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1976 EGR and smog on a feather duster
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Author:  Aluminum Six [ Tue Aug 28, 2012 4:30 pm ]
Post subject:  1976 EGR and smog on a feather duster
Guys

I'm building a lighter feather duster than stock. I'm just gonna use a 74 body, but what did Chrysler do to the 225 to get it up to 30+ mpg? Someone mentioned they used some tricks with the EGR and maybe timing curve?

Do I need to find a 76 duster's distributor & carb and
wiring harness?

I'm ripping out the backseat and sourcing carbon fiber hood & trunk and since it'll be pre 76 there won't need any aluminum crash bumper stuff because it'll simply not be there.

Please advise.

Thanks
Author:  DusterIdiot [ Tue Aug 28, 2012 6:35 pm ]
Post subject:  Ok...
Quote:
I'm building a lighter feather duster than stock. I'm just gonna use a 74 body, but what did Chrysler do to the 225 to get it up to 30+ mpg? Someone mentioned they used some tricks with the EGR and maybe timing curve?

Do I need to find a 76 duster's distributor & carb and
wiring harness?

I'm ripping out the backseat and sourcing carbon fiber hood & trunk and since it'll be pre 76 there won't need any aluminum crash bumper stuff because it'll simply not be there.
The better years to build the lighter Duster would be 1970-1972...a feather duster in street trim with no drive weighs about as much as a stock 1972 in street trim,

If building the lighter duster out of a 1974-1976 you will need to replace both bumpers and brackets, both the hood and deck lid...to shave more weight you will want to gut the crash protection out of both doors (the 1970-1972 do not have this...you could swap the doors, but then you have window seal changes that may need to happen). I also if I had the budget would swap the metal fenders for fiberglass ones...

The 1976 wiring harness is a 1 year only (like 1975) and has nothing to do with mileage making....everything plugs into the same stuff no matter what slant is under the hood, they just moved around some of the wiring on the fire wall plugs and added a small 4 prong extra in 1975, then in 1976 moved the wiper wiring to the upper spare plug, and the transmission harness to the new lower 4 prong plug.

Once you tackle the weight savings, you will need to figure out your drive train...you'll need to retrofit in an A-833OD manual tranny and set the rear up with a 2.94 gear ratio to match the stock option.

Next we should look at the engine:

Stock late forged crank 225...(1974 would be fine), stock cam, match stock compression (8.2-8.4:1SCR)

Change exhaust pipe to a 2 1/4" header pipe, you will probably omit the cat convertor under the driver's floor pan, 2 1/4" back to the V-8 style muffler then 2" out to the bumper.

You will need a 1976 Dart Lite/Feather Duster Distributor for a manual transmission...(good luck on that).


Do a search for the curve specs, you may be able to replicate it with a late 9R distributor (1977+), and the proper vacc can from SMP.

The one barrel is tailored for driving in the low rpm band due to the heavy car with highway gears and an OD ratio for all highway use, and
is specific to this car only as well.

You will also need to setup the old vaccuum system with radiator and head temperature driven vacc switches to activate the EGR when the car is warm. You will also need the unique EGR to the system, along with the die cast one peice one barrel manifold (for the weight savings).

-D.Idiot
Author:  Reed [ Tue Aug 28, 2012 6:42 pm ]
Post subject: 
I like super mileage builds. You may want to also consider going with a post 81 slant for weight savings. Both the block and crank were considerably lighter than the early 70s era slants.
Author:  DusterIdiot [ Tue Aug 28, 2012 8:28 pm ]
Post subject:  But...
Quote:
Both the block and crank were considerably lighter than the early 70s era slants.
Yes, but you give it back when you need a heavy flywheel to get the fat 70's car moving...

:wink:

-D.Idiot
Author:  Reed [ Tue Aug 28, 2012 10:18 pm ]
Post subject: 
True, true. 8)
Author:  Aluminum Six [ Wed Aug 29, 2012 5:29 am ]
Post subject: 
Thank you D.idiot, that was very helpful. I have a 1962 aluminum block 225 I'm backing up with an aluminum case a833 from a pickup, although some suggest with the longer iron tailshaft that I swap the gears, dogs, and selectors into the shorter shafted 833 for better ratios.

A special dizzy for a 76 manual tranny? Seriously? If its all just weights & springs and a vacuum advance why not just install MSD for a complete burn, which is what I'm assuming they were doing mechanically.

Napa should have access to the EGR? And I have an aluminum electroweld 1bbl (2 actually) and lots of unspoiled junkyard paradises up in northern Wisconsin and Michigan's upper penninaula.
Author:  DusterIdiot [ Wed Aug 29, 2012 5:39 am ]
Post subject:  Yep...
Quote:
A special dizzy for a 76 manual tranny? Seriously? If its all just weights & springs and a vacuum advance why not just install MSD for a complete burn, which is what I'm assuming they were doing mechanically.
You could do that...but the distributor curve hinges on a lot of vacc. advance almost all the time...
Quote:
although some suggest with the longer iron tailshaft that I swap the gears, dogs, and selectors into the shorter shafted 833 for better ratios.
I would use the shorter shaft version to save some weight (I use them because my feather dusters came with them)...Also, I'm not sure what you imply by better ratios...the truck version has the same ratios as the car version, just a different gear pitch...

Quote:
Napa should have access to the EGR?
No, you'll get a generic EGR...NOS would be the only way to get the correct larger orifice version (basically it should allow a lot of exhaust gas back into the intake charge to combat ping from all the advance and effectively reduce the actual displacement of the engine by taking up combustion space with inert/spent gasses). Dan at one time had posted a modular EGR that you can swap orifices on and see which one is closer to "stock" for this particular model.

-D.Idiot
Author:  Aluminum Six [ Wed Aug 29, 2012 5:40 am ]
Post subject: 
I've also forgot to mention in reading someone for flow reamed the exhaust manifold to 2.25 inches after removal of the heat flapper to direct heat at the floor of the intake. They cut out the flapper. I know where to find a new one, as removing it in reusable shape is fubar, two tiny screws hold it to a shaft that one side has a groove for a retention spring and the other is a pressed on weight.
Author:  Aluminum Six [ Wed Aug 29, 2012 3:22 pm ]
Post subject: 
The gear ratios were a post on this site's old board. I googled switching lonshaft iron for sort shaft aluminum and found a complete tear down and swap was the implcation, however they were referring to a newer 833 because the one subject to speculation was a top loader from a power wagon and mine is just a simple d-100 2 different triangular shifter mounting bosses.

Is there a part number for the '76 manual EGR and dizzy?
Author:  DusterIdiot [ Wed Aug 29, 2012 8:48 pm ]
Post subject:  Here
Distributor 3874795/796
EGR 4026261
Vacc. Switch 3879736
Carburetor 4006643/4 R-7562-A R-7559-A (aka Holley 1945)
Quote:
the one subject to speculation was a top loader from a power wagon
Top loader is an NP235/435 granny gear tranny...good for hauling loads, not my favorite for getting around, really heavy and not fun to play with...no relation to the A-833/OD, and neither shares each other's bolt patterns on either bellhousing...(I'm working on an adaptor to solve that...)

-D.Idiot
Author:  Aluminum Six [ Thu Aug 30, 2012 9:45 am ]
Post subject: 
I have 2 aluminum bellhousings, one drilled for an 833 and the other has a dual or maybe triple pattern.
Author:  Aggressive Ted [ Thu Aug 30, 2012 10:22 am ]
Post subject:  Feather Duster tire diameter
Does anyone have the specs on the tire diameter for the Feather Duster cars?
Was it 26" like a E70 14? or a P215/70R14?

Just curious with the 2.76 gear ratio....

With my 74 Swinger and 904 automatic it is hard to break past the 26 mpg barrier. Running weight most of the time is 3600 pounds with a full tank and me in it...
Author:  Aluminum Six [ Thu Aug 30, 2012 12:55 pm ]
Post subject: 
OoooOh wow man my Malibu has 195/70/r15's and I get about 33mpg, but the tires have a 44psi limit apposed to 36 which jiffy lube thinks is the correct air - I ride a road bicycle with 130psi Bontrager dual compounds. With a 1/4 inch of vertical tread in contact with the road I know the second one goes low.

Maybe that helps?
Author:  Aluminum Six [ Thu Sep 05, 2013 6:00 am ]
Post subject:  Holley 1945
Is it that simple, or is it in need of tweaking the circuits, also the vacuum EGR system, is it electronic, and run off the temp sensor? Or does it have a thermistor?

Also, reaming the inside of an exhaust manifold's throat improves flow, but hedders do as well, but is that performance flow or mileage flow and with no heat to the intake, will gasoline pool up on the floor?
Author:  Aggressive Ted [ Thu Sep 05, 2013 8:52 pm ]
Post subject: 
Quote:
run off the temp sensor
It runs off a radiator switch. There is a bung in the radiator tank for it.

You can emulate the Gold Duster, my best friend had one and it did get 36 mpg from Bellingham, WA to Portland, Oregon and back, but it sure was gutless.

On my 74 I started to go that route but eventually ditched all that, and went with the aluminum one piece cast intake (it warms up much quicker), added a heat deflector to help keep the manifold warm and carb cold, ditched the stock fan and went with electric ones to let the intake warm up faster, and instead of the EGR use water injection to knock back the timing over 2000 rpm. I run 55 degrees of timing....I also got rid of the flapper augured out the exhaust for about 6 inches to match the 2.25" flange, ran 2.5" exhaust all the way back through two FlowMasters (super quiet exhaust). My car gets great mileage for having an automatic and for its body shape and weight. I don't drive it easy either, but use a vacuum gauge to monitor how bad I am....It is really spunky and fun to drive.

Click on the red link to view pictures.

So you are almost here..... :D :D :D
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