybe this will help? I've got more if ya need it.

Marty

[Paul L.]

Re: No AIR on 1974 L-48 TH400 (non-California)

Paul-------

"CCS" is the abbreviation for "Controlled Combustion System". This was an exhaust emissions control system that I believe was first used by Chevrolet for the 1968 model year for many applications with automatic transmissions, but not for 1968 (or 1969) Corvettes.

It was first used on Corvettes for the 1970 model year for all engine applications except LT-1. 1971 was the same except also excluded was LS-6.

Controlled Combustion System used a combination of carburetor and distributor "calibrations" to achieve the required level of exhaust emissions control for the particular year model. Obviously, it was a lot less expensive system than air injection reactor. The downside is that it often creates driveability and performance problems.

Yes, Joe. Probably ported vacuum and retarded timing to 4* BTDC with no vacuum advance at idle. I am using manifold vacuum and 12*BTDC (36* at 2500 with a B26 can) with no pinging. I'll stick with it.