How Do I Set Initial Valve Lash on a 454 Chevy?

Written by chris stevenson
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How Do I Set Initial Valve Lash on a 454 Chevy?
The 454 Chevy big block engine was very popular in the past, and still is today. (Red and Chrome engine image by Digital Photique from

The big block 454 Chevy engine was very popular during and after its production. It was nearly unsurpassed in the horsepower and cubic inch department. Many Corvettes produced in the early part of 1970 had the 454 engine installed in them. Some 454s can still be found in dismantling yards today, although most have probably been restored and now power many classic and muscle cars on the road. They certainly had their place on the racing circuit, as well as in the normal passenger car. Adjusting the valves on the 454 can take a little time and patience, but it can be performed by the ordinary DIY mechanic or vehicle owner.

Skill level:

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Things you need

  • Wheel chocks (wood blocks)
  • Socket set and wrench
  • Feeler gauge
  • Oil deflector clips
  • Shop light (if applicable)
  • Rags
  • Assistant
  • Slot screwdriver
  • Chalk
  • Owner's manual

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  1. 1

    Set the vehicle in park or neutral with the emergency brake engaged. Chock the wheels, both front and back, with some wood blocks. Open the bonnet and hang a bright shop light in a position to see the engine compartment clearly.

  2. 2

    Look at the distributor cap, sitting near the back firewall. Look at the first plug tower on the left side of the distributor cap adjusting window. This will be the number 1 plug location. To make sure, trace that wire to the front of the engine. As you are facing the engine, the number 1 plug will be the first plug on the right side. Make a chalk mark on the block surface where it aligns with the number 1 plug tower position on the cap.

  3. 3

    Remove the distributor cap with the slot screwdriver and lay the cap aside, or tape it out of the way. Have an assistant temporarily turn the ignition key to the "Start" position then back to the "Off" position very quickly--this is called "bumping" the starter. Align the rotor electrode directly over the chalk mark you made on the block, with the bumping method. Once aligned, the starter points should be open. Go to the front of the engine with the shop light and shine it down at the crankshaft pulley. You will want the timing marks on the small metal tab to line up with a notch in the crankshaft. It should already be there. This will be top dead centre--TDC.

  4. 4

    Remove both valve covers with the appropriate socket and wrench. Don't disturb the gaskets, unless you have purchased new ones to replace the old gaskets. The exhaust valve on the number 1 cylinder should just be starting to open. Use a socket wrench and socket to tighten the rocker arm nut clockwise on that exhaust valve, while at the same time using the fingers on the other hand to feel the push rod tension. Twist the push rod in a circular motion while slowly tightening the nut. Just as the push rod refuses to move (or seizes up), stop right there. Now turn the nut clockwise one complete turn inward, or 360 degrees. This will set the lifter plunger in the middle of its travel depth.

  5. 5

    Adjust the rest of the exhaust valves on the number 3, 4 and 8 cylinders with the same procedure you used on the number 1 exhaust valve. Remember that the exhaust valves will be in the same front-to-rear location as the number 1 exhaust valve. See the diagram for the proper firing order and cylinder location. Now adjust the intake valves on cylinders number 1, 2, 5 and 7 in the same manner.

  6. 6

    Rotate the engine one full turn around, so the crankshaft pulley notch comes up again and aligns with the timing mark tab. This will be the number 6 firing position, and you can confirm this by holding the distributor cap over the distributor and tracing the number 6 plug wire up to the cap tower. The rotor should be pointing at the number 6 cap tower.

  7. 7

    Adjust the intake valves on cylinders 3, 4, 6 and 8 in an identical manner. Remember, this is the number 6 firing position. Now adjust the exhaust valves on cylinders 2, 5, 6 and 7. This completes the procedure for the initial valve lash setting on the 454.

    Replace the valve covers, tightening them down with the appropriate socket and wrench. Wipe away any excess oil on the covers or engine block.

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