MILD THUNDER

I recently learned that a flat tappet cam, can actually have higher lifter acceleration rates than a roller, depending on the specs. I was always told the rollers were much more aggressive ramp rates, but that apparently isn't always true.

Black Baja

A flat tappet opens the valve quicker until it hits the valley before going over the nose. There is no mechanical advantage to a roller lifter.

Black Baja

There are companies that know how to make a good flat tappet core. They have got the heat treat process down to a science now and are able to run an uncoated tool steel lifter on an 8620 core. But the heat treating takes an extra step.

MILD THUNDER

From Jones cams

We still parkerize all our cast cams, except for the ones we nitride. Parkerluberite(parkerizing agent) is an acidic lubricant that eats it's way into the surface of the cast iron, and protects against galling during break-in. It does not harden the cam.

Nitriding hardens the outer .003" of the cam, and the gray layer that's formed also protects against galling during break-in.

We finish grind the cams before we nitride them. The special nitriding process we use(Ion Nitriding) allows us to nitride at around 800-F, so the distortion is very small. We actually introduce an oxide treatment at the end of the nitriding, so our cams come out looking black.

There is two problems we see with Nitriding flat tappets.
One, if you run a lifter that's too close in hardness to the surface hardness of the nitrided cam, the two metels will gall.
Two, when nitriding, the outer surface gets hard, but below that thin layer of hardness, the nitriding can actually lower the hardness. This will cause what I call a pie crust effect, and the soft material below the hard outer surface will give way, and the hard surface will crack and flake off.

mike tkach

i have never seen a steel flat tappet cam,for the 40 years i used them they were all iron.

mike tkach

last year i built 2 flat tappet engines,they both had no lobe problems but i still get nervous when i install one.

vintage chromoly

Did you use EDM lifters mike?

Black Baja

8620 is commonly used. If you wanna step up to the big boy flat tappet stuff it's Tool steel cams and lifters.

mike tkach

yes.162 bucks from summit for the 396.the 2 i did last year,a chevy 327 and a pontiac 389 i used the crower cam saver lifters with a flat ground on the side.they seem to work ok.crower claims the cam saver lifter puts 30 % more oil on the lobe&btm of the lifter

getrdunn

It's always easy to tell by the choppy idle. Valako always gave me **** over running them just for that very reason.