Flat tappet or Roller?

jake

Senior Member
Joined
Oct 23, 2012
Messages
1,537
Reaction score
1,079
Location
wisconsin
Building a stroked 383, something to cruise and street beat a little with. Keeping it under 5500 rpms. Is it worth the extra grand to go roller step up on the street? I have not wiped a cam yet on flat tappets? I would rather wipe a cam then have needle bearings from a bad roller lifter sent through my motor. FYI, my flat tappet lifters in the existing engine are about 5 years old and plan on reusing them as they do not leak down.
Thoughts? TIA
 
Building a stroked 383, something to cruise and street beat a little with. Keeping it under 5500 rpms. Is it worth the extra grand to go roller step up on the street? I have not wiped a cam yet on flat tappets? I would rather wipe a cam then have needle bearings from a bad roller lifter sent through my motor. FYI, my flat tappet lifters in the existing engine are about 5 years old and plan on reusing them as they do not leak down.
Thoughts? TIA

You can not use flat tappet lifters on any cam except the one they were installed on. They are mated to the flat tappet camshaft. Also means that they need to go back into the same lifter bores that they came out of. Flat tappet cams are generally more reliable for a street engine that was designed for a flat tappet cam. Comp Cams and others have had issues with the riveted cross links breaking. When this happens, the roller turns sideways and the cam is instantly wiped. You can avoid the breakage issue by using keyed lifters, but this involves a lot of expensive machine work. My vote for anything except an extreme performance engine would be to stay with a flat tappet cam.

You would expect to gain about 10 horse power with the roller cam on a moderately built engine because they operate with a lot less friction. The choice is yours if you feel the few extra horses is worth it.

Dave
 
Last edited:
Other than friction reduction, the shape of the roller cam lobe usually has more area under it than a flat tappet lobe will. Roller lobes are usually taller, too, by observation, which can also mean piston/valve clearance issues. Lots of lift and short duration will wear valve springs much quicker than a milder "less intense' lobe, by observation. Better to have a bit less lift and a bit more duration, comparatively speaking.

Lunati and some Comp Cam hydraulic flat tappet cams have assymetrical-shaped lobes. Quicker initial lift, hold the valve at max lift a bit longer, then a slower closing. All of which puts more "area under the lift curve" for a given valve lift.

Just some thoughts,
CBODY67
 
I think you answered your own question. For what you want, a flat tappet will be cheaper and give you piece of mind. Not to mention, it's what your engine was built with. Gotta love natural compatibility.
 
Just need to find a reliable source for higher-zddp motor oil, which is better today than years ago. You can also invest in full-roller rocker arms for friction reduction, too.

Enjoy!
CBODY67
 
Back
Top