Engine and Driveline
Engine/Transmission/Rear End Housing Overhaul - Air Cleaner Assemblies
A variety of air cleaner assemblies were used from 1970 through 1972. The 1970 model year would be the last year for the open element air cleaner used on the SS396 and SS454 engines without the ZL2 Special Ducted Air System (commonly called 'Cowl Induction' hood). The 307 cubic inch displacement engine, both 350 cubic inch displacement engines, and the LS3 402 used the A348C air filter and closed air cleaner assemblies with a single snorkel for air intake. Some SS454 engines were equipped with a dual snorkel air cleaner in both 1970 and 1971. The 307 cubic inch displacement engine, both 350 cubic inch displacement engines, and the LS3 402 used the A348C air filter and closed air cleaner assemblies with a single snorkel for air intake.
Open element air cleaner assembly found with 402 and 454 Chevelles
not equipped with the ZL2 Special Ducted Air System hood option.
Seen on 1970 LS6 Chevelles between at least January 26 (depending
on the assembly plant) without the ZL2 Special Ducted Air System hood
option is the dual snorkel air cleaner assembly. There is nothing
'rare' or 'special' about this air cleaner assembly.
A number of air cleaner assemblies were used in 1970 depending on the assembly plant and the engine. The air cleaner broadcast code can be found in box #55 on the plant's build sheet.
Arlington, TX.
| Engine | Broadcast Code | Used |
| 454 (LS6) w/o ZL2 | CO | From around sequence #211578(1) |
| 402/454 w/ZL2 | DG | All |
| 402/454 open element | SS | All |
Atlanta, GA.
| Engine | Broadcast Code | Used |
| 454 (LS6) w/o ZL2 | CO | From around sequence #160836(1) |
| 402 (L78) open element | CP | All |
| 402/454 w/ZL2 | DG | All |
| 402/454 open element | SS | All |
Baltimore, MD.
| Engine | Broadcast Code | Used |
| 454 (LS5) | CN | Monte Carlo SS |
| 454 (LS6) w/o ZL2 | CO | From around sequence #139640(1) |
| 454 (LS6) open element | CP | One - sequence #137956 |
| 402/454 w/ZL2 | DG | All |
| 402/454 open element | SS | All |
Kansas City, MO.
| Engine | Broadcast Code | Used |
| 454 (LS6) w/o ZL2 | CO | From around sequence #194351(1) |
| 454 (LS6) open element | CP | One - sequence #193178 |
| 402/454 w/ZL2 | DG | All |
| 402/454 open element | SS | All |
Van Nuys, CA. (Los Angeles)
| Engine | Broadcast Code | Used |
| 454 (LS5) | CN | Monte Carlo SS |
| 454 (LS6) w/o ZL2 | CO | From around sequence #186536(1) |
| 454 (LS6) open element | CP | One - sequence #193178 |
| 402/454 w/ZL2 | DG | All |
| 402/454 open element | SS | All |
(1) The earliest sequence number found to date.
Rumor has it the dual snorkel air cleaner assembly found on the LS6 engines without the ZL2 option is they were to replace the open element air cleaner assembly due to the 'noise' created by the engine at wide open throttle. Whether this is true or not - but it makes for interesting conversation.
When it does get close to engine installation time in the restoration process and you’ve selected a machine shop to do any work needed to the cylinder block and/or cylinder heads, you can begin the engine tear-down procedure. Depending on what ancillary pieces you’ve pulled from the engine to remove it will naturally depend on how much work will be required to tear the engine down. As usual, bag and tag all the small parts like bolts and note where they came from. It is not hard to confuse items such as exhaust manifold bolts with intake manifold bolts come reassembly time. Be sure to bag and note any small clips and photograph their location on the engine block. Also take note and photograph various markings on the bolts head.
Miscellaneous Clips
There are numerous clips under the hood to help route hoses and wiring
away from damage. Many bolts have original equipment manufacturer (OEM)
markings on the head. I can’t stress enough to photograph and document
the location of these various clips and which bolts came from where.
Not only will this information be a valuable resource when reassembling
the engine, transmission, and other assemblies but many are just not
available in the aftermarket world and knowing exactly what you are
looking for will help in your search should get lost or you just can’t
remember where it came from.
These clips are used on the rear of the dual snorkel air cleaner
assembly to support the PCV valve hose and are often very difficult
to find. Be sure to bag and tag them during disassembly.
The same holds true for items like water pump bolts, starter bolts, pulley bolts and especially any washers and special clips used.
Electrical harness support clip found on a 1970 LS6 Chevelle. Details
like this are very important on a Concours restoration and not readily
available in the aftermarket so be careful during disassembly to photograph
its location and bag it.
Pay particular attention to vacuum hose markings and the routing of the hoses as well as wiring connections, especially if your Chevelle is equipped with RPO ZL2 Special Ducted Hood system and the transmission controlled spark (TCS) solenoid.
If your carburetor and/or distributor needs refreshed or a complete overhaul, now would be the time to consider having it done. While it might only need a cleaning and gasket kit that can be done in an evening, if your carburetor needs repair parts or missing parts, a carburetor specialist may be needed and they may require some lead time to fit your job into their schedule.
If you feel confident enough to assemble the engine yourself and install the crankshaft, pistons/rings, camshaft, etc. set your engine block on an engine stand and get started. As an alternative if you are not that confident in the basic engine assembly process, you can ask your machine shop if they can assemble the valves and springs in the cylinder heads and install the rotating assembly of the engine block so all you need to do is bolt the larger pieces together.
You should always try to reuse as much original equipment from the engine as possible before going to aftermarket or even new-old stock (NOS) or original equipment manufacturer (OEM) parts. Even Chevrolet NOS parts are often service replacement items and may not have the correct markings needed for a Concours, judge-ready, restoration.
