Mike,
Not to be the grim reaper here but your description almost exactly matches
what I experienced when one of my valve springs broke. Unfortuantley (for
me) it was the fact that idle seemed unaffected that led me to continue
driving a couple hundred yards to the next intersection. The damage this
did to my engine has been well documented in previous posts.
I sincerely hope that Dick Taylor is right and it was only a backfire. But
if I were you, I'd take the time to pull off the valve cover and take a
look. It'll only take five minutes and you might save your engine.
An ounce of prevention...
John
On 5/28/02 6:02 PM, "YeOldEd@aol.com" <YeOldEd@aol.com> wrote:
> Just when I thought everything in the garage was lovely, up jumped the devil!
>
> Such a great day so I fired up my 72 for a run. Rebuilt engine, 100 miles,
> all standard as far as I know. She started immediately, then, after about ten
> seconds, there was a moderately loud "crack", fairly high frequency,
> apparently from the top rather than the bottom. (I hope.) Surprisingly, idle
> seemed to be unaffected. I didn't rev the engine. No other unusual noises,
> but a small amount of black smoke from the left exhaust where there was none
> before.
>
> I,m guessing valve, valve spring, push rod, rocker, but puzzled at how quiet
> she was after the initial noise.
>
> Any ideas before I start to tear apart the wrong thing?
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