Excessive valvetrain chatter, oiling issues, and the occasional bent valve from over-revving the engine can all be attributed to improper valvetrain setup. Setting up the valvetrain on your mill doesn’t have to be difficult. Taking your time and being aware of what you are doing will keep your engine strong, healthy, and out of the machine shop from a broken rocker or pushrod. A bit of knowledge and labor on your part can go a long way when positioning the valvetrain for long-term durability.
When it comes to piecing together a mill for your project vehicle, penny-pinching is what it’s all about. Performing any job yourself not only saves you money but gives an overall sense of achievementit’s what this game is all about. We recently took on our 396-inch big-block, which just had its iron heads assembled. All it needed was the new roller rockers to complete the valvetrain so we could get the car back on the street. Luckily, it’s a hydraulic setup, which means no constant checking of the rocker arm lash once it’s set. Do it right the first time and you can forget about it.
Whether it’s sustained high rpm or short bursts of the throttle, the valvetrain is designed to take a lot of abuse and punishment. If set up properly, it should outlast everything in the engine and be the last thing you ever replace. With a set of COMP 1.7:1 roller rockers in hand, we were ready to complete the valvetrain on the 396. Follow along as we illustrate the process and include quick reminders that will make your next valvetrain assembly that much simpler.
1. Normally, the first step...
1. Normally, the first step is to remove the old stamped-steel rocker arms from the cylinder heads. However, this particular 396 big-block was in the process of being reassembled so that wasn’t necessary. Our big-block foundation sports GM iron heads with dual COMP valvesprings, 10-degree locks with retainers, and factory guideplates.
2. To check for pushrod length,...
2. To check for pushrod length, we installed the 1.7:1 roller rocker onto the rocker stud. Then we determined where the roller tip landed in relation to the tip of the valve stem. The goal is to get the center of the tip onto the center of the stem.
3. Next, we checked the rocker...
3. Next, we checked the rocker arm stud thread by taking note of the rocker as it sat on the rocker arm stud. Our rocker arm stud was too short and would not allow enough thread for the poly locks. We needed to swap to a longer style.
4. It’s always best to remove...
4. It’s always best to remove only one stud at a time from each pair of guideplates. This prevents having to readjust the guideplates. We swapped to a set of ARP 135-7102. We used an 11/16-inch socket to remove the old rocker arm screw-in stud (7/16-inch).
5. For good measure, it’s...
5. For good measure, it’s always a good idea to apply a small amount of thread sealer to the threads of the rocker stud. This will prevent any water from leaking into the cylinder head. We then torqued each set to the recommended 65 lb-ft.
6. The next step is critical...
6. The next step is critical when installing the rocker arms. We made sure to position the trunnion (axle) in the up position. The trunnion on the rocker arm has a specific cutout designed to seat the poly lock in the correct position. Fail to do this and the poly lock will ride in the incorrect spot and break.
7. Next, we applied a liberal...
7. Next, we applied a liberal amount of Royal Purple assembly lube to the pushrods, rocker studs, and tops of each valve. This will prevent a dry start-up situation once the engine is fired up.
8. Once each rocker arm was...
8. Once each rocker arm was seated onto the pushrods we installed each poly lock onto the rocker studs. For the time being, we fastened them down only hand-tight.
9. Lashing the valves isn’t...
9. Lashing the valves isn’t as tedious a process as you might think. For hydraulic roller setups like this 396, each poly lock requires a zero lash. This means tightening the poly lock down with a 5/8-inch open wrench until the pushrod stops spinning in the rocker arm pocket. Then, preloading the lifter requires an additional 1/4 to 1/2 turn. Next, throw on the valve coverswe’re done!