What do you call an engine with its camshaft in the block?

An engine with its camshaft in the block is generally called a cam-in-block engine; most commonly, that means an overhead-valve (OHV) or “pushrod” engine. If the camshaft and the valves both sit in the block, it’s a flathead (also called sidevalve or L-head). In everyday automotive usage, “cam-in-block” most often refers to OHV/pushrod designs, which remain widely used alongside overhead-cam (OHC/DOHC) architectures.

How the terminology works

Camshaft placement defines broad engine families. With cam-in-block designs, the camshaft lives in the engine block rather than in the cylinder head. That single fact covers two distinct valve layouts: pushrod OHV engines, where the cam actuates valves in the head via lifters, pushrods, and rocker arms; and flatheads, where both the cam and the valves are in the block, and the combustion chamber shape is different.

Common names and what they imply

The following terms are frequently used to describe engines with a camshaft in the block, each with a specific nuance about valve placement and actuation.

• Cam-in-block: The umbrella term for any engine with its camshaft located in the block, regardless of where the valves are.
• OHV (overhead valve): A cam-in-block engine that uses pushrods to operate poppet valves located in the cylinder head.
• Pushrod: Informal shorthand for OHV, emphasizing the valvetrain components that transmit motion from the cam to the valves.
• Flathead (sidevalve, L-head): A cam-in-block design where the valves are also in the block, adjacent to the cylinder, rather than in the head.

In contemporary conversation, “cam-in-block” almost always implies OHV/pushrod unless someone explicitly mentions flathead, a layout that is now largely historical in automotive use.

How it differs from OHC/DOHC designs

Overhead-cam engines put the camshaft(s) in the cylinder head above the valves, eliminating pushrods. This can reduce valvetrain mass and complexity at high rpm and makes multi-valve and aggressive variable valve timing strategies more straightforward. Cam-in-block OHV engines, by contrast, route motion through lifters and pushrods to rocker arms, which adds components but enables a lower-profile cylinder head and a compact overall package.

Advantages of cam-in-block (OHV/pushrod) engines

Engineers and automakers still choose OHV for particular strengths that fit certain packaging and performance goals, especially in V8 truck and sports-car applications.

• Compact packaging: Short cylinder heads and a lower overall engine height ease installation and improve underhood packaging.
• Robust low- to mid-range torque: Valvetrain geometry and long-stroke V8 pairings often deliver strong torque where street and towing applications need it.
• Simplicity and durability: Fewer cams and timing drives can mean lower parts count and proven longevity in heavy-duty cycles.
• Cost and mass efficiency: One camshaft and simpler heads can reduce manufacturing cost and, in some cases, overall engine mass.

These attributes help explain why OHV V8s remain prevalent in full-size pickups, SUVs, and some performance cars despite the proliferation of OHC/DOHC designs.

Trade-offs compared with OHC/DOHC

Cam-in-block layouts also carry limitations that influence where they’re chosen and how they’re tuned.

• High-rpm ceiling: Additional valvetrain mass and pushrod deflection can constrain sustained very-high-rpm operation compared with well-executed DOHC systems.
• Valve control complexity: Implementing four valves per cylinder and intricate variable valve timing is more challenging and less common in OHV designs.
• Combustion chamber flexibility: DOHC layouts offer more freedom for multi-valve combustion-chamber shaping and extreme valve timing events.

Modern engineering mitigates many of these issues, but they remain key design considerations when choosing between architectures.

Notable modern and historical examples

Cam-in-block engines span more than a century of powertrain history, from early flatheads to today’s high-tech pushrod V8s.

• GM small-block V8 (LS/LT series): Modern OHV pushrod engines in Chevrolet and GMC trucks and SUVs, and in the Corvette Stingray (LT2). The Corvette Z06’s LT6 is a separate DOHC engine, illustrating GM uses both approaches.
• GM 6.6L L8T V8: An OHV gasoline engine powering Silverado and Sierra HD pickups.
• Stellantis “Hemi” V8s (5.7L, 6.4L): OHV pushrod designs used widely in Ram trucks and recent Dodge performance models; some light-duty applications are transitioning to twin-turbo DOHC inline-sixes, while heavy-duty gas V8s persist.
• Harley-Davidson Big Twin V-twins: Classic motorcycle pushrod engines with cam(s) in the crankcase (the “block”).
• Ford Flathead V8 and Willys “Go-Devil” L-head: Historic flathead car and military Jeep engines with both cam and valves in the block.

Together they show the breadth of cam-in-block engineering—from simple sidevalves to sophisticated, emissions-compliant pushrod V8s delivering modern performance.

Why the terminology can be confusing

People often use “cam-in-block” and “OHV” interchangeably, but the former is the broad mechanical layout while the latter specifies overhead valves operated by pushrods. Flatheads are also cam-in-block, yet they don’t have overhead valves. When precision matters, naming the valve arrangement—OHV/pushrod versus flathead—avoids ambiguity.

Summary

An engine with its camshaft in the block is called a cam-in-block engine. In contemporary practice, that usually means an OHV or “pushrod” engine, though historically it also includes flatheads with valves in the block. OHV designs persist because they package neatly, deliver stout real-world torque, and are durable and cost-effective, even as OHC/DOHC architectures dominate where very high rpm, multi-valve layouts, and extensive valve timing control are paramount.