C3-1971: Engine Rebuild or Valve Job?

[Greg F.]

I had my local mechanic replacing my valve seals this week on my small block 71 (completely original). He gets to the last valve and notices the valve has a little damage at the top. He called it "Mushroomed". I went to look at it and it has a little nick and edge is pushed out a bit. I never noticed anything while driving...no ticking....nothing. I told him to complete the job and I have a decision to make.

The engine has 63/K original miles. Doesn't burn any oil. I wanted to replace the valve seals because it was blowing white/blue smoke during initial start up and noticed the plugs were a little fouled. The motor pulls nice and smooth. I don't drive it hard.

Has anyone had this type of issue?

Since the motor seems strong, should I plan to do a valve job or remove the entire motor to rebuild it? My funds are bit tight, so thats my biggest concern.

Approximately, how much would a complete rebuild versus a valve job cost?

Any suggestions are great.

Thanks.

[Tom L.]

Re: C3-1971: Engine Rebuild or Valve Job?

I don't know that you need to do anything. It sounds like you may have had an oiling problem there at one time. What did the rocker arm look like where it contacts the valve stem? Once the valves are adjusted after replacing the seals, the valve will open 100%, even if some metal was lost from the end of the stem. If there was only minimal metal loss and you have verified that oil is now getting to the rocker arm, I wouldn't mess with it. The question is do you have slight or serious deformation to the valve stem? Did you take pictures while it was apart?

[Greg F.]

Re: C3-1971: Engine Rebuild or Valve Job?

Tom,

Thanks for you reply. I tried to take a picture with my digital but you can't seen anything...unfortunately. It is slight metal loss and the rocker arm is fine. The mechanics first guess was the engine may have had low oil at some point in its life and that could have caused it. I'm not sure of other reasons, so volunteer them if you know!!

Since I've had the car, I haven't had any oil burning/loss. The motor has ran great. What are some future symptoms I can expect if that valve stem starts to get worse?

Thanks again,
Greg

[Joe L.]

Re: C3-1971: Engine Rebuild or Valve Job?

Tom,

Thanks for you reply. I tried to take a picture with my digital but you can't seen anything...unfortunately. It is slight metal loss and the rocker arm is fine. The mechanics first guess was the engine may have had low oil at some point in its life and that could have caused it. I'm not sure of other reasons, so volunteer them if you know!!

Since I've had the car, I haven't had any oil burning/loss. The motor has ran great. What are some future symptoms I can expect if that valve stem starts to get worse?

Thanks again,
Greg

Greg-----


I don't see a loss of oil pressure causing this, especially if the rocker arm shows no damage. More likely, it may have been due to a defect in the valve that existed from manufacture. It's hard to say without actually seeing what you're talking about.

Actually, unless it's a lot worse than I'm picturing in my mind, I don't think it will cause any problem, especially if the car is limited use. I would just check the sound of the engine by listening at the valve cover every now-and-then to see if you notice any sign of a loosening rocker adjustment. Most likely you'll hear a distinct "clicking" before any serious problem develops.

[Tom L.]

Re: C3-1971: Engine Rebuild or Valve Job?

I agree with Joe. It don't think low oil pressure would damage an isolated valve stem without harming anything else. I was thinking more along the lines of gunk in your push rod.
Regarding additional causes, I've also seen abnormal valve stem wear with very worn guides because the valve stem won't line up square with the rocker arm under load. Did your mechanic check the guides while the springs were off?

[Larry L.]

Re: C3-1971: Engine Rebuild or Valve Job?

I had the blue smoke problem expecially after a short shut down after pulling of the highway. The engine has 41K miles on a 66 350 / 327. I was reading about oil and missing adatives that I thought I needed. changed to Rotella and smoke problem disapeared. It the valve damage does not come in contact with the rocker arm surface - you don't care. I have seen some good mechanics carefull grind the top of the valve stem to ture them up.

[Joe L.]

Re: C3-1971: Engine Rebuild or Valve Job?

I had the blue smoke problem expecially after a short shut down after pulling of the highway. The engine has 41K miles on a 66 350 / 327. I was reading about oil and missing adatives that I thought I needed. changed to Rotella and smoke problem disapeared. It the valve damage does not come in contact with the rocker arm surface - you don't care. I have seen some good mechanics carefull grind the top of the valve stem to ture them up.

Larry-----


Grinding the top of valve stems is a common "reconditioning" practice. I don't like it, though. If a valve needs to have the top of the stem "trued", I'd always opt to replace the valve.