My Engine runs ALRIGHT, but not Well. When i first got the car, I gave it a Tune up. New Distributer, Cap, Coil, Rotor, Wires, and plugs. It ran much better after that, but it still has a miss. This Engine is off the grid as it were. There is no computer control AT ALL. It's got an aftermarket carb with a vacuum advance aftermarket distributer. everything else is stock. This is a 305. It originally came with a quadrajet. AC is Disconnected.

The guy i got my 9 bolt from on Craigslist has a temperature gun. I asked him to take a look at my car quickly and see if he could nail down my problem. he check the Carb........ Okay. He then grabbed that gun and shot it at my Exhaust manifolds near each spark plug. Numbers 4 and 6 were much cooler than all the other cylinders. At that point, he told me that's all he could do for me.

I figured i would start with the Obvious. I went to Wal-Mart and bought a pair of New Spark Plugs. I replaced the old ones and the ones i took out LOOKED fine. My Camera can't really take a nice enough picture for me to show you what they looked like, but they don't look bad. In addition, the car still runs the exact same way.

Any Ideas?

 

Here's the Closest shot i can get of one of the old spark plugs.

 

How much cooler?
You know the #4 and #6 exhaust ports have the extra ports that feed the exhaust heat crossover/EGR passage in the intake manifold. The exhaust flow characteristics are changed a bit on those ports, especially if EGR is active, you have a malfunctioning/leaking EGR valve, or an internal EGR leak between the head port and the intake manifold.

I recommend further troubleshooting other than the thermometer gun. That plug doesn't indicate a dead cylinder.
Taking a close look at all the spark plugs may be a good start if you're looking for localized misfires.

 

IIRC it was like 30 Degrees. The car has no Computer. Does the EGR still apply? I may have to pull the other plugs. I'm not looking forward to pulling the back two Plugs. If the Computer is gone and the EGR is still hooked up, Would that potentially cause a problem?

 

Could it simply be a worn out Valvetrain? Because i'm pretty sure THAT condition exsists. If i were any good at Valve Lashing, i would re-lash the valves. Even still......... The springs could be too warn for that to do any good.

 

Leaking of the EGR passage at the valve or at the head/intake interface can happen even if the EGR isn't functioning. It's just a possibility I wanted to mention.
Yes, checking the valvetrain wouldn't be a bad idea.
Look for broken springs or collapsed lifters.

There is still a multitude of possibilities since your description of the problem is rather vague and very little troubleshooting has been done so far.
You have to start somewhere though.
Have you testing manifold vacuum yet?

Did you set up your new distributors centrifugal and vacuum advance mechanisms properly?

 

Yes, i do have some trouble shooting to do. I haven't tested Manifold Vacuum and i don't think i have that Equipment. The Distributer was installed by a local repair shop. The car had the Electronic Controlled Distributer when i bought it and i figured it would be a good idea to get that taken care of very soon, so i sent it to someone that knows what they're doing. I think that i'll have to do some more testing. In the mean time, it's drivable, but it's not my DD.

 

Are you sure about that? Most shops arent really experts at setting things on a 29 year old car with aftermarket parts. Who knows how they have your timing set up. Even if they have a reputation for being knowledgeable about muscle cars, every car and every engine has different spark advance needs. It's really recommended to spend the thirty dollars on a timing light and learning to check it yourself.

 

I have a timing light, but there is no Timing mark on the engine......... At least not that i can see.