I was looking through a JC Whitney catalog, and saw that they had generic catalytic converters in the $70 to $100 range. Since I was going to upgrade the exhaust when I do my Super Six swap in my '65 Valiant (225 /6, auto) anyway, would the addition of this converter be a good idea to reduce emissions? Would I ruin the converter in short order because the engine was not designed for it? Would the back pressure have a detrimental effect on the operation of the engine? And, would it really help the clean the exhaust? It doesn't have to meet any emissions standards here in Va., of course- I just wanted to make it burn cleaner. Has anybody done this? I thought it might be a good idea.

I do not think you would gain anything. first of all the motor was not designed to run a converter and I do not think the converter would last very long in this case.
I think it would probably do more harm than good.
This is just my 2 cents.

The carburetors used on engines with catalytic converter are calibrated a bit different as far as I know. Probably leaner. Also they need to hold tighter fuel ratios for use with catalytic converter.

75-up A-bodies (and other 75-up Chryco cars) with converter have an extra hump in the floor under drivers seat to make room to mount the converter and they have heat shields under the car to keep your carpet from starting on fire.

Adding a catalytic would help reduce your emissions. However, as mentioned above, you would have to take care of clearance issues and work out a heat shield since catalytic converters can get to be over 1000 degrees. A catalytic will work with any carb (I have a catalytic on my 84 van that has an edelbrock performer intake and carb) but won't really be effective unless you work out a means of injecting a flow of oxygen directly into the converter, such as an AIR injection pump or a pulse air injection system.

I say if you have the money and time go for it. There is no doubt that when working properly catalytics drastically reduce emissions. The air isn't getting any cleaner, so we all should help make our cars pollute as little as possible. On my van I have removed all emissions devices except the catalytic and air pump and I pass emmissions with almost no pollutant output.

I got a converter last year for about $40 off ebay. Brand new and any size I wanted. Looks good, but I don't recall the name of the supplier.

Keep your eyes out for inflated shipping charges, but under $50 is damn cheap for a universal converter.

Even a new engine will ruin a converter if it is running poorly or blowing smoke. Make this is the last thing on your list of tune up items, get everything running really good and clean without the converter, and then add it on last if you are still inclined. I won't stop anyone from making the air cleaner, but a converter won't help if the motor is running like cr@p.

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1980 Aspen 225 super six

Won't.

A catalytic converter only oxidizes HC and CO and reduces NOx when the mixture is stoichiometric (14.7 parts air, 1 part fuel).
Fuel and ignition systems (and, later, engine management systems) got a great deal more complex with the introduction of the catalytic converter. The older carburetors and distributors were generally not capable of providing the much more precise, tight control over fuel metering and spark timing necessary to give the catcon something it could work with. The pre-catalyst way of calibrating driveability at the factory, at the engineering stage, was to throw more fuel in to cover up myriad problems (big and little hesitations, big and little surges, etc.). From the driveability standpoint, this works, but fuel economy and emission control go right out the window. Tighter, more precise control of engine operating parameters was what was needed, and that's what happened -- and that's why.

Just throwing a catalyst in the exhaust system will not do anything beneficial at all, and the high levels of HC in a pre-control car's exhaust will likely melt down the core in short order.

Why would you want a catalytic convertor on a 65 anyway. That car is probably exempt from emmisions testing anyway. Like replacing your exhaust with a straw.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

He said:
"It doesn't have to meet any emissions standards here in Va., of course- I just wanted to make it burn cleaner. Has anybody done this? I thought it might be a good idea."

I'd say that the "Catalysts will ruin engine performance for all time and destroy Detroit" argument ended in about 1985. Cars today are better than ever performance wise and much cleaner at the same time. I applaud our friend for looking into making his Slant cleaner.

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"Former Owner" of '65 Barracuda, 225, Auto, MP 2bbl intake, MP cam, Dutra Duals. Presently Moparless.

Thanks for the responses- I was unaware that I would need to pump air into the exhaust stream and install a heat shield. It sound like it is a little more involved than I was expecting. When I was considering it, I was planning on installing a whole new exhaust system anyway for the 2 bbl "Super Six" conversion, and since the exhaust was going to be wider than the 1bbl stock anyway I thought that it would be an opportune time to add a catalytic converter. Now that I see that I can't simply hook it up and have it work, I will scrap the plan- it sounds like without air injection, the converter will be ineffective anyway.

Hang on! The Super Six donor car will have a catalytic, just grab the first few feet of exhaust pipe as well. Use a smog head (with the air injection port behind the #6 exhaust port) and a Canadian slant pulse air injection system and you are set. I plan on doing this to my Dodve van someday (once I yank the 360 and build a 225 to go in its place).

The exhaust pipe configuration on a '63-'66 A-body isn't even remotely close to that on any Super Six car (F & M bodies). It's on the other side of the car, and that's just for openers. And even adding air injection is not enough. Exhaust composition control to a degree far greater than obtainable with a '60s fuel and ignition system is necessary to have a catalyst work. There are also serious fire danger issues throwing a cat on a car not designed for it (carpets can and do catch fire even with garage-engineered "heat shields").

Adding a catcon to a car not originally so equipped isn't as smart or effective an idea as you seem to think it is.

Keep your pre-catalyst car in proper repair and proper tune, and you're doing your part for air quality.

Don't forget youre going to need stellite valve seats for the conversion. (I guess theyd come with the smog head)

This is all moot anyway. Converting the car to catalyst is going to be just as complicated and expensive as converting it to run on propane, and you wont have a manual of conversion guidelines, at that. This is a wasps nest that needs not be disturbed. Besides, by driving that car the way it is, you are polluting at a net lesser amount than if you were to buy a new vehicle and drive it for the same time period (think of all the energy spent and the non recyclable materials created in the birth of a new automobile).

You know what if you want to drive down emissions and save 15 to 20% on fuel costs to boot why don't you just take that car and have it converted to propane. It burns much cleaner, has a higher octane rating and is more economical to operate. You can even hotrod the engine to take advantage of the higher octane rating and have a more powerful engine without all the emissions.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

Ummm.... no, your guess is wrong to the best of my knowledge.

Propane conversion complicated? No. I did my own Slant 6 to propane conversion. All the parts were bolt on and go. Of course you need the technical knowledge of this stuff and then calibrate the fuel ratios afterwards. Here's a picture of my slant 6 truck on propane. Everything is just bolted on. Switch in cab selects either propane or gasoline. The propane system is independent from the gasoline system.

Pre-catalyst engines did not use hardened valve seats because leaded fuels provided a cushion that prevented valve seat recession. With that protection gone, hardened valve seats are required. (ok, maybe not stellites per se, but nickel, stainless, whatever you choose.)

Your conversion looks like a dual fuel spud-in conversion, and it looks properly done, but an LPG exclusive conversion is considerably more involved. A proper LPG conversion requires considerable forethought, as Im sure Frank Raso will tell you, and I happen to be a licenced ICE-IV-P technician myself, so I am aware of laws and codes that need to be followed. Also, certain engine modifications (spark recurving, increasing compression ratio, isolating manifold heat etc.,) can dramatically increase power and fuel mileage. And unless you are buying all your parts used and doing the install yourself, a proper conversion will price in the four figure range. You will still need to have it certified, and re-inspected according to locally mandated intervals or you wont be able to get it refueled.

I would easily rate a catalyst conversion in terms of price and degree of complication among an LPG conversion.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.