Lifters NOT flat

I could be off-base here, but I believe most automotive cams have a very, very slight taper in the cam lobes, and the lifters are ground to a 60" radius... or maybe it was a 60" circle. Bottom line is that I believe the goal is to match the very tiny taper in the lobe close to the radius on the lifter, and this causes the lifter to rotate a tiny bit with each valve lift. This prevents the lifter from getting worn from sitting in the same orientation all the time.

PM
 
Your are correct. That’s how they get the lifter to spin on the lobe and not just naw away at the same location day in and day out.
 
...all of which makes me weary about running the lightweight lifters that are flat. I'm going to put the short block together and see if the cam still manages to spin them. (I could see the stockers spinning when I looked down the "lifter valley") But if it doesn't I may just have 4) 18.19-18.39 gram lifters for sale. Hell if they don't spin they will probably be underweight in no time, and the cam will likely have less lift fairly quick.
 
...all of which makes me weary about running the lightweight lifters that are flat.
If the lifter centerline is offset to the lobe width centerline, the lifter will rotate
even if it is flat. The wear pattern on the lifter will be wider than the cam
lobe if it's offset.
 
If the lifter centerline is offset to the lobe width centerline, the lifter will rotate
even if it is flat. The wear pattern on the lifter will be wider than the cam
lobe if it's offset.
Yeah that's what I am expecting. I would expect even if the blueprint calls for perfectly centered, given the country of origin, they are likely not.

I am worried that if the dome of the lifter does not match the potential taper of the cam it will wear the cam out on one side of the lobe tho.
 
All good points on the rotation of the lifter .
Cam face or offset both would affect it .
I have not paid much attention to it but the few i have had out didn't appear too have spun . as the wear pattern was mostly square or rectangular .
Honestly doubt its much of an issue . Isn't the cam hardend also .
 
I just put together 2 short blocks with flat lifters, they move back and forth when the crank is spun but I wouldn't say they spin. Time will tell how they and the cam wear I guess. If I flatten off cam lobes or eat lifters it's not like I'm out over $75, ya just gotta worry what any shavings are doing to the rotating assembly.

I'm banking on it not being much if an issue either way, it's just not race season yet so I have time to think about such things while I try and stay warm.

The standard weight lifters that were previously ran show a very nice circular wear pattern because they rotated well.

I will be watching the max lift in the cam very closely every week, like usual. If I see it keeping getting less and less I'll know to buy a cam and go back to standard weight lifters.
 
The need for the lifters to spin is more prevalent with high spring pressures.
I do not think cam wear will ever be an issue with stock spring pressures.

Cams are ground with a taper on the lobes. This also helps control cam walk, and the associated timing changes, in multiple cylinder engines.
Briggs engines use straight cut gears, so timing does not change, if the cam walks back and forth in the block.
Honda and the clones use bevel cut gears which can change valve event timing with cam walk.

Think differences with loose, or tight fitting cam gears.
 
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