Catalytic Converter

[wagoneer]

Has anybody placed a catalytic converter on their Mopar? A two-stage may be sufficiently capable of managing the CO2 from our older engines. From what I read online, it seems a three stage would not be possible because the efficiency of our older engines may not be close enough stoichiometrically speaking to prevent the cat from fouling fairly quickly. 

 

Problems I have seen online include risks of overheating the floor pan, 

 

I'm looking for better (reduced) exhaust smell , possibly the addition of a PCV system. , and  quieter consistent exhaust in conjunction with a proper muffler

 

 

[Sniper]

Here's a somewhat technical paper on retrofitting a cat.  Even the two way units need additional items besides a cat to function.  Location of the cat itself must be close enough to the engine to heat up and work, but not so close as to overheat and melt.  Then there is the radiated heat from the cat you mentioned.  Poorly shielded cats have been known to start grass fires if parked off road and running.

 

http://www.meca.org/galleries/files/gasretrofit.pdf

[Plymouthy Adams]

personally I think a good state of tune would be all that is required here...

[Tom Skinner]

Plymouthy Adams,

Ditto.

Flat Heads are meant to breathe. Run Flat Heads Run. 

 

 

 

[wagoneer]

Great link @Sniper .  @Plymouthy Adams I agree that a tune up is necessary, but I'm looking to make my C38 as street-friendly as possible.

 

I'd like to be able to idle in front of a coffee shop without stinking up the place. The  C38+ have huge displacement power that is literally wasted power most of the time. It seems the Fluid drive equipped mopars are pretty much equiped already to handle a 2-stage catalytic converter. A 3-stage would require brains beyond the time of 1948 (electronics in the form of a fancy Carburetor with Electronic metering) that is a bit more than I'm looking for.. 

 

 

1.   Could potentially put in the Chrysler lean jets or just properly tune the carb per spec

2.  ??

3.  ??

4. easy enough

5. buy correct size

6. built-in for Fluid drive Carter B&B

 

 

The percent reductions in HC, CO, and NOx with a two-stage system alone is pretty dramatic. 

 

 

 

[desoto1939]

another question are you useing a Lead Adative to your gas.  Lead was removed from gasoline when they started to use the cat convertor. so if you use lead then you will ruin the cat convertor.

 

Rich Hartung

[Plymouthy Adams]

if I understand most all things related to the old car is grandfathered...BUT...if we the owner see fit to do upgrades like say seat belts for one, once in place they are now subject to the law of the land and become ticket able offences if not used.  I would also think that any catalytic converter once in place and discovered by a local inspection should your state require physical inspections and such, that you are now in a category that would mandate compliance to all attributes of the current clean air act and or retro if you can prove the dated application of said converter from the era you selected to use.  This could work in your favor but could also bite you in the butt...I would solicit guidance from your local DMV and their guidelines to retrofitting.  Many put later model engine and drivetrains into vehicles then circumvent the devices that should be in place.    Anyway, right or wrong that is how I see it....one day it may boil down to forced compliance but till then...keep it tuned and enjoy the drive.

[greg g]

If it's running rich enough to stink, something's wrong with your fuel delivery system. Incorrect carburetor. Incorrect float setting, stuck step up valve, restricted air supply, late spark delivery, low compression, to low operating temperature, incorrect spark plugs, insufficient point gap, insufficient dwell time, weak coil, inefficient spark put wires, restricted exhaust.  Get those sorted before adding stuff that wasn't originally engineered for the car.

[Plymouthy Adams]

12 minutes ago, greg g said:

If it's running rich enough to stink, something's wrong with your fuel delivery system. Incorrect carburetor. Incorrect float setting, stuck step up valve, restricted air supply, late spark delivery, low compression, to low operating temperature, incorrect spark plugs, insufficient point gap, insufficient dwell time, weak coil, inefficient spark put wires, restricted exhaust.  Get those sorted before adding stuff that wasn't originally engineered for the car.

 

 

in other words....tune that sucker up.....!!!!!!!!!

[greg g]

You say pototo I say potato.  Get it running better.  Then stick a sniffer up its pipe and see what it says.

[Marcel Backs]

Nothing but stock exhaust will get by safety inspection in this province. Check your local compliance standards because it could be much ado about nothing. A well tuned flatty without a cat,  probably puts out less GHG than one of those lousy recalled Vdumb jettas. M

[Plymouthy Adams]

another old saying in the hobby..........it smokes, but it old enough to do so....

[Plymouthy Adams]

8 minutes ago, greg g said:

You say pototo I say potato.  Get it running better.  Then stick a sniffer up its pipe and see what it says.

 

its tater.......!!!!

[greg g]

Day yum!! Yer right!  It's mater too ain't it?

[Plymouthy Adams]

close enough Greg, close enough....

[wagoneer]

1 hour ago, Plymouthy Adams said:

if I understand most all things related to the old car is grandfathered...BUT...if we the owner see fit to do upgrades like say seat belts for one, once in place they are now subject to the law of the land and become ticket able offences if not used.  I would also think that any catalytic converter once in place and discovered by a local inspection should your state require physical inspections and such, that you are now in a category that would mandate compliance to all attributes of the current clean air act and or retro if you can prove the dated application of said converter from the era you selected to use.  This could work in your favor but could also bite you in the butt...I would solicit guidance from your local DMV and their guidelines to retrofitting.  Many put later model engine and drivetrains into vehicles then circumvent the devices that should be in place.    Anyway, right or wrong that is how I see it....one day it may boil down to forced compliance but till then...keep it tuned and enjoy the drive.

 

 

I take all of your points on the tune up - and I am going through those steps separately.

 

My original question stands even as a technical curiosity --

 

   Has anybody put catalytic converter(s) on their flathead 6 successfully?

 

 

I only found this reference from @brian hood on a slant 6, and the result was a fouled convertor. 

 

 

 

----------

 

NC Regulation

 

No such sophisticated dynamic regulation here in North Carolina as far as I can tell. The only factor is age of vehicle. In fact, in NC, the C38 is NOT subject to safety nor emissions inspection ever. Emissions are not required for vehicles older than 20 years. Seatbelts are the same. 

 

https://www.ncdps.gov/our-organization/law-enforcement/state-highway-patrol/faq/seat-belts

https://www.ncdot.gov/news/press-releases/Pages/2019/2019-11-19-twenty-year-rolling-emissions-inspections.aspx

https://www.ncdot.gov/dmv/title-registration/emissions-safety/Pages/safety-inspections.aspx

 

 

Edited April 12, 2021 by wagoneer

[Sniper]

I don't know about NC, but in TX antique plates pretty much limit your driving severely.

 

So I have regular plates and I go thru the safety inspection every year.  I read a site where some guy was going on about how you could beat the antique plate restrictions here in TX.  Why?  The safety inspection is cheap and less aggravating, imo, than trying to talk your way out of a ticket if a cop is eyeballing you.

[Tom Skinner]

Doesn't idling in front of a coffee shop pretty much destroy the environment? What does street friendly mean?

Maybe rebuild a carb, set timing, replace or set washer spacing at the vacumm advance, or set the idle mixture at the carb, etc..

My 1948 Chrysler is quieter than my wife's Toyota Avalon and smells better to boot. Mr. wagoneer buy all the parts you want.

 

 

 

 

[Plymouthy Adams]

I have twin cats on my P15  (not the meow/purring kind) but is no flattie.....!

[Marcel Backs]

This goes the same in Quebec. The Antique Auto plate limits you to roads posted 50mph and less and looks like one you affix to a bicycle. We require only one safety check and once it is registered never again even when ownership is transferred within quebec (???). The ministry of transport here along with the local “gendarmes” reserve the right to pull you over at any time to make sure everything is stock and if not they sock it to ya. Sorta a screwed up system but this place is mostly against the grain as far as laws go. I put a regular plate on my car allowing me to go on the provincial highways which roll at 60. M

 

[Marcel Backs]

In article 3.2.1 follow steps 2, 3, & 4. Hastily disregard all other steps! M

[Tom Skinner]

I run Antique plates in here in NC - just run on the weekends (Hagerty Rule) keep mine garaged (Hagarty Rule).

Mr Wagoneer hasn't said what plates he runs. I have run Antique Cars and Motorcycles since 1973 weekends only - because of safety reasons.

It keeps the crazy commuters from running me down literally - they do drive like their spinal columns are disconnected from their bodies.

Probably pretty much like that anywhere I suspect now. Chasing the almighty dollar (their jobs most likely). Not too much civility behind the wheel anymore.

My car holds 60mph. but I drive the older Country Parkways, not the Interstates. They are dangerous for our old busses.

[Tooljunkie]

No way i would put a cat on my flathead. The choke alone will cause issues,and to run a cat it needs more fuel to burn off the emissions. Without a monitoring system, its pretty much pointless. The crank case vent is something that creates a lot of stink, easily solved with a pcv system installed. Im working on 2 pcv valves as i have a little too much blowby, but it runs so well im just going with it. 

[Marcel Backs]

Any roads posted 50 and under out here look like they were shelled. The very poor road maintenance criteria in Queebec makes driving on the upper series highways much better. ATV are allowed to circulate on a good many minor roads and that is how I mostly get around. The immense trail system here is in better shape than the roads cars run on.

[wagoneer]

58 minutes ago, Tom Skinner said:

I run Antique plates in here in NC - just run on the weekends (Hagerty Rule) keep mine garaged (Hagarty Rule).

Mr Wagoneer hasn't said what plates he runs. I have run Antique Cars and Motorcycles since 1973 weekends only - because of safety reasons.

It keeps the crazy commuters from running me down literally - they do drive like their spinal columns are disconnected from their bodies.

Probably pretty much like that anywhere I suspect now. Chasing the almighty dollar (their jobs most likely). Not too much civility behind the wheel anymore.

My car holds 60mph. but I drive the older Country Parkways, not the Interstates. They are dangerous for our old busses.

 

 

I am running Antique plates myself, but really that is only ornamental in North Carolina. Age of vehicle is the key factor. 

Your insurance comments led me to re-read my policy documents word-for-word (very boring), and I do not have those restrictions in my insurance policy about limiting to weekends.  Regardless, my car is a light use daily driver vehicle, and that is my focus of my questions. Granted, my vehicle has gone through a complete restoration in the last 20 years or so, and is therefore very reliable. 

 

There are some limitations with our vehicles related to gearing (limit highway speeds -- see other differential thread), emissions (this thread), and some safety features (seat belts nominally).

 

 

@Tooljunkie I certainly think PCV valve is in my future. I've been studying the PCV diagrams , and eyeing the kits on VPW. 

 

Still, we seem to be underestimating the power we have in our vehicles. 4.1 liter (251 CU) for vehicles that mostly go 60 mph or marginally more. That's a lot of engine and bigger than 2/3 all engines out there. 

 

I'm sensing tension/aversion to applying nominal emissions control mechanisms like PCV, Catalytic converters, but I don't see why? 

 

Still seems that nobody has applied catalytic converters to the inline 6 / 8 Mopar flathead. Putting it in my backlog of work to do, and fun things to try. I think I'll try it on my truck that I am building first. 

 

Look for a future update one day