Roller Cam vs Flat Tappet: Differences, Pros and Cons
A flat tappet camshaft uses lifters with a nearly flat face that slides across each cam lobe, while a roller camshaft uses lifters with a small wheel that rolls over the lobe. Roller lifters permit different lobe profiles and reduce sliding contact. They avoid flat tappet-style lobe break-in, but performance and durability still depend on the exact camshaft and matched valvetrain. Flat tappet parts cost less and suit period-correct rebuilds. Check the specification table for the exact crate engine you are considering.
Flat tappet parts cost less and suit period-correct rebuilds. Nearly all new pushrod crate engines use hydraulic roller cams.
What is the difference between a roller cam and a flat tappet cam?
| Flat tappet | Roller | |
|---|---|---|
| Lifter contact | Slides on the lobe; lifter spins slowly in its bore | Wheel rolls on the lobe |
| Lobe shape | Limited by the lifter diameter, so the valve opens more gradually | Can open the valve faster and hold it open longer for the same duration |
| Friction and wear | Sliding contact; correct oil and break-in matter | Reduced sliding contact; service life depends on the complete setup |
| Cam break-in | Required, following the cam maker’s procedure | No lobe break-in in the flat tappet sense |
| Cost | Lower | Higher: lifters, cam core and often pushrods and valve springs |
| Typical use | Older engines, budget and period-correct builds, some racing classes | Factory V8s from the late 1980s on, most performance builds and crate engines |
What is the difference between hydraulic and solid lifters?
Roller or flat tappet describes how the lifter meets the cam. Hydraulic or solid (also called mechanical) describes how the lifter takes up clearance, and either kind of cam comes in both versions.
- Hydraulic lifters use engine oil pressure to keep the valvetrain at zero lash. They are quiet and need little or no adjustment, which is why street engines use them.
- Solid lifters have no internal plunger. They need a set valve lash that is checked periodically, and in return they stay stable at very high RPM, which suits race engines.
That gives four combinations:
- Hydraulic flat tappet
- Solid flat tappet
- Hydraulic roller
- Solid roller
A “hydraulic roller cam”, the common choice today, combines roller lifters with hydraulic lash adjustment.
What roller cam design changes
Roller lifters allow camshaft designers to use different lobe profiles. The result depends on the selected cam, springs and engine combination; the lifter type alone does not establish power or idle quality. COMP Cams’ camshaft type guide describes the benefits and limitations of hydraulic, mechanical and retrofit designs. Cam lift, duration and lobe separation are explained in our lobe separation angle and cam specs guide.
How does cam break-in work?
A new flat tappet cam and its lifters must wear in together during the first minutes of running, and they depend on the anti-wear additives in the oil. A skipped or interrupted break-in can wipe a lobe. Roller cams do not have that sliding wear pattern, although a new engine still needs its own break-in for the piston rings and bearings. Always follow the procedure and oil recommendation supplied by the engine or camshaft maker; see how to break in a new engine.
Can you swap a flat tappet engine to a roller cam?
A conversion may be possible, but the block, cam retention, lifters, pushrod length, springs and drive components must suit the complete combination. Factory roller provisions and retrofit lifters are different arrangements. Have the engine builder confirm the requirements before ordering; COMP Cams’ GM technical guidance explains the model-specific considerations.
Which cam type do our crate engines use?
The following crate-engine specification tables list hydraulic roller camshafts. Examples:
- BluePrint SBC 350 (341 HP), BluePrint SBC 383 (436 HP) and BluePrint SBC 400 (500 HP)
- GM Performance 6.0L LS364/450 (452 HP) and GM Performance LS3 (430 HP)
- BluePrint SBF 347 EFI (415 HP) and BluePrint SBF 408 (450 HP)
- BluePrint 426 Gen III Hemi (610 HP) and BluePrint 427 LS (605 HP)
The Ford Coyote crate engines, such as the Gen 4 5.0L, are dual overhead cam engines and do not use pushrod lifters at all. Check each product page for the camshaft details of a specific engine, and see all crate engines.
Frequently asked questions
Is a roller cam better than a flat tappet cam?
A roller design permits different lobe profiles, but it does not guarantee more power or longer life in every build. Compare the exact camshaft and matched valvetrain for your intended use. A flat tappet design may suit a budget or period-correct build when installed and broken in as its manufacturer specifies.
What is a hydraulic roller cam?
A camshaft designed for roller lifters that use oil pressure to hold zero valve lash. It combines low friction with quiet, adjustment-free operation.
What is the difference between hydraulic and solid lifters?
Hydraulic lifters adjust themselves with oil pressure. Solid lifters need a set valve lash that is checked from time to time, and they stay more stable at very high RPM.
What does roller block mean?
In this engine context, a factory roller block has provisions for a roller valvetrain, such as the cam retention and lifter anti-rotation arrangements described by COMP Cams for OE roller small-block Chevrolet engines. The term alone does not establish which camshaft or lifters will fit.
Can you put a roller cam in a flat tappet block?
A conversion may be possible with a matched camshaft, lifters and related parts. Requirements depend on the block, cam retention and compatible drive components. Ask the engine builder or camshaft manufacturer to confirm the complete combination.
Do roller cam engines need a break-in?
The cam does not need a flat tappet style lobe break-in, but the engine still does. Follow the engine maker’s instructions.
Related: engine break-in, lobe separation angle, compression ratio, Chevy 350 engine, what is a crate engine?, all guides.
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