Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit www.motortrend.com for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM
Subscribe to the Free

10 Quick Tips for Swapping to a Hydraulic Roller Camshaft

Roll With It

Tommy Lee Byrd Aug 25, 2016
View Full Gallery

With the availability and efficiency of roller camshafts it’s a no-brainer to use a hydraulic roller setup even on the simplest of engine combinations. The roller lifters take a lot of load off of the valvetrain and it frees up a few horsepower compared to the old flat tappet design. Whether you’re dealing with a hydraulic roller or a more race-oriented solid roller camshaft, there are a few additional modifications that you need to know about before you fire the new combination.

Some of the tech tips listed here are geared toward making a little more horsepower while others are simple steps to ensuring your engine will withstand plenty of abuse. We consulted with Comp Cams regarding the necessary steps for swapping your old-school engine to a hydraulic roller setup, and they happened to have all of the necessary parts to make it work. Some of the parts come with Comp’s complete kits, while others are standalone items that you’ll need to purchase separately. Thankfully, the tech support guys at Comp helped us get our 327ci small-block updated with a hydraulic roller retrofit kit with all of the associated components.

Even though it isn’t quite as simple as sliding a new camshaft into the block and re-assembling the top end of the engine, the process is worth every penny and every hour spent in the garage. The roller system is more reliable, more efficient, and it gains you a few car guy points at the cruise night. Take a look at our top 10 tech tips to consider when swapping your flat tappet camshaft for a roller system, and get your old-school small-block ready for action.

Roller Flat Tappet Conversion Tips Installing Endplay 02 2/11

1. Regardless of the manufacturer you choose, always select the most complete kit when swapping from a flat tappet camshaft to a roller setup. We would suggest kits that contain the camshaft, lifters, and valvesprings as a starting point; companies like Comp Cams offer even more complete kits. This is a Comp Cams Xtreme Energy retrofit hydraulic roller kit (PN K12-432-8), which is an excellent choice for a high-performance street engine.

Roller Flat Tappet Conversion Tips Installing Endplay 03 3/11

2. When installing a hydraulic roller camshaft, you’ll need a particular type of distributor gear. Most roller camshafts are manufactured from billet steel (compared to cast iron), and this is the culprit for the gear wear issues. A standard cast-iron distributor gear will wear against the steel gear on the camshaft and eventually do damage, which is not an easy fix. A melonite-treated steel gear is typically the most affordable and longest lasting, while other options like bronze or composite are also available.

Roller Flat Tappet Conversion Tips Installing Endplay 04 4/11

3. One of the biggest advantages of a roller camshaft is the lack of friction between the lifter and the camshaft lobe. This means that the awful stories of wiping a lobe off a brand-new camshaft is way less likely with a roller. However, it’s still very important to use a dedicated camshaft and lifter assembly lube when installing the system. Assembly lube on the lobes and a little bit of heavy weight oil on the journals, and you’re good to go.

Roller Flat Tappet Conversion Tips Installing Endplay 05 5/11

4. A roller camshaft uses a thrust button to restrict the fore and aft movement of the camshaft. This button is not required on a flat tappet design due to the tapered design of the lobes, but the flat surface of the roller tappet allows the camshaft to walk forward and rearward. Comp Cams sells a steel roller button that is a fixed length that requires the use of shims to achieve the proper tolerance. The nylon button pictured is also a Comp Cams product, and it is a file-fit design. The idea is to limit camshaft endplay to 0.005-inch. Excessive camshaft endplay can result in erratic timing issues as well as premature distributor gear wear.

Roller Flat Tappet Conversion Tips Installing Endplay 06 6/11

5. Hydraulic roller lifters, like the ones in the Comp Cams retrofit kit, feature a link bar that ties the intake and exhaust lifters together. If you’re working on a fresh build, you might consider running a hone through the lifter bores to ensure a super smooth surface for your new lifters. Comp Cams suggests cleaning the lifters with mineral spirits before pre-soaking them in oil. The pre-soak is not mandatory but it helps lubricate the outer surfaces and ensures a quieter start up. Always coat the roller with assembly lube as you’re sliding them into the bores.

Roller Flat Tappet Conversion Tips Installing Endplay 07 7/11

6. One often-overlooked aspect of a roller camshaft swap is the fuel pump pushrod. Similar to the conflict of the distributor gear material and the camshaft core material, a standard fuel pump pushrod can actually damage a camshaft that is made from billet steel (this accounts for pretty much all roller camshafts). Comp Cams offers a lightweight pushrod (PN 4607) that features a bronze tip on the end that comes in contact with the camshaft.

Roller Flat Tappet Conversion Tips Installing Endplay 08 8/11

7. While Comp Cams and other companies do offer complete kits that include pushrods, it’s a good idea to measure for the appropriate length pushrod. Roller setups require a shorter pushrod, due to the taller lifter body, and all sorts of factors (deck height, head gasket thickness, and more) go into determining proper pushrod length. We suggest buying a pushrod length checker, as they are affordable and easy to use. Valvetrain geometry is very important and the idea is to center the rocker arm on the valve stem. The only way to accomplish this is with the correct length pushrods.

Roller Flat Tappet Conversion Tips Installing Endplay 09 9/11

8. We like the idea of using a two-piece timing chain cover because it makes camshaft swaps a little easier. There is another advantage to a two-piece cover, or an aluminum timing chain cover in general, and it involves strength. A standard stamped steel timing chain cover may flex as the camshaft tries to walk forward. Reinforced steel timing chain covers are available if you’d prefer the stock look, but we like the race-ready look and the rigid construction of this Comp Cams two-piece aluminum setup.

Roller Flat Tappet Conversion Tips Installing Endplay 10 10/11

9. Valvesprings are crucial to any valvetrain, whether it’s a flat tappet or roller design. This is another instance where buying a complete kit comes in handy as most street-friendly combinations will work nicely with the provided valvesprings. If you’re doing the homework to determine the appropriate valvesprings, be sure to account for the added lift from high-ratio rocker arms. Running a set of 1.6:1 ratio rocker arms may be pushing the limits of your valvesprings if you ordered them based on the cam card specs, which are typically formulated using a 1.5:1 rocker ratio.

Roller Flat Tappet Conversion Tips Installing Endplay 11 11/11

10. Any time a new camshaft and lifters are installed it’s important to break in the components using high quality break-in oil. Even though a roller camshaft is less likely to lose a lobe on initial startup (compared to a flat tappet) it’s still a good idea to bring the rpms up as soon as the engine comes to life. Alternating between 2,000 and 2,500 rpm during that initial break-in ensures proper oiling for the valvetrain. Drain the break-in oil, change the filter, and pour in your favorite high-performance oil before taking a long trip or hitting the racetrack to test out the new camshaft.


Comp Cams
Memphis, TN 38118



Connect With Us

Get Latest News and Articles. Newsletter Sign Up

sponsored links

subscribe to the magazine

get digital get print