Deep scratch- GM 454/438hp roller cam

[Machtuck]

Pulled this GM billet 454/438hp crate engine cam out and was aghast at this deep scratch on one of its lobes. This is a mild cam: 211/230 .510/.540 112lsa. Running Howards 98611 single springs with damper. They are all set up around 1.9 heights which puts it about 140lbs on the seat and 340lbs at full lift. Cam is in a 9:1 402. Lifters are Howard’s Max Effort roller lifters and all look and operate perfectly. They are the full wheel type. It looks as if the lifter body may have contacted the lobe but again, no damage whatsoever to the associated lifter. DISCLAIMER- I cannot confirm nor deny that it may have spun a little high once or twice. No strange noises and this engine ran excellent with this cam. In fact, it’s a perfect cam for 4000# car, small converter, good exhaust and 3:42 gear. Pulls real hard with a small lope at idle and at 15 degrees idle and 36 total with stage two quadrajet and 1 3/4” headers. I calculated 15 mpg. Would like to use it again. Emory cloth ok?
Any ideas are greatly appreciated.

[CamKing]

That's from the edge of the roller wheel.
It looks like, either the cam is screwed up, and has taper on that lobe, or the lifter bore is not perpendicular to the cam.

[Machtuck]

Thanks Mike. I never thought about the cam having a slight taper or imperfection. The block has had other cams with no apparent issues. Hoping that would eliminate the lifter bore not being aligned.

[Greenlight]

Is the mark on the opening side or closing side of the lobe?

Approximately how deep is the scratch/mark?

Do you know how much lifter travel the Howard's lifters have?

I ran across a similar problem on some air boat engines (540 cid BBC, 6000 max. RPM).

[Machtuck]

I’m currently don’t have the cam to see but i think it was the closing side. The scratch is fairly deep. Very noticeable with the thumb nail. Don’t know the lifter travel but used these lifters on another more aggressive cam for a few years and no issues. Is there a way to check to see if there’s lobe taper? I would like to re-install this cam if at all possible. Thanks again for the replies.

[Lizardracing]

I’m currently don’t have the cam to see but i think it was the closing side. The scratch is fairly deep. Very noticeable with the thumb nail. Don’t know the lifter travel but used these lifters on another more aggressive cam for a few years and no issues. Is there a way to check to see if there’s lobe taper? I would like to re-install this cam if at all possible. Thanks again for the replies.

A .0001 mic would be good enough.

[Machtuck]

Ok. Thank you

[Greenlight]

I’m currently don’t have the cam to see but i think it was the closing side. The scratch is fairly deep. Very noticeable with the thumb nail. Don’t know the lifter travel but used these lifters on another more aggressive cam for a few years and no issues. Is there a way to check to see if there’s lobe taper? I would like to re-install this cam if at all possible. Thanks again for the replies.

I had some airboat engines (maybe 4 or 5) that developed a similar problem. These engines may be run at 5500 RPMs for 30 minutes. The lifters had about 0.200" travel. We replaced the lifters with low travel lifters ( 0.050" ???) and the problem went away. I suspect that "valve float" was occurring.

[Machtuck]

That’s interesting. I’m going to mic the lobes and see if there is some taper. If no taper, i’ll probably install the lunati 121 springs which will have more seat and open pressure. Also, they are a dual spring.

[Machtuck]

I’ll check the lifter travel. Thanks for the reply

[MadBill]

I’m currently don’t have the cam to see but i think it was the closing side. The scratch is fairly deep. Very noticeable with the thumb nail. Don’t know the lifter travel but used these lifters on another more aggressive cam for a few years and no issues. Is there a way to check to see if there’s lobe taper? I would like to re-install this cam if at all possible. Thanks again for the replies.

That seems counterintuitive; there's normally higher contact forces on the opening side, so at the least it should also show wear....

[Adger Smith]

I have seen a few cams with roller edge tracks like that.
As stated earlier, taper on the lobe or lifter bore out of alignment or too much cam end play is where I start looking for the cause.

[cknight]

This also occurs when the guidebar on that pair if lifters does not have the arrow pointing up, causing the wheels not to track squarely on the lobe.

[Machtuck]

Good stuff. I’m still on a trip and will check to see if it was opening or closing side.




These are the springs.


http://www.competitionproducts.com/Howa ... /HRC98611/

Don’t know if this hyperlink works or not.

145lb at 1.88 and 350lb at 1.25” max open. Don’t know the rate but I’m wondering if even the small nature of this cam would be too much for these single springs.
They are advertised for solid flat and hyd roller.

Exh lift is .540. Maybe open pressure not adequate especially at high rev.

How do i check lifter alignment?

I’ll take a look at the horizontal bar arrows too.

Thanks again for your replies.

[ProPower engines]

Pulled this GM billet 454/438hp crate engine cam out and was aghast at this deep scratch on one of its lobes. This is a mild cam: 211/230 .510/.540 112lsa. Running Howards 98611 single springs with damper. They are all set up around 1.9 heights which puts it about 140lbs on the seat and 340lbs at full lift. Cam is in a 9:1 402. Lifters are Howard’s Max Effort roller lifters and all look and operate perfectly. They are the full wheel type. It looks as if the lifter body may have contacted the lobe but again, no damage whatsoever to the associated lifter. DISCLAIMER- I cannot confirm nor deny that it may have spun a little high once or twice. No strange noises and this engine ran excellent with this cam. In fact, it’s a perfect cam for 4000# car, small converter, good exhaust and 3:42 gear. Pulls real hard with a small lope at idle and at 15 degrees idle and 36 total with stage two quadrajet and 1 3/4” headers. I calculated 15 mpg. Would like to use it again. Emory cloth ok?
Any ideas are greatly appreciated.

I have seen that issue as well with GM crate stuff guys run in boats for a short time then find they need more cam.
As mentioned the lifter alignment of the lifter bore may not be the issue but I have seen the axle for the roller off a few thou making the edge of the roller dig into the lobe.

Check the roller wheels for alignment as well.
The other thing if you want to reuse the cam send it to the local re-grinder. The GM crate profiles are some thing they can match up easily. For less then $100 to repair its worth the time to send it out.
I have done this to 5-6 cams in the last year or so and had no adverse affects to push rod length and found that they would be about.005" difference which is nothing for what your wanting.
But I did find as Mike suggested 1-2 cams did have a slight taper in the lobe which was corrected during the re-profiling of the cam but they had several lobes that needed attention.