C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
Sponsored by:
Sponsored by:

74 Big Block Smog Question

Thread Tools
 
Search this Thread
 
Old Mar 14, 2008 | 01:22 PM
  #1  
ROBRICCI's Avatar
ROBRICCI
Thread Starter
Racer
10 Year Member
 
Joined: Feb 2007
Posts: 273
Likes: 0
From: NAPLES FLORIDA
Default 74 Big Block Smog Question

ok...heres one for the experts...

i recently purchased a completely restored smog setup for my 1974 LS4 convertible...as i understand it...everything is correct for my car...except the actual smog housing as it has a automatic transmission part number - instead the correct part number for a 4 speed....

was all i could find close at the time...

regardless..everything else is correct and it is a truly beautiful unit - except - and will really look great on my retored car except -

i think i dont need it...

from what i understand...my engine pad is stamped "CWM" which is correct for a 4 speed ls4...but if it were a smog car...it would be stamped (i think) CMT?

anyway...hopefully somebody knows...cause if i dont need it...and i hope i dont....its for sale -

and it is the nicest restored unit i have ever seen....also..it has all the correct hoses and clamps and brackets...

RR
Reply
Old Mar 14, 2008 | 09:29 PM
  #2  
trw's Avatar
trw
Melting Slicks
20 Year Member
 
Joined: May 2000
Posts: 2,125
Likes: 9
From: Crescent City, CA
Default

All 73-74 454's had a smog pump.
The CMT is a California smog equipped car (sold new in California).
Even back then Cali had tougher smog laws than the Feds.
Terry
Reply
Old Mar 14, 2008 | 10:06 PM
  #3  
ROBRICCI's Avatar
ROBRICCI
Thread Starter
Racer
10 Year Member
 
Joined: Feb 2007
Posts: 273
Likes: 0
From: NAPLES FLORIDA
Default

so what is the difference between a california smog car CWT (454 4- speed) and a non-california smog car CWM (454 4-speed) car?

i mean...if they all came with smog...then why the cali designation?
Reply
Old Mar 15, 2008 | 06:00 AM
  #4  
hunt4cleanair's Avatar
hunt4cleanair
Le Mans Master
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Sep 2002
Posts: 5,234
Likes: 898
From: Myrtle Beach SC
Default

so what is the difference between a california smog car CWT (454 4- speed) and a non-california smog car CWM (454 4-speed) car?

i mean...if they all came with smog...then why the cali designation?
Stricter emission requirements in CA than in other states which meant leaner mixtures and I suspect a different carb number. The pump permitted motors to run greater fuel ratios but still meet emission requirements. I show a part number 7044505 for a 454 with CWT. What is the number on your carb?

As model years rolled by, the emission requirements got stricter and four-speed motors had a harder time meeting the requirements until in 82...there were no four-speeds produced.

Both the auto and four-speed used the same emission certification ZJ (code) which is another indicator of power team configuration.
Reply
Old Mar 15, 2008 | 10:23 AM
  #5  
ROBRICCI's Avatar
ROBRICCI
Thread Starter
Racer
10 Year Member
 
Joined: Feb 2007
Posts: 273
Likes: 0
From: NAPLES FLORIDA
Default

my carb is 7044221 - is this correct for a non california smog 4 speed car CWM?

thanks!

RR
Reply
Old Mar 15, 2008 | 10:52 AM
  #6  
trw's Avatar
trw
Melting Slicks
20 Year Member
 
Joined: May 2000
Posts: 2,125
Likes: 9
From: Crescent City, CA
Default

Originally Posted by ROBRICCI
my carb is 7044221 - is this correct for a non california smog 4 speed car CWM?

thanks!

RR
That is a good number for your car.
Also the distributor was different for Cali cars. I'm sure it was to lean it down.
Reply

Get notified of new replies

To 74 Big Block Smog Question





All times are GMT -4. The time now is 10:00 PM.

story-0
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE
story-1
10 Revolutionary 'Corvette Firsts' Most People Don't Know

Slideshow: 10 Important Corvette 'firsts' that every fan should know.

By Joe Kucinski | 2026-04-29 17:02:16


VIEW MORE
story-2
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-3
2027 Corvette vs The World: Every C8 vs Its Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-24 16:12:42


VIEW MORE
story-4
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE
story-5
5 MOST and 5 LEAST Popular Corvette Model Years in History!

Slideshow: 5 most and least popular Corvette model years.

By Joe Kucinski | 2026-04-08 13:25:01


VIEW MORE
story-6
2027 Corvette Buyer's Guide: Everything You Need to Know!

Slideshow: 2027 Corvette buyer's guide

By Joe Kucinski | 2026-04-17 16:41:08


VIEW MORE
story-7
10 Things C8 Corvette Owners Hate (But Won't Tell You)

Slideshow: 10 things C8 Corvette owners hate, but won't tell you.

By Joe Kucinski | 2026-04-01 18:36:07


VIEW MORE
story-8
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!

Slideshow: Should you add one of these incredible Corvettes to your garage?

By Brett Foote | 2026-04-01 18:14:05


VIEW MORE
story-9
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)

Slideshow: Every Corvette Grand Sport explained

By Joe Kucinski | 2026-03-26 07:13:44


VIEW MORE