Don Terrill’s Speed-Talk

Why is it that I almost never hear about nitriding cams anymore? Have we found that it is not as awesome as first thought? I remember Compcams heavily advertised it a few years ago. Now, not so much. What is the current thought?

paulie

EDM type flat tappet lifters may have made this obsolete/ unnecessary.

I still have it done.

Nitriding still has it's place, in my opinion and experience. When the valve spring pressures are reasonable, it helps with break in, which is critical. Nitriding changes the core material hardness, so this has to be considered. When the spring pressures get up there on a flat tappet application, break in takes a back seat to cam longevity. In these situations, break in can be approached several ways.

In short, you have to look at the whole package....the type of lifters you're going to run, valve spring pressures, valve weight, etc.

I've been saying for years, when you nitride a cast iron cam, the process reduces the core hardness of the material. You end up with a very hard, but thin outer layer, but the backing material is now much softer. The hard shell. helps with break-in, but the after a while the softer backing material gives way, and the hard shell starts to flake off. As soon as that starts, your cam is toast.

CamKing wrote: ↑Mon Sep 24, 2018 9:55 am I've been saying for years, when you nitride a cast iron cam, the process reduces the core hardness of the material.

Mike,
What about steel billet cams?

Thanks guys!

So what is cutting edge for high spring pressure flat tappet cams?

paulie

plovett wrote: ↑Mon Sep 24, 2018 8:13 pm Thanks guys!

So what is cutting edge for high spring pressure flat tappet cams?

paulie

Tool steel, with DLC or similar coated lifters is about as good as it gets.

Next best alternative is good cast core (Pro 55 or similar) with polished lobes and tool steel lifter(not coated).

What is/was NASCAR using for their solid lifter flat-tappet cams!

Oh, and if I had the money and was anal about this, I would make my cam out of 300M that is tempered for a cam application and be done with it.

Temper it up around 62 Rc if it would do it? Then I would see if the diamond coated lifters would be compatible?

pdq67

Charliesauto wrote: ↑Mon Sep 24, 2018 8:33 pmTool steel, with DLC or similar coated lifters is about as good as it gets. Next best alternative is good cast core (Pro 55 or similar) with polished lobes and tool steel lifter(not coated).

This ^^^^^^^

Where do Isky's old, "chilled iron" lifters come fit in here?

pdq67

pdq67 wrote: ↑Tue Sep 25, 2018 12:28 pm Where do Isky's old, "chilled iron" lifters come fit in here?

pdq67

Chilled iron lifters were used by GM on the steel cams used on Chevy and GMC inline 6's up to the early 50's when GM changed to cast cams using hardenable iron lifters...