Menu

Shop

Garage

Cart

Account

Products to Compare (max of 3)
X
Compare These Parts

How to Check and Set Valve Lash

5/22/2020
Add Article To List

Running the valves should be done after every night if racing. This is a good way to detect any early signs of possible engine failure. To get started, you need to remove the valve covers. Once valve covers are removed, inspect it to make sure the cylinder head is free of any debris. Pay close attention to make sure there are no metal flakes or pieces laying in the head. Also, take note of the oil in the head, it should be the same color as when oil was poured into the engine. If the oil has a milky color, this can be caused by an engine where the fuel system was not set correctly. Or if any water is present, you could have more serious issues. There may be some traces of moisture if the air was humid when the engine last ran.

The next step is to remove spark plugs. You do not have to remove the plugs, but it makes it easier to rotate the engine if you do. I like to inspect the plugs once they've been removed. They should have a nice tan or light brown color if the engine was tuned correctly. If plugs are ghost white, the engine was too lean. Dark brown or wet means too rich and black is possibly burning oil.

Now that the plugs and valve covers are removed, we are ready to check valve lash. I like to check by starting with the intake of the number one cylinder and going in the firing order of the engine. This makes it easy to keep track of which valves have been checked with minimal rotating of the engine. Rotate the engine so that the number one exhaust valve just starts to move. You can now check the intake valve. I first spin the pushrod to make sure it spins free. If the pushrod does not spin, it can be caused by no valve lash or being bent. If the pushrod is bent, you need to investigate further what the cause was.

The most common causes are the valve hit a piston, the valve lash is too loose, or there is a lifter issue. As long as the pushrod spun freely, you can check lash. Check with the engine builder or cam manufacturer for the correct lash. Next, insert the correct feeler gauge in between the top of the valve stem and under rocker tip. Speedway Motors offers these Valve Lash Feeler Gauges. This should be a snug fit. If you can spin push rod when the feeler gauge is inserted, the valve lash is too loose. If you have to force feeler gauge in, the valve lash is too tight.

If the lash needs to be adjusted, you will need to loosen the lockset screw inside of the poly lock with your wrench turn poly lock. Once you have the desired lash tighten set, screw inside of the poly lock. Speedway Motors offers this Valve Lash Rocker Wrench and Valve Lash Torque Wrench to make this easier. Adjust the shaft mount rockers by loosening the nut and adjusting with hex key wrench. Make sure the set screw or jam nut is tight when lash adjustment is done. Repeat this step for all intake valves.

Now we move to the exhaust valves. Rotate the engine so the number one intake is ¾ of the way closed. Spin the exhaust pushrod to make sure it is free. Once again, insert the proper feeler gauge above the exhaust valve stem and below the rocker tip. You want the fit to be the same as how we checked the intake, snug, not too tight not to loose.

Repeat this for all seven exhaust valves. After all the valves are set, install the plugs and valve covers. Some cams may require to set lash that the intake is fully open to check exhaust and exhaust is fully open to check the intake. You want the lifter to be on the backside of the cam and not on the ramp of the cam when checking lash. Whichever setting gives you the largest lash is the one you will want to use.

Products Featured in this Article

Related Articles

Speedway Tech Talk - How to Measure for a Racing Suit
by Frank Galusha - Posted in Videos
12/29/2021
EMi Employee Frank and Speedway Motors employee Jeremy demonstrate how to properly measure for a race suit.
How to Choose a Racing Harness
by Charles Aman - Posted in Tech
12/3/2021
Having a difficult time deciding which racing harness to use? With many options to consider from size to closure type, this article will walk you through how to go about choosing the perfect one for you and your race car. Safety first!
Head and Neck Restraint Systems
by Marcus Kennedy - Posted in Tech
8/31/2021
To prevent injury, your racing safety gear must meet the SFI 38.1 specification and fit properly. Learn how to choose a head and neck restraint system for competitive motorsports in our buyer's guide.
Selecting Quarter-Turn Fasteners
by Jason Lubken - Posted in Tech
8/13/2021
There are several types of quarter-turn fasteners used in the performance automotive aftermarket and in this buyer's guide we'll help show you the correct fastener for your application and how some of the most common types of fasteners are used.
How to Vinyl Wrap a Race Car
by Caleb Filipi - Posted in Tech
8/6/2021
How to vinyl wrap a car with this guide on using a heat gun on your race car. Learn how to remove creases and the best temperature settings.
Tire Grooving and Siping Tips
by Eric McMillan - Posted in Tech
7/21/2021
Learn some helpful tips for using your tire groover as well as what direction to cut your grooves and sipes for maximum side bite and forward bite on your dirt circle track race car.
How to Use a Stud Extractor Tool
by Steve Lewis - Posted in Tech
6/15/2021
Broken exhaust studs are a common problem. This article describes what you need and how to remove a broken stud from an exhaust manifold. Learn how simple it is to remove broken or stubborn studs with a Titan Tools stud extractor tool.
Racing Shocks 101
by Speedway Tech Team - Posted in Tech
6/8/2021
Get a good foundation on racing shocks and their different functions. Learn about the fundamentals and the pros and cons between various types of shocks available.
How to Choose Racing Wheels
by Speedway Tech Team - Posted in Tech
6/8/2021
Check out this article to learn about why it's important to choose the right wheels for your race car and which types to choose.
Selecting the Proper Tear Offs for Your Helmet
by Eric McMillan - Posted in Tech
5/3/2021
This comprehensive guide will step you through the process of choosing the correct tear offs to fit your helmet as well as how to install them.
Error
X
Note
X
Ok