Question about lifter condition, effect on the engine. It's a '70 Chevelle 350 put in by the first owner. Second owner did some cosmtetic stuff, added Edlebrock cam and carb. The engine was so clean you could eat off it.
I've revised the purpose of the question for clarity, now.
The initial input I received was about consequences of the problem and steps forward, which was valuable info to me.
In my original post, I wanted hear speculation on how it happened. As noted, my original thought was that one way or the other, valve spring pressure was the culprit. Either that or just plain old excessive lash after a valve job.
My engine is ruined from a bad lifter/cam lobe that I never heard before the valve job and I'm looking for answers.
Here is my guess as to the cause.
If there was no tap before the valve job, my (amateur) guess is that this one valve was not adjusted and the lifter banged against the cam, resulting in what you see. That would explain why 14 lifters look fine, one is kinda bad and one is horrible. The engine has never been taken apart. If that's the case, this would have need to have occurred over about 500 miles of max 3000 rpm, every now and then, 4500. Last oil change used 20w50.
This could also have been a minor problem, undetectible before, made worse after the valve job, due to poor adjustment. A few thousand miles earlier, compression was within range on all cylinders.
Circumstances
I did not hear any kind of a valve tap prior to a valve job to replace guides/seals. The Head rebuilder said they were fine, spark plug fouling due to too large of carburator. (Expert in Honolulu put an Edlebrock 750 on a stock '70 Chevelle 350 and it's not possible to have sustained high rpm on Maui).
Thoughts?
Original post
Lifter pics attached. One is really cupped, one not near as much, four with the same minor wear pattern and the others, flat. I can't see an acceptable format to upload a video so you can hear the engine...
I think cupping like that is due to valve spring pressure, not a bad cam, which my mechanic said was the problem. Engine ran really smooth a couple thousand miles ago but.. some changes since then..
1. My question is, with that much cupping, is it likely that this lifter was making the a lifter sound before and I didn't hear it?
2. I'd say this lifter wear took a long time. I don't think that could happen with only 1000 miles after the heads were rebuilt (to solve a bad spark plug fouling problem. The Head rebuilder said heads were fine, engine solid, the carb was too big fouling the plugs, not oil)
3. Would this lifter prevent it from running smoothly? (It purred before the valve job if spark plugs were fresh)
4. Could this valve/spring be adjusted to compensate for the wear, if it coulld be isolated during a valve adjustment, prior to replaceing the lifters?
4. I didn't hear a valve tap before the heads were rebuilt but I did after and now moreso after new lifters were installed! Hard to say with a new exhast leak on one side, at or near the exahust manifold. (That's how the mechanic gave it back to me). But now I hear the tap on both sides when it was mostly one side before.
The engine does run much more smoothly after the lifter replacement, very close to how it ran with the too-big carb and fresh plugs.
This guy obviously is done working on the car since he gave it back to me like this.. he did not charge for the lifter replacement, possibly because no matter what he does, problems come up in completing any job all the way. There is a history of carb problems, I think starting with when they first touched the car (and crashed it during a compresson test two weeks after I bought it)..this has been a tough road..
My next step is to change the oil, which was not done along the way...
I'd appreciate your input. I wish this was a simple whats the deal with the lifter but the sequnnce of events and contiions complicate it.
I've revised the purpose of the question for clarity, now.
The initial input I received was about consequences of the problem and steps forward, which was valuable info to me.
In my original post, I wanted hear speculation on how it happened. As noted, my original thought was that one way or the other, valve spring pressure was the culprit. Either that or just plain old excessive lash after a valve job.
My engine is ruined from a bad lifter/cam lobe that I never heard before the valve job and I'm looking for answers.
Here is my guess as to the cause.
If there was no tap before the valve job, my (amateur) guess is that this one valve was not adjusted and the lifter banged against the cam, resulting in what you see. That would explain why 14 lifters look fine, one is kinda bad and one is horrible. The engine has never been taken apart. If that's the case, this would have need to have occurred over about 500 miles of max 3000 rpm, every now and then, 4500. Last oil change used 20w50.
This could also have been a minor problem, undetectible before, made worse after the valve job, due to poor adjustment. A few thousand miles earlier, compression was within range on all cylinders.
Circumstances
I did not hear any kind of a valve tap prior to a valve job to replace guides/seals. The Head rebuilder said they were fine, spark plug fouling due to too large of carburator. (Expert in Honolulu put an Edlebrock 750 on a stock '70 Chevelle 350 and it's not possible to have sustained high rpm on Maui).
Thoughts?
Original post
Lifter pics attached. One is really cupped, one not near as much, four with the same minor wear pattern and the others, flat. I can't see an acceptable format to upload a video so you can hear the engine...
I think cupping like that is due to valve spring pressure, not a bad cam, which my mechanic said was the problem. Engine ran really smooth a couple thousand miles ago but.. some changes since then..
1. My question is, with that much cupping, is it likely that this lifter was making the a lifter sound before and I didn't hear it?
2. I'd say this lifter wear took a long time. I don't think that could happen with only 1000 miles after the heads were rebuilt (to solve a bad spark plug fouling problem. The Head rebuilder said heads were fine, engine solid, the carb was too big fouling the plugs, not oil)
3. Would this lifter prevent it from running smoothly? (It purred before the valve job if spark plugs were fresh)
4. Could this valve/spring be adjusted to compensate for the wear, if it coulld be isolated during a valve adjustment, prior to replaceing the lifters?
4. I didn't hear a valve tap before the heads were rebuilt but I did after and now moreso after new lifters were installed! Hard to say with a new exhast leak on one side, at or near the exahust manifold. (That's how the mechanic gave it back to me). But now I hear the tap on both sides when it was mostly one side before.
The engine does run much more smoothly after the lifter replacement, very close to how it ran with the too-big carb and fresh plugs.
This guy obviously is done working on the car since he gave it back to me like this.. he did not charge for the lifter replacement, possibly because no matter what he does, problems come up in completing any job all the way. There is a history of carb problems, I think starting with when they first touched the car (and crashed it during a compresson test two weeks after I bought it)..this has been a tough road..
My next step is to change the oil, which was not done along the way...
I'd appreciate your input. I wish this was a simple whats the deal with the lifter but the sequnnce of events and contiions complicate it.
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