1974 225 Emissions questions

[moparbud66]

I just installed a real nice running 74 225 into a 73 Dart Swinger. While the engine was out, I removed the emissions system for painting and new gaskets. Now I'm wondering if I should reinstall these components or leave them off. They include a resistor block that the electric choke connects to, a vacuum amplifier, another vacuum/electric relay of some sort as well as multiple vacuum lines and a couple of plug in boxes, one on the firewall and one on the DS fender well. It also has an EGR valve in the exhaust. Will it run better or worse if they are left off? or should I just reinstall everything and keep it original. I'm assuming the 73 system was different as there was a small vacuum "box" on the firewall where one of the electrical ones is on the 74. I believe vacuum went through this box before it went to the distributor. The 74 does not have vacuum advance on the distributor. Do those little boxes somehow control the timing? If I leave this stuff off, should I remove the EGR and block it off with a plate? What have others done?

 

[halifaxhops]

I pulled all mine and did the egr plate. The choke timer box you might want to keep to save the life of the choke though, personal choice. Ran about the same.

 

[slantsixdan]

a resistor block that the electric choke connects to

You need this or the choke won't work correctly, unless you improve things (a lot) by installing a new Electric choke kit.

a vacuum amplifier

Necessary if you're keeping the EGR system operational.

another vacuum/electric relay of some sort as well as multiple vacuum lines and a couple of plug in boxes

Plowing through the engine bay yanking and cutting and disabling stuff because "That's a pollution control, so I'ma git rid of it!" is a thoughtless and unreasonable thing to do. See here for info on what the various systems are and which ones are worth keeping vs. removing.

there was a small vacuum "box" on the firewall where one of the electrical ones is on the 74. I believe vacuum went through this box before it went to the distributor.

That's the OSAC valve, notorious for causing mushy driveability/hesitation. Bypass it (hose directly from the correct port on the carburetor to the distributor).

The 74 does not have vacuum advance on the distributor

It did originally -- perhaps someone dropped in a (much) later "Lean Burn" distributor. You definitely need vacuum advance for good driveability, performance, and fuel economy, so either swap the '73 distributor into the '74 engine, or get a new distributor from Old Car Parts Northwest as described in the HEI upgrade article.

 

[moparbud66]

You need this or the choke won't work correctly, unless you improve things (a lot) by installing a new Electric choke kit.



Necessary if you're keeping the EGR system operational.



Plowing through the engine bay yanking and cutting and disabling stuff because "That's a pollution control, so I'ma git rid of it!" is a thoughtless and unreasonable thing to do. See here for info on what the various systems are and which ones are worth keeping vs. removing.



That's the OSAC valve, notorious for causing mushy driveability/hesitation. Bypass it (hose directly from the correct port on the carburetor to the distributor).



It did originally -- perhaps someone dropped in a (much) later "Lean Burn" distributor. You definitely need vacuum advance for good driveability, performance, and fuel economy, so either swap the '73 distributor into the '74 engine, or get a new distributor from Old Car Parts Northwest as described in the HEI upgrade article.

Thank you Dan, I was hoping you'd chime in. I was reading some of your old posts regarding all of this. I think I will leave everything intact as the engine was running great. I could be mistaken about the distributor but will check again and get another if I need to.

 

[BillGrissom]

The choke timer is good for opening the choke faster, so you don't run rich. EGR will generally make the engine run worse, even when working perfectly. EGR reduces NOx, which is beneficial in crowded areas w/ stagnant air (L.A. Basin), but won't hurt anybody in Seneca and is no long-term threat to the earth's air. Keeping EGR will lower your mileage, giving more CO2 emissions, which is a long-term threat (google "Al Gore"). A block-off plate is $15 on ebay. Very hard to insure any of the vacuum emissions controls are working today, and nobody should expect you to do so. Best long-term is to replace the carburetor w/ fuel injection, w/ throttle-body being the only bolt-on option for a slant and requires a 4-barrel intake. One TBI system is now under $1000, w/ used kits much less on ebay.