I was driving behind a bel aire the other day, beautiful car. Anyway, the exhaust was horrible. It sounded good, but didn't smell it. I know that a properly tuned car isn't as bad, but I'm thinking about adding converters for emissions. It's strange, ever since owning my corvette, I feel I'm part of a larger group and don't want to make others look badly on corvette owners. Am I nuts?

I've got a 440hp 383 with a pypes stainless exhaust (which may have to be replaced if the one side can't be fixed cheap enough). I'd like to not kill my performance so I'd be looking for high flow components.

 

Before this thread turns into another "is global warming real or not" fights, I'll say this. Your not nuts. and its totally do-able to put cats on a 74. One main thing to look out for is carb jetting, if its on the rich side, you'll melt the cats. and with new style cats, the performance loss with them almost none. EFI is the first class way to go, but hurts the wallet performance.


It basicly boils down to this. This a collective interest, but in the end...and individual hobby. If ya wana clean up your C3, go for it.


Bob
"4 years in uniform fighting for Every American's right to drive a C3"

 

Hell, you might be!

But then I'm there with ya. I've been thinking along the same lines when I swap to fuel injection. There are a couple of issues I'm concerned about with adding cats. One - how much extra heat can I expect to find its way into the cabin. Two - will the cats generate enough heat to catch dry grass on fire if I ever need to park in the grass somewhere. Due diligence is in order to make sure the design and installation is proper.

DC

 

OK, I'll wade into this one. First of all you're intentions are admirable. But I think you may be underestimating what is required to clean up a car's exhaust. Just adding cats will not make an engine clean. From the 1970's to today's modern cars much research and development has gone into cleaning up exhaust emissions. These emissions are measured in the parts per millions. In order to effect reasonable change on emissions control must be maintained over many engine functions not the least of which is the fuel charge. In order to accomplish this all manufacturers have gone to computer controlled fuel injection along with modifications to the engine's operating environment including water temperature, calculations based on manifold absolute pressure, mass air flow, exhaust temperature, computer controlled timing, etc. The idea of all this is to control the combustion process as precisely as possible and then clean up what remains via air injection and catalytic converters. If you think you are going to accomplish this with a carb then you really are nuts. As I said your intentions are admirable but if you really want to accomplish the above you should invest in a computer controlled crate engine and the subsequent tuning involved to effect minimum emissions. Less than that and all your doing is making yourself feel good. Good luck.

 

VETFIXR is absolutely correct. That doesn't mean that you can't minimize emissions on a carbed vehicle. To do so, you need to tune it properly, retard it a bit so it will run a bit hotter [thus, burn off excess hydrocarbons in the combustion process], and make the stock PCV and fuel vent cannister active. The carb needs to be jetted and adjusted for optimum air/fuel ratio [at least, as good as you can do with a carb], also. Good luck.

 

Some very good points here... I definitely think that tuning the carb is the first step. I want to swap my edelbrock 800 for a holley 750 dp. DC3 had a good point with how hot it would be. The best place would be directly below my feet and it's already quite hot enough without two burning cats. So, I think I'm going to get back to tuning the carb and maybe get my timing settled.

BTW, my car is WAY better than most older cars, I'm just trying to minimize it as much as possible. Thanks guys!