Emissions Testing - 1968?

[somethingspecial]

imco v. thermactor

I have been looking in all my literature, and the best I can determine, All A/T cars had Imco, and all M/T cars came with Thermactor. Of Course, there are exceptions to every rule. Changes or shortages at the assembly may cause deviation at time of assembly. But several sources were checked before this post, and they all concure, Imco for auto, Thermactor for manual, and this is 289,302. When you get into the 390,428 family, thermactor was across the board, A/T or S/T. I know someone will disagree with me, but that is what my research has come up with.
On a side note, I checked with the local Ca. Highway Patrol office, and they told me that 68' is totally exempt from any smog in Ca. You don't have to get a smog cert. when registering, and is not subject to inspection. Ca. owners do not have to worry about being cited if they don't have any smog equipment on the vehicles. Run what you desire, intake, headers, etc. You will need a PCV valve however. Hope this helps. Mike

 

[case12]

You don't have the PVS (ported vacuum switch) on the therostate housing that controls the vacuum advance at the dist? That was part of the IMCO system used on cars like J codes with automatics

Umm - I am not sure - sorta ignorant in this area. I have a 289 - But an edlebrock intake and 4 barrel were added. (I have the original intake and 2 barrel carb in a box) Air cleaner is original, and has the tube down to the exhaust. I am not at home to look at my books to remember what a therostate or IMCO are. Casey

 

[Mosesatm]

The ported vacuum switch from the IMCO system is just the contraption on the thermostat housing that the 3 vacuum lines hook into. Attached is a picture of one.

 

[J_Speegle]

J Speegle,
Was IMCO used on all 289, 302 engines in '68, with either manual or auto transmissions? My GT/CS is a Canadian car, ordered with Canadian Non-Emmision System. It has a 289 2V/ 3 spd manual. Would it still have IMCO?

Not sure (don't so much with Canadian cars) but I would guess that the IMCO system would have been included since without it there would ahve been timing and runability issues. I know in later years it was included since much of the system was bulit into the engine and the parts.

 

[case12]

As an update, I asked Haggerty for an endorsement showing that my car was a show car driven less than 3000 miles a year (I probably drive less than 100 miles anyway). Sent it to Illinois EPA per instructions and they gave me an emissions waver. Problem solved (for 2 years until I have to do it again).

Arlie, I looked at my air cleaner and it does have one nipple for a hose that is no longer there. I couldnt fine 3 of anything. Since I am ignorant of emissions, does anyone know where the hose from the air cleaner would go? (just under the air snorkel and a small "can" through which presumably the air passes).

Casey

 

[BroadwayBlue]

one of these hoses?

I'm curious to understand as well...

 

[Mosesatm]

I've unhooked mine to get the air cleaner off but have never looked to see where it goes. I'll get a picture of it tonight for you.

 

[p51]

Arlie, I looked at my air cleaner and it does have one nipple for a hose that is no longer there. I couldnt fine 3 of anything. Since I am ignorant of emissions, does anyone know where the hose from the air cleaner would go? (just under the air snorkel and a small "can" through which presumably the air passes).

Casey

[Note: Inaccuracies may follow. I'm not completely sure of this]. There is a cap on the valve covers (right one as you face the engine) that vents blowback gas (that leaks pas the rings into area under the valve covers) into the atmosphere. In 1968 to help with emissions the cap was changed to have a hose attached to it (as well as a filter in the cap). The hose goes to the air cleaner so that the blowback gas is recycled and burned. Hence you reduce emissions. My understanding is that this simple change actually decreased pollution by a significant percentage and followed the 80/20 rule - 80% of the gain for 20% of the effort.

 

[p51]

[Note: Inaccuracies may follow. I'm not completely sure of this]. There is a cap on the valve covers (right one as you face the engine) that vents blowback gas (that leaks pas the rings into area under the valve covers) into the atmosphere. In 1968 to help with emissions the cap was changed to have a hose attached to it (as well as a filter in the cap). The hose goes to the air cleaner so that the blowback gas is recycled and burned. Hence you reduce emissions. My understanding is that this simple change actually decreased pollution by a significant percentage and followed the 80/20 rule - 80% of the gain for 20% of the effort.

Hmmm... ignore my last post. Just looked at the pics in the thread. Pretty clear you guys are talking about yet another hose hooked to the air cleaner (which I dont happen to have on my car). Sorry 'bout that...

 

[Mosesatm]

I hope we're talking about the small-diameter hose that hooks to the underside of the snorkle. It's the annoying little one that always keeps the air cleaner from coming off until you tilt it up and unhook the hose.

 

[Mosesatm]

This doesn't address the hose issue but this looks like a good website for smog control part information.

http://www.thecoralsnake.com/smog.HTML

 

[case12]

I hope we're talking about the small-diameter hose that hooks to the underside of the snorkle. It's the annoying little one that always keeps the air cleaner from coming off until you tilt it up and unhook the hose.

Yes, that is what I was talking about. Doesnt look like what Rich posted. Casey

 

[GTCSMustang]

For cars built before 4/2/1968 there is a vacuum override motor attached to the underside of the mixing duct. It is connected to the rear of the intake manifold by a blue stripped rubber hose.

Scott

 

[BroadwayBlue]

Yes, that is what I was talking about. Doesnt look like what Rich posted. Casey

I didn't know what I was posting so I took shot with a full engine view :grin:
I'll try to get a picture under the air cleaner tonight or tomorrow.

 

[case12]

Here are the pics. Sorry for trying to describe it and make everyone guess. A picture is better. Scott, is this what you are referring too? I have an aftermarket Edlebrock intake, so would it have the hose connected. I am just curious. (I didnt realize the bottom side of my air cleaner was so dirty - I am embarrased now) Casey

 

[GTCSMustang]

Casey,

You don't need to connect it if you just want the leave it the way it is. But normally it would be connected to a fitting at the rear of the intake manifold. See picture. You would need to add this fitting to yours.

Scott

 

[Mosesatm]

Casey,

You don't need to connect it if you just want the leave it the way it is. But normally it would be connected to a fitting at the rear of the intake manifold. See picture. You would need to add this fitting to yours.

Scott

That's interesting. Here is where it is attached on mine. Other hoses seem to be attached to the block in the back on my engine. Oh well, it'll go on the list of things to fix.

A long time ago I wrote down where the 3 hoses go that are attached to the front junction block on the thermostat housing. Now I'm not sure what it means.

Does this make sense to anyone?
Top Hose - Carb
Middle Hose - Mistributor - advance side
Bottom Hose - Manifold - retard side

 

[GTCSMustang]

Arlie,

Do you have any plugged or capped ports on the block at the rear of the intake manifold?

Scott

 

[case12]

Thanks Scott - last question (I think) - what does the little canister on the air cleaner do? control the flap? If so, do I need to do anything with the flap, or is it pretty much open when the hose is not connected. Back in my Mopar days I remember having one of these flaps on my Charger air cleaner that I believe was heat activiated? Again, I am not an emissions expert.

Arlie, nice stick :grin: Is that original equipment:icon_no: (seriously, thanks for the picture) Casey

 

[GTCSMustang]

Under hard acceleration, the vacuum motor allows more cold air to flow into the air cleaner by closing the air source from the "S"-tube. Yours should have a spring that allows the flap to default to the "open to the S-tube" position. By the way, it should not be painted like your is.