Topic: Passing Smog?

[rugbypro5]

Hi all,

I'm a novice Firebird owner, about to turn 18, and bought a Trans-Am for my first ride. I'm in Mexico right now, but I'm about to move up to CO and try to get her to pass smog. While I lived up there, I spent a ton of money getting cat. converters, new rods and valves etc., but I still couldn't pass. I have a 403 olds with an Edelbrock 7111 intake and a 1411 carb. Anybody know what I can do?

[Grand73Am]

Move somewhere else, where the car is smog exempt  . But seriously, my guess is that a factory iron intake and a q-jet would have a better chance of passing.

[marx3]

I am certain your problem is the 1411.. a 750 cfm EDELBROCK is propably way too rich for the engine to ever pass. Seriously... on top of this the Edelbrock/ Carter AFB design is not the most sophisticated.
Back in the early seventies GM phased out the Carter AFB because it wasn't sophisticated enough internally to meet the ever tightening emissions demands... This is why GM used the Qjet only.

I may very well be wrong, but my guess is that your 750 cfm Edelbrock is the cause of this. Get a Properly set up Qjet, get the timing set stock and you will be fine.
Where have you set your timing ?

[rugbypro5]

I have no idea, like I said, I'm a novice- novice to cars in general. How do you set up the timing? What does it do? And what is the cfm?

[marx3]

okay, about timing. The timing defines the moment of sparkfire in relation to how far upward in the cylinder the piston has moved.If the spark fires at the correct time in relation to the position of the piston then the most of the energy in the flame is used to push the piston downward: moving the car forward. Since the combustion takes the same amount of time no matter how many rpm the engine is turning, the spark has to fire sooner the more rpm the engine is doing. This is why you have to "set" the timing correct.
You check timing with a timing ligth while the engine is idling. ( or have someone who has the tools and the knowledge do it while you stand by and watch and learn )
There is a decal in the front of the enginebay where you will find various informations on the enginesettings. Timing is one of them.

about cfm: the size of a carburetor is define by how many cubicfeet of air can flow through its barrels per minute.
These cars where born with an 800 cfm Rochester Qjet carburetor. This propably sounds confusing since I have just stated that your current carburetor is too big at 750 cfm.
There are two types of 4-barrel carburetor designs: Squarebore where the 4 barrels are the same size and Spreadbore that has 2 small barrels and two much larger barrels.  If a squarebore carburetor is rated at, say 750 cfm it means that the 2 front barrels ( these are the ones used for most normal driving ) are 375 cfm alone. If a squarebore carburetor, like a Rochester Qjet, is rated at 750 cfm it means that the 2 front barrels are rated at 250 cfm. ( the 800 cfm unit is about 300 cfm ). The smaller the barrels, the better the throttleresponse, mileage etc.

but back to your engine: the 750 cfm Edelbrock is propably metering more fuel through its idlesystem than what is good for the engine. If the timing is also off it can easily make the engine pollute more than is allowed...

[marx3]

4 stroke engine explained. ( yours does not have a fuelinjector, but a carburetor instead )
https://www.youtube.com/watch?v=P3tq3XmKx_Q

timing explained
https://www.youtube.com/watch?v=_KEbXwvTxkg

Carburetors explained
https://www.youtube.com/watch?v=5q1wMY5Mgj4

Enjoy :-)

[rugbypro5]

Wow, awesome guys, thank you so much. Alright, so when I get back in the states, I have a few friends of mine who know cars and might have those tools to test for the timing, I'll ask them if they can help. Again, thank you guys a lot

[marx3]

no problem. We all started out not knowing much :-)

[Bandit818]

Move to CA pay $350 for smog & you don't have to touch anything under the hood