Flat Tappet Cams

[Zrush]

I was reading an article about how NASCAR needs to update a few things in their cars. One article was how NASCAR continues to use carburetors but virtually no cars built today utilize carburetors. The other article was in reference to cams. It stated that they continue to use "Old Style Flat Tappet Cams" which are neither as efficient nor as durable as roller cams.

Much of the cam failure that drivers experience would be eliminated with roller cams.

Our Z's have roller cams, correct? Can someone explain to me what a "Tappet Cam" is.

Vicky

[59ghia]

Hi Vicky

A "roller cam" ussually means the lifter has a small "wheel" riding on the cam lobe. Flat tappet or lifter is just that, a flat area riding on the cam, this causes more resistance. Our Z's are flat tapet or rocker arm/lash pad. This area is where the term "swipe pattern" comes from, small matched grooves "swipes" happen at this high resistance point. You never want to move rockers for this reason, those "groves" are like a finger print, each cam lobe makes their own on its tappet. Now you can get roller lifters also, there again is a small steel wheel that rests on top of the valve stem (you need a lash pad when you run these) This equals even less valve train resistance.

Hope it helps,

Dave

[LanceM]

The other thing to remember is that a Z is an over head cam engine so except for the late ZX models dosen't have "lifters". Engines with internal cams like an older V-8 had lifters (tappets) that rode on the cam and pushed pushrods to operate the rocker arms which opened the valves. I find it hard to belive that NASCAR is still runing flat tappet cams, but then I don't follow NASCAR....