How To Adjusting Valve Lash on a Briggs & Stratton Engine

Today we’re going to talk about the setting the valve lash on a common Briggs and Stratton engine. This is something I mentioned in a previous video but didn’t really go into it. Let’s do a little bit more detailed explanation of how to set your valve clearances. This job is relatively easy, once learned but performing it once a year, can potentially save you from costly repairs down the road.

Preparation:
Step 1: So get started I’ve already removed the hood as it gives you a much better access. I’m also going to put down an old towel to catch any oil that comes out.
Step 2: Once we remove the valve cover. Next, I’m going to remove the spark plug boot and spark plug. I’ll show you why in a minute.
Step 3: We can then remove the valve cover the gaskets on these can often be reused, but it may be a good idea to order a new one.
Step 4: Ahead of time, there are four bolts holding the cover on. Now once we get it off, let’s take a moment and familiarize ourselves with the parts that we are going to be dealing with. We have the intake rocker arm on bottom. An exhaust valve on top, these sit in top of the valve and valve springs on the opposite side. We have the two push rods which are moved by the camshaft inside the engine. In the center are the adjustment parts. There is a center screw that has a Torx head this locks the outer hex nut in place. This one here is a T20, but yours may be a different size or even an Allen head type screw to work this adjustment. We want to hold the 10 millimeter nut with a wrench and then loosen the Torx screw after loosening the nuts is free to move, by loosening or tightening the 10 millimeter nut we can make our adjustments.

Adjustment:
But first, we need to get the valves in the correct position. In the present position, we have one rocker that’s loose and one that’s tight. When we revolve the engine to the proper position. both rockers will have some slack in them. This slack is the valve lash or the tolerance you want to adjust to, get the valves in the proper position. We are going the revolve the engine clockwise while placing an object into the cylinder to feel the position of this position. Now for this, you need a small wood or plastic dowel. This will ensure that you don’t Nick or otherwise damage. The position now, many people are afraid to do this, just go slow and carefully follow the position with the dowel as you or a helper revolve the engine as we turn the engine. the position and the dowel will rise and fall as you reach the top of the position’s Arc or there top head center, revolve the engine just a bit more until you just feel the position start to go back down. Then feel the rockers. if you can remove both of them easily by hand. Then you are in the right place. if one is still tight, then you are on the wrong stroke of the engine. so repeat what we just did slowly rotating the engine. Feeling for the next up dead center again. Go slightly past that and check the rockers again. If they are both loose you are in the right spot. We can then use our feeler gauges to check the gap between the rocker, and the top of the valve for this engine. The specs say the intake should be between three and five thousands of an inch. and the exhaust should be between five and seven thousands of an inch.A good practice is to use the middle measurement. so we will use fourth out for the intake and six for the exhaust.

Now every different engine model will have different specs. So look up your specific engine number and look for your specific valve clearance. All the major manufactures should provide this info. Either in your manual under specifications or online.
So I can push the sixth valve feeler into the exhaust. It is tight, but there is room to push it in the valve clearance. Here is already properly adjusted. But let’s loosen this up, so I can show you how to properly adjust it. If it were out, so now we have a big gap between the rocker and the valve. With the locking Torx crew loosened. Let’s tighten the nut until the gap is correct. Once we get it where we want it, hold the wrench still and tighten the locking screw. now remove the feeler and check it again. It may have become too tight or even too loose. But you can just repeat the process until you are satisfied the gap is correct. Remember the feeler should be tight, but not so tight. Then it cannot be removed or reinserted. Repeat the process for the other valve and you are just adjusted your valves. All that left to do is double check that both of your locking screws are tight, put the valve cover back on and replace your spark plug as I said at the beginning. This job is not that difficult. But if you’ve never done it before. It may feel a little daunting, just take your time and slowly go through the steps and you should have no problems.