[NovaFan63]

I have the zz4 camshaft with hydraulic rollers. I purchased a Summit HEI distributor pn SUM-850001R. I read that a melonized cam gear drive is required for steel roller camshafts. What the heck does that mean? Do I need to purchase a different ditributor gear for my Summit distributor? What does "melonized" mean? What happens if I run it with the "hardened steel" gear drive?

Thanks

 

[The Big Al]

Roller cams are ground from a hard steel, not the same as cast iron (flat tappets)

You need the harder dist gear.
You can use a bronze gear.



Some roller cams have a option for a cast gear installed on a roller.
I have this option.

 

[Rambo]

I ran a bronze gear on my Comp Hyd. roller cam and it lasted about 4 years. The gear finally wore out. Comp recommended their composite gear. It is exquisitely expensive but seems to work very well. They pointed out that my bronze gear sent little flecks of bronze through my engine as it gradually failed. Next time I'll go with the composite gear again even if it dosen't outlast the bronze.