Valve Lash Adjustment

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COMP GoParts™
1-800-976-9376
3406 Democrat Road
Memphis, TN
38118

Office Hours
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Go-Parts™ Complete Valve Lash Adjustment Instructions For Modified Class Briggs & Stratton™ 5 HP Engines

"Valve Lash" describes the clearance (space) between the bottom of the valve stem and the top of the lifter stem. If you do not adjust the valve lash, your valves will not close completely when the engine reaches operating temperature due to the expansion of metals. You will remove material from either the valve stem or the lifter stem to create this clearance.

Note: Remember that your goal is a hi-performance racing engine, it is in your best interest to follow these instructions. By not following these simple steps, you may reduce horsepower, efficiency, and the performance of your engine.

Note: You can not adjust valve lash accurately without a valve guaging tool and a feeler guage.

We will assume at this point that you have installed your camshaft properly, that your cam is degreeing in properly, and that your valves are placed into the valve guides.

Rotate the crankshaft until the piston is at TDC (top dead center) so that both valves are fully closed.

Using a feeler guage, select the correct thickness according to your camshaft's application sheet and insert it between the intake valve stem and lifter stem. If the valve moves up, you need to remove material from it until there is no movment.

Remove the valve, place it in a valve guaging tool, and remove only a slight amount of material. (A valve guaging tool ensures that the stem will sit squarly on the lifter when finished)

Place the valve back in the valve guide, and use the feeler guage to re-check the lash.

If the valve moves up, remove it and repeat these steps until there is no vertical movment. Remove only very slight amounts of material from the valve stem at a time, excessive valve lash will restrict air-flow and reduce engine performance.

Now, repeat the procedure for the exhaust valve.

When finished, you will be ready to check the "Off The Seat" valve openings and closings given on the camshaft's spec sheet.

If there is too much valve lash when you begin or if you introduce too much valve lash you will have to start over with a new valve, start with a new lifter, or remove material from the valve seat so that the valve sits lower. The easiest remedy is to start with a new valve.
Using a new lifter requires removing, re-installing, and re-degreeing the camshaft in addition to replacing the lifter.
Removing material from the valve seat accurately requires special equipment usually found only in engine shops.

If you have any questions concerning installation or proper use of your new Go-Parts™ products, call us toll-free at 1-800-976-9376.

Cam cards and application sheets are also available by calling Go-Parts™' tech line toll-free at 1-800-976-9376.

IMPORTANT: Take the time to make sure that your camshaft is installed and clearanced properly.

The following instructions are designed to help you properly adjust your valve lash. It is a necessity for you to properly and accurately install your camshaft in the engine to insure proper performance. All measurements taken can be verified against Go-Parts™ cam card and application sheet.