[ponyakr]

Bullet can also grind any of the old Ultradyne lobes. Their HR lobes are listed at the bottom of this linked page.


http://www.bulletcams.com/Masters/ultradynemasters.html

[ponyakr]

"...what would be the point of a roller cam ground to HFT specs?..."


POSSIBLY to lower spring pressure, and / or to reduce the friction produced by the direct contact of flat tappet lifter and lobe ? Possibly slightly better gas mileage ?

But mostly to reduce the chance of flat tappet cam failure. Obviously there are those who have posted in this thread who have seen LOTS of flat tappet cam failures, over the past several years. But there are others who say all the failures were caused by improper break-in. So, WHO'S right ?

Are flat tappet cams more likely to fail or NOT ??? If they are not, then most all daily driver engines can get by with flat tappet cams. BUT, if they are, then the HR cam may be a good investment.

It seems that every cam thread turns into a debate, with differing opinions on almost every aspect of cam/lifter choice. But, I suppose it's good entertainment, and everybody will just have to read and decide who to believe.

So, let the debate continue !

[gtofreek]

Like I say, we build a lot of engines with FT cams. In the 10 years I have been at Koerner Racing Engines we have only seen 1 FT cam go bad. So why is that? If it is the fault of the cams, then why have we not had problems with it. We have seen far more roller lifter and cam failures than FT. We recently had a roller cam that wasn't hardened correctly, and it ate the lobes up in less than 5000 miles.

Not turning this into a FT/roller cam debate[I don't care either way, as I use both], just saying that both types can have issues. Some people think that just because they go to roller cam setup, that it will completely eliminate any cam/lifter related issues they might have. I'm just saying, not necessarily.

[Will]

Originally Posted by gtofreek

...
Not turning this into a FT/roller cam debate[I don't care either way, as I use both], just saying that both types can have issues. Some people think that just because they go to roller cam setup, that it will completely eliminate any cam/lifter related issues they might have. I'm just saying, not necessarily.

Absolutely. There are plenty of instances of roller cam failures out there. Like I said, these are aftermarket parts built for a retrofit application, not OEM designed from the ground up.

Thing is, when a roller goes bad the failure can often be catastrophic - breaking lifter bores & such. Usually you catch a flat tappet going bad because it starts making noise. Yeah, you get some metal through the engine but if you catch it quick enough this usually isn't catastrophic and you might not need to do anything other than replace cam & lifters. Break a lifter bore and the block is done vs. maybe new bearings and a re-hone.

That said, I like the performance advantage of rollers and would always choose one if the budget allows. As mentioned above, no reason you can't run a mild roller that produces a stock type idle and doesn't require really high spring pressures and it'll still make more power than a stock cam.