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Question about emissions and transmission option
#1
Wrench 
Hi there.. it's me, asking so many questions again, but just trying to educate myself as much as possible before I invest into my Mach 1. My "third" car garage will be ready this weekend after it is epoxy sealed.

In any case, I have two more questions:
1- Is there any difference in regards to emissions between 71, 72 and 73. I hate this emissions stuff and vacuum lines running everywhere. Have you guys removed some of it?
2- Auto transmissions: C4, C6, FMX. Should I worry about which one? I have read that FMX's are heavy and with no too many aftermaket parts, but at the same time they are strong. C4 and C6 are light and with more aftermarket parts.

Thank you again for the wealth of information you guys share.
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#2
tony-muscle;194143 Wrote:In any case, I have two more questions:
1- Is there any difference in regards to emissions between 71, 72 and 73. I hate this emissions stuff and vacuum lines running everywhere. Have you guys removed some of it?

There are some emissions differences between the three years, the most restricted of the three is 1973 because of the strict regulations that came into affect at this time.

In terms of removing all of it, that's accomplished quite easily. The EGR valve can be removed and a block-off plate installed. And then the only vacuum line required is for the distributor (as well as supporting vacuum accessories such as the power brakes, air conditioning, and transmission) This effectively removes the exterior portions of the emissions system. There is also the vapor recovery system for the fuel tank, which is a small canister mounted on the passenger side wheel tub, which has a return line to the gas tank, and is connected to the engine via the air cleaner with a small tube. Again easily removed.

Internally there are some difference, the compression ratio for the engines of each year are slightly different as Ford responded to the emissions requirements. There's a better explanation of that posted in a different thread here on the board.

These engines were never equipped with smog pumps to my knowledge.

2013 Ford Focus SE Flex Fuel 5spd - Daily Driver
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#3
I wouldn't worry about which auto transmission the car has.

Factory would be FMX or C-6 both are strong, the FMX is a little heavier than a C-4 due to the cast iron case, but we are talking 10-15 pounds or so. The best upgrade to many of these cars is a more modern overdrive 4 speed automatic-this allows gearing that will perform well off the line and reasonable highway mileage. Oddly enough an AOD weighs the same amount as an FMX.

If you plan to build an engine, the smog stuff is easily removed. Some of it like the vapor recovery canister isn't necessarily a bad thing to keep intact.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#4
Funny thing about the vapor canister, my son blocked the canister with a plug as he put a chrome aftermarket air cleaner on. The gas cap is non-vented. So he went to put gas in one day and the cap literally popped off when he gave it a twist. He said it flew across the parking lot (doubtful but he probably thought everyone saw it). I started checking into it and discovered that he plugged the vapor cannister. I took the plug off and left it to atmosphere. So far no further gas cap incident.
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#5
tony-muscle,

I am with MechEng and Jeff73Mach1 on the transmissions and most of the emissions equipment removal. The vapor recovery system for the fuel tank might be considered to leave intact. One of the reasons why is,

The Evaporative Emission (EVAP) system prevents fuel vapor build-up in the sealed fuel tank. Fuel vapors trapped in the sealed tank are vented through the vapor valve assembly on top of the tank. The vapors leave the valve assembly through a single vapor line and continue to the EVAP canister,located in the engine compartment for storage until the vapors are purged to the engine for burning.

[Image: 2ikqhr4.jpg]

Source: Ford master Parts Catalog, Copyright, May 1975

mustang7173
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#6
The AOD is essentially (not exactly) the next-generation FMX... but with overdrive. The overall exterior dimensions are the same, the gear ratios (with the exception of OD) are the same, and the FMX will bolt-up to any FMX-equipped small-block application with a simple change of the flex-plate (from .27oz to .50oz balanced flex-plate).

The main differences:
  • flex-plate balancing (FMX: .27-ounce; AOD: .50-ounce)
  • Pan size (AOD is a bit bigger)
  • TV cable
  • Shift linkage (will require an adapter while using stock shifter)
  • output shaft yoke size - you'll need an 'adapter' U-joint to work with stock driveshaft
  • mounting bracket - needs modification to work with AOD or aftermarket bracket
  • cooling lines are somewhat different - will need custom lines for the AOD
  • neutral safety and reverse switches are internal to AOD... but on the shifter for FMX

I have an AOD conversion in mine - it was pretty easy, with a couple minor things discovered along the way.

I mentioned that in case you were interested in swapping the FMX for something more modern - you are correct: aftermarket support for the FMX is very limited. Others here have swapped in AODEs and 4R70W automatics with great results.

Eric

[Image: mach1sig2.gif]
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#7
Thank you.... it makes sense to leave the EVAP system on. I am more concerned with whats connected directly to the engine.
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#8
1) 73 has the most restrictive emissions, however California had massive emissions requirements before most of the country so a 71,72 Cali car can be equipped with all kinds of crazy smog pumps and EGR valves and delay spark vacuum servos.

from an emissions standpoint a 71 non-cali car is going to be the least restrictive. in 72 gov standards started to kick in mid production cars had changes to the engine open chamber heads, and reduced engine choice combinations, they started to detune the cars. in 73 things really locked down and the emissions restrictions really started nation wide.

if you want a real non-emissions car then you should focus on 1971 models, closed chamber high compression heads V4 4bbl cars Q codes, R codes, M codes, SC, SCJ cars.

1a) Not all emissions stuff is a bad thing.

* PCVs are a very good thing, you want a car with the PCV working. it produces negative pressure in the crack case and stops or reduces oil leaks, stops varnish build up in the heads and removes water from the engine.

* fuel vapor canisters are a very good thing also, they vent the tank remove water and get rid of fuel smell. your fuel tank won't get rustly and varnish won't clog up the vapor return lines.

* Distributor Vaccum Control Valve (DVCV) is another good thing that switches a motor from ported to full mainfold vacuum when the car overheats it increases RPM and advances timing and helps cool down the engine.(its a last resort measure)

2) The FMX and C6 are the same gearing, the difference is the C6 is much lighter then a FMX. the design on both transmissions is different but the gearing for all 3 gears is the same.

The C4 is a good transmission it was mainly for lower displacement like the 302 motors they claim the C4 is good to 400HP while a C6 is good to 600 HP.

a lot of drag guys use built up C4s and claim they drop a little time compared to a C6. they say the C4 is lighter.

For the most part you see C4s on 302, FMX on 351 2bbl cars and C6 on 351 4bbl cars. the hot ticket would be a 351 mated to a C6.

i have a 1972 2bbl originally with a FMX that was rebuilt to a 4bbl with a C6 trans i have open chambered head. so from a performance standpoint it is not ideal does fine on the street.


tony-muscle;194143 Wrote:Hi there.. it's me, asking so many questions again, but just trying to educate myself as much as possible before I invest into my Mach 1. My "third" car garage will be ready this weekend after it is epoxy sealed.

In any case, I have two more questions:
1- Is there any difference in regards to emissions between 71, 72 and 73. I hate this emissions stuff and vacuum lines running everywhere. Have you guys removed some of it?
2- Auto transmissions: C4, C6, FMX. Should I worry about which one? I have read that FMX's are heavy and with no too many aftermaket parts, but at the same time they are strong. C4 and C6 are light and with more aftermarket parts.

Thank you again for the wealth of information you guys share.
  Reply
#9
The FMX is a pretty robust transmission due to many of the internal parts being machined not stamped like the C-4 and C-6.The cast iron case helps as well. They are a bit more complicated to rebuild and share the same "compound planetary gear design as the AOD. The FMX in my 72 is untouched except for a fluid change and has 153 K miles on it. The 358 pound feet of torque has not phased it as of yet.
Ron
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#10
The search for 4 speed auto is killing me
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