flat cam lobe

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Ivoryk3ys78

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Hi there. I have a 318 in my 72 Duster and the other day while trying out a different carb we made it just a little ways down the road before we heard the unpleasant noise.

If the engine was running it would blow through the carburetor. We initially were thinkign bent valve.

We discovered that one of the roller rockers was not moving at all. This is first exhaust valve from the front passenger side of the car. We thought it was probably the internals of the hydraulic lifter.

When we got the intake off we discovered that both the lifter and the lobe are shot, both the lifter and the cam being worn down.

This is not a new cam. It is an old 484 that has been run for years. The engine has X heads on it with double valve springs.

I have since purchased a Comp Cams XE284H and lunati lifters but obviously don't want to put them in and have this happen again.

The only thing that I can think of is oiling. I was thinking of getting that lifter and another out and priming with a drill and trying to see how well its oiling. We obviously got to do some cleaning to get these fine shavings out of there and clean everything up. I am wondering what would be a good solution to use for that that would be a safe option.

Any ideas would be appreciated.

Thanks a lot
 

I agree, Rotella and Valvoline VR-1 are high zinc. When I had a lobe go flat on my 440, (solid lifter) I caught it pretty quick, and it had only worn down about .100" on the lobe. I suppose a hydraulic cam will keep adjusting as the lobe wears, and then you don't notice it until the lifter plunger is all the way up, and the lobe is mostly gone. So to clean it good, I pulled the oil pan, and cleaned it, but didn't find much. I put in a solid roller cam, new oil pump, and changed the oil 3 times. Ran it about 5 minutes the first time. Changed it and filter, ran for 5 or 10 min, changed oil only. Then drove it awhile, then changed oil again. Never could find much debris, except a few fine particles the first time. That 440 6 pack motor ran great after that. Really depends on how bad the first oil looks. Some guys pull the motor, then disassemble and clean it. My short cut worked for me. Wasn't using a high zinc oil at that time.
 
Check the adjuster didnt back off and let it all clap itself to death.
Need good oil, but mostly... you need good springs 1st.

See if you didnt have piston valve interference, look for marks.
 
Sine the passenger side lifter gallery provides the oiling to everything, it seems doubtful that it is an oiling issue, unless there is something large plugging the gallery between cylinders 2 and 4. IN that case, the #1 main & #1 rod would be effected as well as the whole left side lifters.

BTW, the PPM of ZDDP in Roltella has dropped some; it is now in the 1100-1200 PPM range. It's not as low as the newer CI oils which are down around the 800-900 PPM levels, but it's not as high as Rotella used to be.
 
I had a lobe go flat with a MP 484 cam years ago. It was in the car for a couple years before it went. I read somewhere that MP had problems with their cams. Put in a new Comp cam, Bought a bottle of Chevy break in lube, filled with Rotella, primed the oil pump, and kept changing the oil, and filter. That was over 15 years ago. that engine still runs good. Make sure your engine is ready to start right away. I like the idea of cleaning out the oil pan, new pump. I would spray the inside of the engine down with Brake Clean. Check bearings while the pan is off. I have also used Comp breakin oil to fill the engine with. no issues.
 
There are many reasons why a cam lobe goes flat . Lack of lubrication is one . Defective roller or cam . Excessive idling (or low speed operation) . Wrong oil . Stuck valve or rocker . Whatever the reason , remember , you have metal debris throughout your motor and you can't flush it out without scoring your cam/main/rod bearings .
 
Hi Furyus, what do they call that Chevy break in lube? Back in the 70s, I used Engine Oil Supplement, or EOS, available at the Chevy Parts counter. Worked great! Now they don't seem to know what I'm talking about. I used it to break in a couple of Racer Brown mushroom lifter cams with .690 lift, and no problems. Do they still Call it EOS? Or maybe the Comp Cams break in lube is similar? Thanks
 
Now that you mention it, I think they discontinued it, since they no longer use flat tappet cams. I think that's why I went with the Comp break in oil. I filled the crank case with it. No issues.
 
That's good oil. Why double valve springs? That cam doesn't need them, regardless of what Mopar Performance might recommend.
 
How thoroughly you clean the engine is your call, but aside from that......

I’d want to verify the spring specs are suitable for the new cam, and are set up to provide enough clearance to coil bind at full lift, as well as verifying the retainer to seal clearance.

Then, verify the new cam has proper lifter rotation on that problem hole(well, all holes actually).

If it all checks out....... put it back together, do your break in...... you should be fine.
 
It's a roller cam yes?
I don't believe rollers need the high zink oils.....
Or am I missing something?

Edit....reread.....roller rockers...nevermind...



Jeff
 
MrJLR said:
It's a roller cam yes?
I don't believe rollers need the high zink oils.....
Or am I missing something?

Edit....reread.....roller rockers...nevermind...



Jeff
Click to expand...

No you are not missing anything, as the problem is just people not reading enough of the info to realize their answer doesn't apply is all.:D

In my opinion the last sentence of post #8 is about the most important answer of the whole thread.

If that motor ate a lobe and part of a roller lifter for desert it's full of metal and money spent without a complete disassembly and inspection is wasted money.
All that crap falls right down on the cam, crank and rods, and works it's way right into all those bearings.

The lobe circled imbedded metal in every bearing in the entire engine and even scored the #7&8 cylinders a little from the crank slinging the particles up into them.

lobecircled.jpg


SANY0010.JPG
 
Last edited:
RustyRatRod said:
His camshaft is not a roller. It's a MP 282/484.
Click to expand...

Doh!
(Somebody) didn't read well enough.:D
"Roller rockers", duh.

Point is still the same though, that motor has metal powder imbedded in the bearings now.
When I did the one I pictured above I hoped the oil filter caught it, but noooo. (remember the pump bypass)
It trashed every bearing in the back of the engine since it was the #8 intake valve lobe.
From #4 forward wasn't near as bad but you could still see bits imbedded in the bearing material.
 
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