novass

iTrader: (1)

With a roller cam isn't the cam profile curve fatter than the flat tappet?

Which Cam type is more suited for a centrifical supercharged engine?



I'm looking into building a 350 forged engine for my bird and debating between a 1 piece rms (roller) and and older style block (flat tappet).

--- Tom

MrDude_1

the type of cam you choose (roller or flat tappet) is independent of the block you use.

novass

iTrader: (1)

Maybe I should have been more specific.

If I use a 1 piece rms block i will use the factory roller lifter, setup.

If I go with an older block I will probably go flat tappet.

Either way, which cam style would be better for boost.

tommyt

With a blower You wont be turning very high RPM-s, probably run up to around 6500, and in that range, a hydraulic roller would work good. I would prefer the retrofit link-bar type lifters , but the factory style lifters would work ok also. Just my preference, some may think otherwise, but
either way, a hydraulic roller will be pretty good, especially if the car is mostly street driven.

biggtime

Rollers are always better. You can open that puppy up a ton quicker! better cylinder filling in less time.

novass

iTrader: (1)

thanks for your replies guys!

83 Crossfire TA

iTrader: (2)

Never say always or someone will go out of their way to find the exception… on that note:

Flat tappets actually start to open valves faster (the edge of the tappet rides up on the side of the lobe faster, where the roller always contacts very close to the centerline). NA this is irrelevant since by the time the valve opens enough to get any airflow the roller is taking advantage of it’s faster available ramp. In a boosted situation, with a lot of boost, mild cam and really nice ports this all changes, and low lift numbers mean a lot more. In that situation there is actually an advantage in going flat tappet.

Real life, this is a pretty specialized situation and don't worry about it, go roller...