EC Answers: Cam Core Differences, Welded vs. Non-Welded, and What Works Best for Your Engine
One of the most common questions we receive revolves around camshafts used in Honda-based clone engines. Builders frequently ask things like:
• What’s the difference between cam cores?
• Which cam fits my engine?
• Do I need to change cams if I install a stroker kit?
• What’s the difference between welded and non-welded cams?
This article breaks down the differences between the most common cam cores, explains where each one works best, and helps you avoid common pitfalls related to engine platforms, part combinations, and performance modifications.
Predator 212 Non-Hemi
We’ll start with the Predator 212 Non-Hemi, because understanding this engine requires understanding why it exists and why it differs from nearly every other Honda-based clone.
The Honda GX series is one of the oldest overhead-valve power equipment engines on the market. As the patents on these designs began to expire, Chinese manufacturers started producing clone engines. Honda faced difficulty enforcing patents overseas, so instead pursued legal action against U.S. retailers—most notably Harbor Freight. Honda ultimately won settlements, but Harbor Freight worked around the patents by making subtle yet significant design changes.
The result was the Predator 212 Non-Hemi, which is arguably the most altered and least interchangeable Honda-style clone ever produced. Many components do not interchange with standard Honda or clone engines, including dowel pin sizes, flywheel taper, and—most importantly—the camshaft core itself.
We cannot stress this enough: the Predator 212 Non-Hemi is the worst platform for performance modifications. Even in stock form, there are multiple engines on the market that are stronger, more durable, and offer better long-term performance potential.
The popularity of the Predator 212 Non-Hemi originally stemmed from its cylinder head design. The non-hemi head used slightly larger valves than a 196cc engine and had aftermarket support—billet rocker arms, valve cover spacers, and billet valve covers were readily available. The valvetrain was lighter and more stable than the hemi variant, making it arguably easier to build for higher RPM combinations.
Early karting rules even allowed builders to pair a Hemi bottom end with a Non-Hemi head to increase compression. The Hemi used a flat-top piston, while the Non-Hemi head had a smaller combustion chamber with more quench area. Those rules have since changed, and newer, more capable engines have entered the market.
The Cam Core Problem
One of the biggest limitations of the Predator 212 Non-Hemi is its unique cam core. The cam journal boss is larger than that of standard Honda and clone engines(Predator 212 Non-Hemi .558" vs .550" for standard Honda/Clones). To our knowledge, it is the only clone engine that uses this specific cam core.
Because of this:
• Camshafts cost more
• Availability is limited
• Many retailers do not stock them
• They are often drop-shipped directly from cam grinders
• Parts do not transfer well to other platforms
When it comes to stroker combinations, this engine becomes even more problematic. While we have developed numerous stroker kits designed for easy installation across many platforms, the Predator 212 Non-Hemi is not one we support. Clearancing issues—particularly around the compression release with 58mm or longer stroke crankshafts—make it labor-intensive and costly.
Labor is the most expensive part of engine building. In many full builds, every component is replaced except the block. Unfortunately, the Predator 212 Non-Hemi block is thin, lacks reinforcement, and is arguably the weakest block on the market. This makes the investment difficult to justify.
Our recommendation is simple: use a platform that accepts the 224 cam core, which the Predator 212 Non-Hemi does not. Doing so saves money, reduces labor, and opens the door to far more performance options.
What Cams Fit the Predator 212 Non-Hemi?
Only camshafts(.558" cam boss) designed specifically for that engine will fit. Parts rarely transfer to other engines, and other engines’ parts rarely fit it. For the same investment, better platforms exist that are easier to build and offer greater performance potential.
Standard Honda-Clone Cam Core
(Also referred to as Hemi, Honda, or Clone)
This cam core fits most original Honda GX-series engines under 200cc and nearly all common clone engines. The cam journal bosses are smaller(.550" cam bosses) than the Predator 212 Non-Hemi(.558" cam bosses) and are far more standardized.
Engines that use this core include:
• 196cc clones (BSP, Ducar, Coleman, etc.)
• Predator 212 Hemi
• Tillotson / Ducar 212
• Tillotson 196R / RS
• Tillotson 212R / RS
• Tillotson 225R / RS
Other engines such as:
• Predator 224 Non-Hemi
• Wildcat 223
• Wildcat 240
• Engines using 58mm or longer stroke crankshafts
can use standard core cams, but require clearancing. The wider counterweights on longer-stroke crankshafts interfere with the compression release mechanism and spring.
We covered this extensively before the 224 core became widely available. While it is possible to clearance the cam or crank yourself, the time involved often outweighs the cost savings. In most cases, it is faster, cleaner, and more reliable to simply use a 224 core camshaft.
For performance builds, starting with one of the platforms listed above simplifies the process dramatically. Stronger blocks, better aftermarket support, and minimal clearancing make these engines far easier to build correctly.
224 Cam Core
(Wildcat 223 / 240, Ducar & Predator 224 Non-Hemi)
The 224 core uses the same cam journals as standard Honda and clone engines(.550" cam bosses), allowing it to fit nearly all of them—except the Predator 212 Non-Hemi.
These cores originated in engines like the Wildcat 223 and Ducar 224 Non-Hemi. The Predator 224 Non-Hemi uses a nearly identical cam, though often with a plastic cam gear.
Key differences between standard and 224 cores include:
• Narrower cam gear (approximately .300" thick vs .316" for standard[196cc/212cc] cam gears
• Narrower compression release (approximately .160" measured from cam gear vs .200" for standard[196cc/212cc] compression release)
• Slightly narrower lobes to clear longer stroke crankshafts and connecting rods (approximately .275" vs .365" standard[196cc/212cc] lobes)
We have progressively transitioned most of our cam offerings to the 224 core. While slightly more expensive, they provide unmatched flexibility. Customers can later upgrade to a stroker crank without replacing the cam or worrying about compression-release clearance.
Clearance concerns with 224 cores are typically related to cam profile and phasing, not the core itself. Higher lift cams often require smaller base circles to maintain clearance. Base circle dimensions vary by manufacturer and cam model, so some clearancing may still be required depending on stroke length and cam selection.
Billet Cam Cores
Billet cam cores are machined from tool steel rather than cast gray iron. They are significantly stronger and harder and are available in both standard clone cores and Predator 212 Non-Hemi cores.
These cams do not use compression releases, eliminating clearance issues entirely. However, they are not compatible with pull-start applications and are intended for high-performance engines using external electric starters. We highly recommend billet cams for engines turning over 8,000 where compression release mechanism could fail.
Welded vs. Non-Welded Camshafts
Non-Welded Cams
Most stock camshafts are made from gray cast iron and rely on heat treatment for durability. These cams are best suited for stock engines or mild builds using single valve springs and low seat pressures.
How to identify a non-welded cam:
• Typically under .285” lift
• Commonly sold on Amazon or eBay
• Usually priced under $75
• No visible weld line on the lobes
On our website, we clearly separate welded and non-welded cams to avoid confusion.
Hard-Welded Cams
Welded cams are machined, slotted, and hard-welded with specialized material to withstand higher spring pressures and RPMs. These cams are more expensive due to material and labor costs.
As a general rule:
• Cams over .300” lift should always be hard-welded
• Some lower-lift welded cams exist, but higher lift demands it
• Visable lines on the lobe of the welding rod material
What Wipes Out a Cam Lobe?
The difference between non-welded and welded camshafts ultimately comes down to their ability to survive higher valve spring pressures and sustained RPM. It is extremely rare to see a properly manufactured welded camshaft wipe out a lobe. Non-welded cams, however, are more susceptible under aggressive conditions. That said, the majority of factors that contribute to cam lobe failure apply to both styles of camshafts. Understanding these factors is critical to building a reliable engine.
Cam Material & Heat Treating
Most non-welded camshafts are manufactured from gray cast iron, which is relatively soft compared to billet or hard-welded materials. While heat treating can improve surface hardness, there is a limit to how hard these cams can be made. In most cases, the heat treatment primarily affects the surface of the lobe. Once that hardened surface begins to wear, material loss accelerates rapidly and lobe failure soon follows.
It is also important to understand that heat treatment consistency can vary, meaning some non-welded cams are inherently more durable than others. This is why following the recommendations of the cam grinder or manufacturer regarding spring pressure, rocker type, RPM limits, and application is critical to preventing premature wear or failure.
Valve Spring Pressure
Valve spring pressure is one of the most common contributors to cam lobe failure. Non-welded camshafts are not recommended for use with dual valve springs or seat pressures exceeding approximately 28 lb. Springs are typically rated by seat pressure at a specified installed height, such as 22 lb or 26 lb. However, actual spring pressure can vary significantly depending on the installed height and retainer configuration.
In addition to seat pressure, spring pressure increases as valve lift increases—commonly referred to as “over the nose” pressure or pressure at maximum lift. This is the primary reason camshafts above roughly .285” lift generally require hard welding. While two camshafts may share the same seat pressure, their over-the-nose pressures can be dramatically different. For example, a .265” lift cam and a .308” lift cam may both use a 26 lb seat pressure spring, yet the .265” cam may see approximately 42 lb at max lift, while the .308” cam may exceed 50 lb. That additional load is transferred directly to the cam lobe and tappet interface.
Rocker Ratio
Increasing rocker ratio introduces another significant variable. Rockers that increase ratio are typically billet rocker arms, which are heavier than stock-style stamped or cast rockers. This added mass, combined with increased valve lift and acceleration, demands higher spring pressure—especially as RPM increases.
A common question we receive is whether billet rocker arms can be used with cams such as our Banzai or similar non-welded profiles. The short answer is no. While seat pressure may remain unchanged, increasing rocker ratio increases valve lift, which in turn raises over-the-nose spring pressure.
For example, using a 26 lb spring with a .265” cam may result in approximately 42 lb at max lift. Adding a 1.2:1 rocker increases valve lift to roughly .318”, pushing over-the-nose pressure beyond 50 lb. At that point, additional spring pressure—or even a dual valve spring—is often required to control valve motion and prevent float at higher RPM.
Our dual “32 lb” springs(approximately .930”), for instance, typically measure around 45 lb of seat pressure at the same installed height as a 26 lb spring (approximately .815”). Due to their higher spring rate, they can reach 70 lb or more over the nose, which is roughly 20 lb higher than a comparable 26 lb spring. As a general rule, non-welded cams should only be used with stock-style rocker arms.
Cylinder Pressure
In small engines, camshaft and valvetrain failures most commonly occur on the exhaust lobe. This is because the exhaust valve begins opening while there is still significant cylinder pressure present. As the valve opens, the camshaft must overcome both valve spring pressure and the remaining combustion pressure in the cylinder.
As compression ratio increases—or ignition timing is advanced, particularly to the point of detonation—the load placed on the exhaust lobe increases substantially. Camshaft design also plays a role. Profiles with longer duration, wider lobe separation angles, or advanced cam timing can cause the exhaust valve to open earlier, when cylinder pressure is still high. This increases stress on the cam lobe and tappet face.
If cam lobe wear is occurring and spring pressure is not the root cause, the next steps should be to reduce ignition timing, lower compression if possible, and increase fuel octane to reduce detonation and peak cylinder pressure.
Oil Selection and Chemistry
Oil is often assumed to be the primary cause of camshaft failure, but it is rarely the sole factor. Stock engines frequently run low-quality oils and still survive because they operate with low spring pressures, low valve lift, conservative timing, and modest compression.
That said, oil can absolutely be either part of the problem or part of the solution. These engines use flat tappet valvetrains, and most modern automotive oils lack the appropriate anti-wear chemistry required for this design. Zinc is commonly referenced in this context, but it is often misunderstood. When discussing zinc, we are actually referring to ZDDP (zinc dialkyldithiophosphate), which functions as an anti-wear additive.
ZDDP levels were reduced in modern oils due to emissions system requirements in newer vehicles that use roller valvetrains. While oil chemistry has evolved to compensate in those applications, flat tappet engines still rely on proper ZDDP activation. Simply adding a zinc additive to standard oil is not an effective solution. In fact, doing so can dilute the oil and interfere with its chemistry, sometimes increasing wear rather than reducing it.
Too little ZDDP can be problematic, but too much can be just as damaging. ZDDP relies on other oil chemistry and requires heat and pressure to properly bond to metal surfaces. Break-in oils are specifically formulated to allow ZDDP to activate quickly during initial camshaft run-in. Adding zinc additives to conventional oil does not replicate this process. Selecting an oil formulated for your specific engine and application will produce far better results.
Lifter and Tappet Replacement
Whenever a camshaft is removed, it is critical that tappets remain in their original locations. Swapping intake and exhaust tappets disrupts established wear patterns and can rapidly accelerate cam lobe wear. Tappets are significantly harder than non-welded cam lobes, and once the cam’s surface hardness is compromised, failure occurs quickly.
When installing a new camshaft, new tappets should always be used, and the engine should be broken in using proper break-in oil and procedures to establish correct wear patterns from the start.
Following these guidelines will significantly improve camshaft durability and overall engine reliability—whether you are using a non-welded, hard-welded, or billet cam core.
