Thx for the only decent replies 67 and Colorado.What a phawking crazy idea; trade a few horses for a cleaner running car. Soit isn't practical formy 65 and cats alone won't do much.That's what I was after.

 

I live close to Coeur d'Alene, pretty sweet area. Constantly being named one of the top 10 place to; live, raise a family, retire, vacation, ect. Did it occur to you Idahomight havemore than one town? btw I lived in Denver. Nothing to write home about.

 

Let me play 'Devil's Advocate' for a moment . . .

It's not always easy to run an older car through a periodic emissions test, assuming that you keep 'normal' plates rather than 'Classic', 'Historic', or some such that might buy you a waiver or exemption. So there might be room for argument that easing that sort of difficulty would be worth it in some cases.

The concept of adding converters to a classic is not in itself a technically bad idea. You'd be entirely free to choose from much more free-flowing designs than the pellet type converters that gave the devices such a bad name back in the 70's and early 80's. But the associated details of getting it/them to physically fit whereneeded and work reliably without the risk of being killed off on a regular basis does make it a less than attractive mod (probablydeal-breaker-level unattractive to all but some few withan oddball combination of die-hard environmental allegiances and classic car interest).

On the other hand, with a restomod build employing EFI and closed loop control, you can get a very good balance of power and emissions performance with relatively little worry.

Either way, some of the losses due to increased backpressure could be recovered via less restrictive mufflers than you might be able (or willing) to tolerate all by themselves.


Norm

 

There is a quirk in California emissions laws that requires, although I'm not sure of all the ramifications, the newer year date of the car or engine dictates smog requirements. That means that if you have a 65 Mustang and upgrade to a 2007 4.6L engine, you are required to now pass 2007 smog laws. Now that's not the reality of what is the law, but is a sample of what it could have been. Smog testing does not apply to cars over 30 years old in California. The reality is if you have a 1980 Mustang and upgrade to a 2007 4.6L engine, the law does apply with all the trimmings, converter, sensors, etc. They trap you at the testing stationso there is no (legal) way out. Another 'quirk' allow the 'ricers' to buy a new rice rocket car, make payments, modify it, add parts, take away parts, race (and whatever else they do with them), not worry for four years and then sell or junk it. The first smog test on a new car in California is when the car is four years old.
Jim

 

Jim,

While CA did briefly have a floating 30-year smog test exemption policy, it was not renewed. I believe the cutoff is '75 and older are exempt and '76 and newer still need the checks. BTW, are they running the smog check checkpoints up there like they are in SoCal? They are similar to sobriety checkpoints usually seen at on-ramps. [:@]

You are correct on swapping newer motors. Obviously, on an older smog test exempt vehicle it is moot, but changing motors on new cars can be difficult. The engine must be newer than the vehicle, all its emissions equipment must be installed and I believe the vehicle must have a minimum number of miles before it is eligible for the swap. After everything is together you have to take it to the smog police for inspection. If you pass all the visual and physical inspections, you'll get assigned an exemption sticker which is affixed to the firewall. I've had a few friends swap V8s into Jeeps and it was no picnic.

 

Or run no mufflers at all, in me experience, cat's alone will reduce the DB level to a bearable level. I tried that on a recent build of my son's C-1500 truck, it was reasonably quiet. I was trying to run the stock fuel injection with a Hilley throttle body upgrade, but alas, the throttle body flooded the engine so bad that upon one startup, (finally), the entire exhaust turned a bright shade of red destroying the cat. We took the cat off, shook it a little, and it sounded like a giant baby rattle.

Now the truck is carbed, HEI, no cat..... the computer is still in the truck but,,, it is unemployed....

 

Don't sweat it Smothers, your goal is admirable, but the execution is difficult. I gave the "clean car" effort a shot on my son's truck, it just didn't work out... Flooded engine + Cat = red hot exhaust.... = melted converter. I did this with fuel injection, a carb would give even more oppertunity to "run rich"...

Also consider that the early (carbed) cars with cats, were trading one type of polutants for another,,, When a car with cats runs rich, the cats produce large amounts of sulforous acid in exchange for reduced hydrocarbon emissions, so much that I have heard stories that police officers on traffic detail were actually killed while sitting in one spot for extended periods.

You know the smell, rotten eggs, that you will occasionally smell coming out of the exhaust of a very new car.

Did you ever hear about "acid rain" prior to the advent of catyletic converters?? Coincidence??

I think the newer computer controlled cars hav virturally eliminated this issue, but that just brings us back to where we started...

 

We already have enough people trying to save the spotted owls up here Glen.My friend keptsaying "Hybrid" everytime he saw a Prius this weekend whenever we would go cruising, and let me tell you, I never realized beforehow many hybrids there really are[:@].

 

Jeff,
I think the rolling 30 year is still in effect, however it don't affect me, so I don't know. There are no smog check points that I know of but I don't commute - retirement has some benefits. There were some type of freeway on-ramp photo spots but they dissapeared. Drive by shootings - I hope?
Jim

 

On the pro side: The Cats will measurably reduce the HC and CO emmissions from your tailpipe(s). There are some pretty good hi-perf Cats on the market also.

On the Con side: They're going to run hot and probably burn themselves out sooner due to the lack of up stream controls (air injection, closed loop ignition, etc...). Also of concern is the placement to your floor pan and again the heat they will put off.

I don't think you;ll see much difference in performance if you use the hi-po parts.