Truth about roller cams.... BEFORE you make the switch......
I was just about to say the same thing. Tappet vs roller shouldn't really effect the material properties of the cam gear. The core could care less what kind of lobe is ground onto it. The wear of the gear is determined by the heat treatment and more so the metal of the cam (different alloys have different heat transfer, different hardness, different elasticity characteristics). I have a cast core roller cam in my 360.
Example:
These are two, different core billet sbc camshafts I used on some lifter durability testing on a SpinTron (engine with no rotating assembly, uses an electric motor to drive valve train. Dry sump w/o distributor, so no wear on the gear, but shows how different cores have different materials properties). Same lobes, lifters springs, rpm cycles, etc. Started with a higher-quality core, usually specced for use in high stress applications. Top of the line billet core. Long story short, a piece failed and a cam journal was starved of oil. Went ahead and had a new cam made, but those cores were out of stock for a few weeks so the next level down of a core was used. At around half of the time we had on the original core, the new cam snapped.
So it's not tappet vs roller, but the characteristics of the core. Sort of like cast pistons vs hyperutectic or forged pistons. Oil pumps play a pretty big role in gear wear as well- a high volume pump is going to put more load on the gears than a stock pump would. Engine horsepower too- just idling around vs a 5,000 rpm jump off the line racing.
For most applications, using whatever the cam grinder recommends should suffice. Billets needs bronze, and you shouldn't cheap out on using a used gear with a new cam. Different cam grinders use different cores on different cams, and you can have different cores on cams with the same exact lobes. You can have both tappet and roller lobes ground on both cast and billet cores. Different cores within the same cam grinding company.
If you haven't seen how it's done, I recommend if you're ever in Memphis to take a tour of Comp Cams. You can see all of the different stocked cam cores, how cores are ground, how are cnc process works, the mse finishing process can be done. I'm sure every other cam company is similar, but it's more than tappet cores are cast, roller cores are billet, this gear for tappet, that for roller.
I was just about to say the same thing. Tappet vs roller shouldn't really effect the material properties of the cam gear. The core could care less what kind of lobe is ground onto it. The wear of the gear is determined by the heat treatment and more so the metal of the cam (different alloys have different heat transfer, different hardness, different elasticity characteristics). I have a cast core roller cam in my 360.
Example:
These are two, different core billet sbc camshafts I used on some lifter durability testing on a SpinTron (engine with no rotating assembly, uses an electric motor to drive valve train. Dry sump w/o distributor, so no wear on the gear, but shows how different cores have different materials properties). Same lobes, lifters springs, rpm cycles, etc. Started with a higher-quality core, usually specced for use in high stress applications. Top of the line billet core. Long story short, a piece failed and a cam journal was starved of oil. Went ahead and had a new cam made, but those cores were out of stock for a few weeks so the next level down of a core was used. At around half of the time we had on the original core, the new cam snapped.
So it's not tappet vs roller, but the characteristics of the core. Sort of like cast pistons vs hyperutectic or forged pistons. Oil pumps play a pretty big role in gear wear as well- a high volume pump is going to put more load on the gears than a stock pump would. Engine horsepower too- just idling around vs a 5,000 rpm jump off the line racing.
For most applications, using whatever the cam grinder recommends should suffice. Billets needs bronze, and you shouldn't cheap out on using a used gear with a new cam. Different cam grinders use different cores on different cams, and you can have different cores on cams with the same exact lobes. You can have both tappet and roller lobes ground on both cast and billet cores. Different cores within the same cam grinding company.
If you haven't seen how it's done, I recommend if you're ever in Memphis to take a tour of Comp Cams. You can see all of the different stocked cam cores, how cores are ground, how are cnc process works, the mse finishing process can be done. I'm sure every other cam company is similar, but it's more than tappet cores are cast, roller cores are billet, this gear for tappet, that for roller.