Solid cam damage diagnosis help

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PRH said:
Question......

In the first two pics...... is the cam oriented the same way between the two, or was it flipped end for end?
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I added a pic of the whole cam. Engine is a 340. What would cause the lifter to ride the edge like that?
 
Looks like the cam was riding too for forward on the bore.
 
Well, the lobe taper is not staggered, so that’s not correct.

If you know someone with a lathe....... mount the cam in the lathe, preferably on centers.
Indicate across a couple of bearing journals to make sure the cam is parallel to the centers.
You’d like to see solidly less than .0005 difference front to rear of the journal.

Now move to a cam lobe on the base circle.
Indicate the taper front to rear of the lobe.
Stock stuff is usually under .001” taper.

“Most” of the name brand performance stuff is .0015-.0020.

See where that is before going any further.
If the taper is way high(which I suspect it might be)..... get a new cam and move on.

Since whoever did that one seems to not know about the staggered taper for SBM....... I’d probably get the replacement somewhere else.
 
Last edited:
PRH said:
Well, the lobe taper is not staggered, so that’s not correct.

If you someone with a lathe....... mount the cam in the lathe, preferably on centers.
Indicate across a couple of bearing journals to make sure the cam is parallel to the centers.
You’d like to see solidly less than .0005 difference front to rear of the journal.

Now move to a cam lobe on the base circle.
Indicate the taper front to rear of the lobe.
Stock stuff is usually under .001” taper.

“Most” of the name brand performance stuff is .0015-.0020.

See where that is before going any further.
If the taper is way high(which I suspect it might be...... get a new cam and move on.

Since whoever did that one seems to not know about the staggered taper for SBM....... I’d probably get the replacement somewhere else.
Click to expand...
The cam is a Hughes Engines cam. I went with them because it seems theyre consistently the better product, more specialized in Mopar engines. I don't have access to anyone with a lathe locally. No machine shops any more around here.
 
Lil Demon said:
I am with you on your opinion, that is what I believe happened. engine start up was attempted at least 12 times with EFI, probably went another 2 weeks until the carb was installed and fired up. Being the situation i'm in I am considering just taking out the inner spring for break in either way. I would just hate to have to open it up once more.
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It was killed because it didn’t start. Sitting forever didn’t help it either.

You just can’t screw around and not get them running. Why it went 12 tries I can’t say. But after the 2nd or 3rd try they should have stopped and figured it out.
 
FWIW, I also noticed my timing chain seems to have stretched. I don't remember it having as much slop as it does now.
 
Looks like the cam was riding too for forward on the bore.
Click to expand...

I suppose there could be some oddball issue with how the core was made up near the front.......but
Since the SBM uses a thrust plate to locate the cam...... I don’t know how you could have the cam positioned too far forward in the block.
But it’s probably worth looking that situation over.
Just slide the cam back in the block, put on the thrust plate and gear...... see how the lobes look when viewed thru the lifter bores.
 
yellow rose said:
It was killed because it didn’t start. Sitting forever didn’t help it either.

You just can’t screw around and not get them running. Why it went 12 tries I can’t say. But after the 2nd or 3rd try they should have stopped and figured it out.
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I agree, I went back and forth with the EFI tech support. Then told them I was done pissing around with their product and threw the carburetor on it. I knew that was a factor that's why I was very clear about relaying the information.
 
PRH said:
I suppose there could be some oddball issue with how the core was made up near the front.......but
Since the SBM uses a thrust plate to locate the cam...... I don’t know how you could have the cam positioned too far forward in the block.
But it’s probably worth looking that situation over.
Just slide the cam back in the block, put on the thrust plate and gear...... see how the lobes look when viewed thru the lifter bores.
Click to expand...


The cam gear sets the cam thrust and position. If it has too much thrust then you machine off the back of the cam gear.
 
This particular issue has nothing to do with the actual start up and break in imo.

It’s not “worn” from lack of lube.
It’s pieces broken away.
 
Lil Demon said:
The cam is a Hughes Engines cam. I went with them because it seems theyre consistently the better product, more specialized in Mopar engines. I don't have access to anyone with a lathe locally. No machine shops any more around here.
Click to expand...

I would send the cam back to Hughes and see what they say.
 
yellow rose said:
The cam gear sets the cam thrust and position. If it has too much thrust then you machine off the back of the cam gear.
Click to expand...

Which doesn’t really explain why the cam doesn’t appear to have the staggered taper.

Again...... just slide the cam back in with the thrust plate and gear and see what you have.
5mins tops.
 
PRH said:
This particular issue has nothing to do with the actual start up and break in imo.

It’s not “worn” from lack of lube.
It’s pieces broken away.
Click to expand...
As stated before I already re-ordered the same camshaft. I will definitely reinstall the cam and see how it centers with the lifter bores as suggested. Do you think it was just a fluke grind? Or do you suggest another more trusted manufacturer? I was really hoping to stick with this grind.
 
brian6pac said:
I would send the cam back to Hughes and see what they say.
Click to expand...

Or to someone else for an unbiased opinion.

It “looks” like it has loads of taper from the pics.
If in fact it does, it’s a defective part imo.

If it doesn’t, and it does actually have the staggered lobe taper like it’s supposed to...... then you have another issue.
 
Lil Demon said:
The cam is a Hughes Engines cam. I went with them because it seems theyre consistently the better product, more specialized in Mopar engines. I don't have access to anyone with a lathe locally. No machine shops any more around here.
Click to expand...
Send the cam to Hughes for inspection.
Who knows maybe you will get a free replacement.
 
Lil Demon said:
As stated before I already re-ordered the same camshaft. I will definitely reinstall the cam and see how it centers with the lifter bores as suggested. Do you think it was just a fluke grind? Or do you suggest another more trusted manufacturer? I was really hoping to stick with this grind.
Click to expand...
Are you going to reuse the EDM lifters?
Make sure you check the oil pump for trash.
 
You could send it to me and I could check it for taper....... but you’d be paying freight just so you knew that was it...... or wasn’t it.

If the taper is as bad as it “looks” in the pics, you could probably pick it up with a dial caliper.
 
I wasn't looking for a freebie. I want to learn from the situation. I had already ordered the replacement cam. I just called once again and spoke to Tim. He did glance at the pictures and was referring the situation to their cam tech. I was very upfront with him this morning of the situation. Like I said I want to learn and correct the situation. I hope they are equally forthcoming if it's determined it a bad grind. I just want to know. I am really going to try and locate a lathe to check the taper.
 
PRH said:
You could send it to me and I could check it for taper....... but you’d be paying freight just so you knew that was it...... or wasn’t it.

If the taper is as bad as it “looks” in the pics, you could probably pick it up with a dial caliper.
Click to expand...
Where exactly would I make the comparative measurements?
 
Lil Demon said:
Where exactly would I make the comparative measurements?
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Measure one side of the lobe verses the other.

So clear something up for me. You tried to start it 12 times. During those 12 times, how long was it cranked on?

IDK who ground it, or how much taper is has, or doesn’t have, or if you used a dual spring or pulled the inners (waste of time...even with 80 pounds on the seat if you crank on it long enough it will go flat) or used a low ratio rocker, when you crank on the and they don’t run, they die.
 
Lil Demon said:
I wasn't looking for a freebie. I want to learn from the situation. I had already ordered the replacement cam. I just called once again and spoke to Tim. He did glance at the pictures and was referring the situation to their cam tech. I was very upfront with him this morning of the situation. Like I said I want to learn and correct the situation. I hope they are equally forthcoming if it's determined it a bad grind. I just want to know. I am really going to try and locate a lathe to check the taper.
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If you're honest with Tim, he will bend over backwards to help you. He does stand behind his products and understands sometimes parts fail.
Good Luck
 
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