Why use plastic gear over metal gear????

I was told there is a plastic or what ever its made of for the drive gear for use in roller cam engines. I have a transplanted 89 305 Pontiac (89 used the chevy eng. that year i was told) in my 68 C10. I was told to make sure the eng. has roller lifters then make sure the dist. drive gear is the plastic type gear opposed to metal. While my eng is out I'm changing the freeze plugs,rear main 1 piece seal and pan gasket along with the front pump trans (4L60) seal and the tail housing seal. I did use a flash light and look to see if I could see roller lifters in it and YEP I have roller lifters.

Whats the usages or reason behind the two different materials used for the drive gears?.... And is there such thing as a plastic type gear?

thanks in advance for any help or links. MJ

 

I've never heard of a plastic gear in a SBC distributor. A plastic distributor gear would shred. There are different types of gears available for roller engines so maybe whoever you were talking to confused the name like a mellanized gear or a a hardened or billet gear. I think it was/is possible to get a oil pump pickup where the collar was a plastic material but I'm not sure on that.

 

There are "composition' dist gears available, from Comp Cams I know for sure, maybe others. Originally for use with billet roller cams as an upgrade from bronze.

Most likely the usual case-hardened ("melonized") ones are a better choice, for a typical hyd roller cam.

 

Here is a great article on the subject: https://www.onedirt.com/tech/engine/...compatibility/

 

Thanks that was very helpful.

 

The better hyd roller cams have an iron gear that is pressed and welded onto the billet core. These cams are to be run with the same steel dist drive gear that came from the factory on all GM hyd roller cam engines. Unless you are installing an aftermarket cam, use a stock replacement steel dist gear. If you are installing an aftermarket cam, check with the manufacturer to be sure it has an iron gear. If it doesn't send that POS back and get one that does. There is no need to ever run a roller cam that doesn't have an iron gear. Any cam grind can just as easily be done on an iron gear core as on a straight billet core.

 

Ive seen what damage can be done when those plastic gears break, pass. Bronze, track only imo
OP if you order a cam just dont order a billet dist gear and make sure your height is set up right.