Engine What is a de-smogged 304 entail?

[1979GabeCJ5]

So, I have an AMC 304 (1979) so when I got it, it was partially plugged up, de-smogged, etc….

It has 3/8 MIP plugs on 3 places (2 removed currently) on the intake manifold. All 3 of the plugs had vacuum hose nipples (one had 3) on them that were rubber-cap plugged. Then there’s a weird cylindrical apparatus that says “AH”

What should be plugged? Is there a way to find the parts from the original vacuum/distributor “harness” that I’ve heard of? Should I just leave it plugged? I don’t think it’s a California vehicle.

Any guidance would be appreciated.

 

[Manic Mechanic]

That looks like EGR and other EVAP component locations. I have a 79 AMC 304 at home I'll try to remember to get some pictures of the motor when I get home.

If it's running and you don't need it to pass emissions where you live then I wouldn't worry to much about it

 

[1979GabeCJ5]

That looks like EGR and other EVAP component locations. I have a 79 304 at home I'll try to remember to get some pictures of the motor when I get home.

If it's running and you don't need it to pass emissions where you live then I wouldn't worry to much about it

So one of them is some kinda coolant sensor after some googling. Should that stay plugged?

 

[Manic Mechanic]

Sorry for the bad pics

 

[1979GabeCJ5]

So I guess we’re twins in this regard. I just got some fancy 3/8th plugs for the other ports

 

[Manic Mechanic]

I'm going to plug off everything that I don't need

 

[1979GabeCJ5]

So guys, I gotta question about timing… could I pick y’all’s brains on this?

 

[Manic Mechanic]

Yes

 

[1979GabeCJ5]

Yes

Okay, so I got this thing running but it’s running rough. I got my timing light I got marks on the crank, etc.

The problem: when I’m turning the motor by hand, when I reach TDC of the compression stroke, the dist. button is point directly at #1 but if I continue to turn the motor, I find that TDC of the EXHAUST stroke is not 180° from that of the TDC of compression.

Here’s two pics: the first is TDC of compression, the second is TDC of exhaust… bear in mind that I’m a novice at best with ignition timing.

Should TDC of Exhaust and TDC of intake/compression be 180° apart?

I’m having a big brain fart.

 

[Manic Mechanic]

Engines vary wildly. I know the AMC 258 i6 / 4.2l really likes about 9⁰ before TDC the AMC 304 around 10-12⁰ before TDC. So if you're at TDC and right on cylinder 1 then that means your at 0⁰. You need advance your timing. Start by making sure that you have no vacuum leaks. Then start your engine and and rotate the distributor slowly until it idles better.

I tend to do this with the vacuum advance disconnected.

 

[1979GabeCJ5]

Engines vary wildly. I know the 4.2 really likes about 9⁰ before TDC the 304 around 10-12⁰ before TDC. So if you're at TDC and right on cylinder 1 then that means your at 0⁰. You need advance your timing. Start by making sure that you have no vacuum leaks. Then start your engine and and rotate the distributor slowly until it idles better.

I tend to do this with the vacuum advance disconnected.

Advance is counter clockwise correct?

 

[Manic Mechanic]

To advance the timing on an AMC 304 , you must turn the distributor counter-clockwise. This is because turning the distributor housing in the direction opposite to the rotor's normal rotation advances the spark timing.

 

[jzak]

On my AMC 258 i6 / 4.2l CJ5 I removed the charcoal canister and circumvented the check and rollover valves with a pair of boat aluminum vents from Amazon.

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