My 83 Trans Am has the LG4 305, and its got about 233,000 miles on it. I got the car about 2 months ago and the guy swore up and down the engine was rebuilt, but I knew better. but it wasnt my main concern when my plan was a 350 swap anyway.

But due to set backs getting a 350 around, I need this 305 to last a bit longer. Two of the lifters were collapsed and making a racket. I verified them by using a short length of rubber hose and holding it on the rocker arms stud of each cylinder and holding my ear to the end.

So I bought a couple lifters and gasket set and went to work.

I got the two lifters out with a bit of work due to the build up on the bottoms that was holding them in. I made sure to soak the new lifters in oil for about 30 minutes moving them around a couple times to make sure they were full of oil, even used a phillips to plunge them in and out under the oil to be sure. Then I lubed them with assembly lube and stuck em' in.

I noticed that the old lifters were concaved, so I'm sure the outsides of the cam lobe were worn down. At this point I had little to lose.

After installing the lifters I went back and re-adjusted lash on all lifters.

The car started up perfect but two lifters were still clattering, so I adjusted them hot, but one of the two I replaced would not stop clattering which was kinda strang. I went so far as twice the spec and still was clattering. so I shut if off and got back to TCD and readjusted it to stock sped without it running. Even with the new lifter it was still clattering, so I am at a loss to explain the problem.

Also since doing this work, the engine is smoking a lot with heavy acceleration. I'm tired of messing with this worthless engine and I'm not willing to dump anymore money into it so a new cam is out of the question.

My main question is: what could be causing the sudden smoking issue(its bluish gray), and why would a new lifter be clattering worse than the old worn out one?

I used "Sealed Power" brand lifters so dont worry they arent ebay crap.

I did notice that all the push rods were spinning along with their respective lifters except the one where I replaced the lifter. So I wonder if the lifter is spinning like it should be and if not, can that cause it to not maintain lash.

I'm fed up with it enough at this point that I threw a quart of ATF in the engine oil to try and clean the tarnish and sludge that was built up on about everything. Hell the drain hole to the timing chain was almost completely blocked off. I cleaned what I could get to, but this engine is shot.

 

If the lifters were concave, the cam needed to be replaced.

 

And since the cam needs to be replaced (which it DEFINITELY does), you'd want to throw the engine away, since it's all full of metal now, and it's an LG4.

The smoking is your intake gaskets, likely, if it's surely a new problem. Unless the clattering is a cracked piston or ring. If you really got a lot of oil all over the springs and valve stems, it might be some of that.

 

I have figured out the smoking issue. So simplistic its frightening.

The horrible smoking that the engine was making on hard acceleration was not anything I did wrong, it was simply caused by oil getting in the valve guides. today I checked the oil and it was low due to a bad valve cover gasket, and after I poured in the oil the car was just billowing smoke, and then it started to fade. After 100 miles without adding oil the smoking is gone. So I just need to replace the valve cover seal so I dont have to keep dumping in oil.

And on the lifter issue. I ran a quart of ATF in the engine oil for about 50 miles, drained it, and refilled with 20/50 oil and the clattering is almost gone when hot, but it does still clatter bad when cold and warming up.

 

Plugged oil passage to that specific lifter? After the new one started making a racket, that would be my first guess. Especially if the rest of the motor is as bad as you say. Also, plugged returns on the head will allow oil to pool in the valve cover and will dump an excessive amount into the cylinders.

You said things were gunked and almost plugged...well, this is the result. Outside of some engine-cleaner-in-a-bottle(ATF works well enough), I wouldn't put much money in that thing either.

By the way, I pretty sure that 20/50 oil isn't helping any. Most other street motors run between 5/30-10/40. If the oils too thick, it can't get through the oil passages quickly enough. If you passages are gunked, it just makes it worse.

FWIW, I run 10/30 on my worn out 305, and I've never had any oil issues.