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496 BB with failed cam lobe

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Mr. Fixit

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Discussion starter · #1 ·
Hi all,

I recently bought a 68 with a BBC. I drove it less than 15 miles and heard a strange sound which led me to evaluating that there was a cam lobe failure on one lobe. I can certainly provide the engine specifics as I know them, but my question is a general one.

For anyone that has experience in this area, would you recommend a complete engine tear down, or is it possible to drop the pan, clean the screen, oil pump and pan and then rebuild the valve train? I was told by the seller that the engine had 2500 miles on it, and looking at the block with the intake removed, the top side of the heads and the underside of the valve covers, it looks so clean you could eat off of it.

Thank you.
 
#2 ·
Hate to say it, but it's a do-over. A wiped lobe simply leaves too much shrapnel in the crankcase. If it were an older engine, I'd might try a cam/lifter swap followed by 2-3 quick oil/filter changes.

But it sounds like you have too many new parts take the chance.

The good news is, you're only looking (hopefully) at a tear down, inspection, and clean-up, which won't kill your wallet if everything checks out.

Also, now's a good time to consider a roller cam.

Good luck,..I feel your pain,..I've been there.
 
Discussion starter · #3 ·
Straight-line-69 said:
Hate to say it, but it's a do-over. A wiped lobe simply leaves too much shrapnel in the crankcase. If it were an older engine, I'd might try a cam/lifter swap followed by 2-3 quick oil/filter changes.

But it sounds like you have too many new parts take the chance.

The good news is, you're only looking (hopefully) at a tear down, inspection, and clean-up, which won't kill your wallet if everything checks out.

Also, now's a good time to consider a roller cam.

Good luck,..I feel your pain,..I've been there.
Click to expand...
Thanks for the input, I kinda figured that it would be the best approach. I have worked on and build many cars, but never a Camaro. How the heck does the engine come out. It looks like the entire front of the car needs to be removed. It looks like it was put in with a shoe horn..lol
 
#4 ·
Do a search on here for engine removal, lifting,etc. Its not as bad as you'd think just takes a little time,patience, and persistence. Get as educated as possible before taking the leap and you'll be fine.
 
Discussion starter · #7 ·
PA Camaro Guy said:
You said the motor had 2500 miles-- did the cam have 2500 or 15? I understand this failure happens pretty fast, would be seen before 2500.
Click to expand...
I bought the car less than 4 weeks ago. The seller told me that the engine had less than 2500 miles on it. Once I got it home, i drove it less than 15 miles and things went south.
 
#8 ·
Are you sure it's a cam lobe? That should have showed way before now, when we did my buddy's Mach 1, and learned the hard way about new oils not having additives (heck, it's been over 20 years since we rebuilt an engine :eek:), the lobe wiped in the first test drive.
Lesson learned.
Unless someone over tightended the valve recentely, the lobe should have worn way before 2500 miles?
 
Discussion starter · #9 · (Edited)
PhantomRider said:
Are you sure it's a cam lobe? That should have showed way before now, when we did my buddy's Mach 1, and learned the hard way about new oils not having additives (heck, it's been over 20 years since we rebuilt an engine :eek:), the lobe wiped in the first test drive.
Lesson learned.
Unless someone over tightended the valve recentely, the lobe should have worn way before 2500 miles?
Click to expand...
Good point, and why just one lobe? I spoke with comp cams tech and all they had to offer was the lacking oil additives that we all know about. Below is a pic of the injury.:mad:

Thanks for your input
 
#10 ·
My Buddies 396 Camaro went flat on a lobe after driving the car for a couple years. Probably 5K Miles on it.

I put a new cam and lifters in it for him. There was no metal in the valley or anywhere in the heads. Visual and magnet checked.

Did the cam and new oil and filter (the right oil) ran it for 20 min break in. Changed oil. Drove it 100 miles and changed oil again.

No issues in the 2 1/2 years since.
 
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Discussion starter · #13 ·
Vega$69 said:
My Buddies 396 Camaro went flat on a lobe after driving the car for a couple years. Probably 5K Miles on it.

I put a new cam and lifters in it for him. There was no metal in the valley or anywhere in the heads. Visual and magnet checked.

Did the cam and new oil and filter (the right oil) ran it for 20 min break in. Changed oil. Drove it 100 miles and changed oil again.

No issues in the 2 1/2 years since.
Click to expand...
I wish that I could feel comfortable just doing that and hoping for the best. I don't want to risk trashing the motor for a a days effort. :noway:
 
#14 ·
Mr. Fixit said:
I will be checking everything when it is fully disassembled.

Thank you..
Click to expand...
We only had one down too. The lifter was 1/4" shorter then the rest when we pulled it out

We traced the issue to what we believe was a bad batch of lifters that comp sold for a while.

A good check is to stand the lifters on a piece of glass. They should be slightly round on the bottom and will rock a little when standing on the glass.

Image


Image
 
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Discussion starter · #15 ·
Vega$69 said:
We only had one down too. The lifter was 1/4" shorter then the rest when we pulled it out

We traced the issue to what we believe was a bad batch of lifters that comp sold for a while.

A good check is to stand the lifters on a piece of glass. They should be slightly round on the bottom and will rock a little when standing on the glass.

Image


Image
Click to expand...
Gee that looks familiar. I will be going with a roller cam and lifters this go around. No pun intended.
 
#16 ·
Mr. Fixit said:
I wish that I could feel comfortable just doing that and hoping for the best. I don't want to risk trashing the motor for a a days effort. :noway:
Click to expand...
My Thoughts.

The cam/lifter metal goes straight to the bottom of the pan. It then would go through the filter before pumped back through the motor.

After the 20 minute run it. We drained the oil and cut the filter open. Ran a strong magnet between the folds of the filter. Nada.

We did flush out the bottom of motor pretty good with the intake off and the drain plug on the pan removed.

If you're a extremely paranoid on the new cam and lifter you can use break in springs.
 
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#17 ·
John, that's interesting, did you get confirmation that Comp Cams had a bad batch of lifters?
That's exactly what happend to my buddy's Mach 1, and it was Comp Cams, bout 3 years ago or so.
Only one lifter was wore down about the same as you mentioned. He called Comp and they said it was the oil we used and would give no help. Figured since the lifters was shot and the cam probably too, we just put one the stock lifters back in and the car ran ok, he drove it that way a couple years and we just repulled the motor this summer and rebuilt it with new cam and lifters, but that was because one his wrist pins started walking and wore a grove in his cylinder (different one than the lobe was worn on.) Since it was number matching motor, he had it sleeved and e put it back together, going to drop it back in this spring. The cam was wiped a bit, but not as bad as the lifter was.
 
Discussion starter · #18 ·
PhantomRider said:
John, that's interesting, did you get confirmation that Comp Cams had a bad batch of lifters?
That's exactly what happend to my buddy's Mach 1, and it was Comp Cams, bout 3 years ago or so.
Only one lifter was wore down about the same as you mentioned. He called Comp and they said it was the oil we used and would give no help. Figured since the lifters was shot and the cam probably too, we just put one the stock lifters back in and the car ran ok, he drove it that way a couple years and we just repulled the motor this summer and rebuilt it with new cam and lifters, but that was because one his wrist pins started walking and wore a grove in his cylinder (different one than the lobe was worn on.) Since it was number matching motor, he had it sleeved and e put it back together, going to drop it back in this spring. The cam was wiped a bit, but not as bad as the lifter was.
Click to expand...
When I spoke with them, the tech was quick to say that it was the oil and as you mentioned offered no $$$ help. They offered a new cam to me at the jobber price which was nice, but was still more that published prices from some online sources that we all use.
 
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Mr. Fixit
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