There is a long list of advantages when it comes to converting your small-block or big-block Chevy to a roller camshaft. Decades ago, only serious racers had roller camshafts, but now it’s a no-brainer to upgrade to a roller setup, even for the tamest street configuration. Roller camshafts offer horsepower and torque increases, based purely on the efficiency of the valvetrain. However, there are quite a few details of the swap that can create problems if not addressed properly. One of the most important aspects is camshaft endplay.
Setting camshaft endplay is crucial to the life of your camshaft and lifters, and ultimately your engine. Stock small-block and big-block engines do not require any type of endplay adjustment, as a flat tappet camshaft features tapered lobes that force the camshaft to the back of the block. This self-aligning feature isn’t available on roller camshafts as the lobe and the lifter face are completely flat. Ideally, the roller lifter is centered on the lobe, and if a camshaft has too much endplay it will allow the camshaft to “walk” forward. This puts the roller at the edge of the lobe, which can cause major damage to the lifter and the camshaft.
Another unfortunate byproduct of a camshaft with excessive endplay is irregular wear on the distributor gear. It’s also important to note that any forward movement of the camshaft also retards the ignition timing. Comp Cams suggests 0.004-0.010-inch of endplay, which is obviously very minimal. Any more than the suggested endplay will result in erratic timing, and since the timing is retarding as the camshaft walks forward, you are losing horsepower up top. This inconsistent timing will drive you crazy if you’re troubleshooting a loss of horsepower, or the feeling of your car “nosing over” in high-rpm situations due to the timing jumping around.
Camshaft endplay is adjusted with a thrust “button,” which rides on the front side of the camshaft. It rides against the timing chain cover, and serves as a stop for the camshaft. You can get a couple types of buttons: one is a steel roller and the other is a nylon button. The steel roller uses shims to space it out to the desired tolerance while the nylon button is a file-fit design. Both require some trial and error, and either button is good for street engine or race engines. The roller button offers a little more longevity but it’s truly a matter of preference. We chose a nylon thrust button for this particular small-block build.
Even if you set the endplay to the suggested value there is a chance that a stock timing chain cover will flex due to the force from the camshaft. Stock stamped steel timing chain covers are not strong enough to offer consistent endplay in a high-performance engine so we swapped to a two-piece billet aluminum cover from Comp Cams (PN 210). This cover can be installed on an engine with a flat tappet camshaft, but a strong cover is a must for retrofit roller setups like the one we’re using in this small-block. Other covers are available, including a stock-appearing steel unit with a welded thrust plate from Comp (PN 208).
Follow along as we install the new aluminum timing chain cover, and set the endplay on our new retrofit hydraulic roller camshaft. It’s a crucial step in making sure this engine survives and makes the most horsepower possible. So if you want to take full advantage of a roller camshaft you need to take the time to set the endplay.
1. No matter the effort you make to measure your camshaft endplay, it will defeat the purpose if your stock stamped steel timing chain cover flexes. That’s why we’re installing a Comp Cams two-piece billet aluminum timing chain cover (PN 210).
2. Before we get started with setting the endplay, we install the base for the two-piece timing cover using two of the supplied bolts. In order to determine the proper amount of endplay you must install the base with the supplied gasket.
3. Make sure the end of the camshaft is clean of any debris, even oil, as any interference can cause a miscalculation in the endplay.
4. Now, we can install the timing set. The nylon button is a file-fit piece that is intentionally made too long. We had to remove quite a bit of material (a little at a time) to get the endplay where we wanted it.
5. In order to check the endplay, the outer plate must be installed to the base of the timing chain cover. This step is performed without a gasket or silicone. We installed all of the bolts and tightened them until they were snug.
6. Now, attempt to move the camshaft forward and backward with a long, straight screwdriver. Comp Cams suggests 0.004-0.010-inch of endplay, so it’s best to measure with a dial indicator, using the access hole in the center of the Comp Cams timing chain cover.
7. It’s hard to eyeball 0.005-inch, which is the endplay we were shooting for, so it took some finesse with sandpaper to get the perfect fit. We sand a little at a time until we hit our number.
8. After all of the steps of checking camshaft endplay, don’t forget to put a little bit of red Loctite on the camshaft bolts. These bolts are only torqued to 20 ft-lb, so thread locker is suggested on any cam swap.
9. Now that the endplay is set, you can go back and torque down the hardware one last time before the outer timing cover plate goes on.
10. Comp Cams suggests a thin layer of silicone on the outer plate, so we smeared some high-temp RTV on the mating surface. If you use too much sealant, it will get pushed out as the bolts are tightened due to the machined mating surfaces.
11. We performed our endplay measurements with no gasket or silicone, because the thickness of the silicone is immeasurably thin when the bolts are tightened.
12. Once the cover is completely tightened, it’s a good idea to double-check the endplay. Then, it’s time to install the threaded plug for the center access hole.
13. The Comp Cams two-piece billet aluminum timing chain cover comes with two timing pointers. We chose the appropriate pointer and threaded in the two supplied bolts to secure it.
14. Comp Cams supplies button head hardware for the water pump inspection plate. The new timing chain cover is a little bulkier than the stock steel unit so the new bolts free up some much-needed space and put the finishing touch on our install.