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Buick Straight Eight Valve Lash Adjustment

This information is from the 1951 Buick Shop manual.


NOTE:This procedure applies only on Series 40 engines used with Synchro-Mesh transmissions; these engines have plain sleeve valve lifters. All other engines have hydraulic valve lifters, indicated by a label on rocker arm cover, stating - "This Engine Equipped with Hydraulic Lifters."

For maximum performance in engines equipped for adjustable valve lash, it is imperative that the ROAD OPERATING VALVE LASH BE UNIFORMLY .015".

Oil, water and engine temperatures must be stabilize or brought to normal operating temperatures before the valves can be properly adjusted for uniform lash. When an engine is warmed up by running without load in the shop, the oil, water and engine temperatures level off at different points than those obtained on the road; therefore, a wider lash adjustment is required in the shop adjustment.

NOTE:An alcohol base antifreeze in the cooling system will boil before the temperatures become properly stabilize when running engine in the shop; therefore, such anti-freeze must be drained and the cooling system filled with water until valve lash operation is completed, after which the anti-freeze must be reinstalled.

The following procedure must be carefully followed when adjusting valves in the shop, in order to obtain the specified road operating lash.

  1. Loosen radiator cap to prevent excessive water temperature build-up. Start engine and set speed at a minimum of 700 RPM. NOTE:A lower speed during warm-up will not provide proper circulation through the engine to uniformly stabilize the water temperature.
  2. Run the engine for 20 minutes. This will bring the oil, water and engine temperature to a point where change of lash caused by expansion of engine parts will level off and the lash will remain fairly constant for a period of about 10 minutes. During this time the valve lash can be checked and adjusted as required.
  3. Set engine to idle at 350 - 400 RPM. Remove rocker arm cover and make sure that valves are being properly supplied with oil.
  4. Starting at rear of engine, check the lash of all valves with an .017" and an .018" feeler gauge. The .017" feeler gauge should pass between the valve stem and rocker arm without sticking, but the .018" gauge should not pass through.

    CAUTION:Feeler gauges must be smooth and straight.

  5. Where the lash is either too tight or too loose, loosen the lock nut and adjust the ball stud until a slight drag is felt on a .017" feeler gauge placed between the valve stem and rocker arm. Tighten lock nut and recheck lash with .017" "go" and .018' "no go" feeler gauges. Quite valve action depends on uniform valve lash.
  6. Set engine idle at 450 RPM, then stop the engine.
  7. Install rocker arm cover, making sure that gasket is in good condition and properly placed to prevent leakage of oil. Tighten radiator cap.


NOTE:Engines equipped with hydraulic valve lifters are identified by label on rocker arm cover, stating - "This Engine Equipped with Hydraulic Lifters."

Hydraulic valve lifters eliminate the need for service adjustment; however, an initial adjustment of hydraulic valve lifters is required after the valves have been refaced, whenever the setting of the adjusting ball stud is disturbed for any reason, or whenever valve lifters are removed and installed.

If the operation of a valve lifter becomes faulty due to excessive varnish deposits or presence of dirt it may be disassembled and cleaned. As long as a valve lifter operates properly however, it should be left alone. It should not be disassembled and cleaned when removed for other work but should be wrapped in clean paper to avoid entrance of dirt.

Initial Adjustment of Hydraulic Valve Lifters

The initial adjustment of any hydraulic valve lifter must be made only when the lifter is on the camshaft circle (off the cam).

  1. Crank engine over slowly until distributor rotor indicates the affected cylinder is in firing position, which places both lifters of this cylinder on the camshaft base circle (off the cam), so that either lifter may be adjusted.
  2. Turn adjusting ball stud as required until all play of push rod between lifter and ball stud is just removed, and there is no lash clearance in the valve train.
  3. Turn adjusting ball stud down exactly 2 turns. Check to make sure that oil groove on ball stud is at least half way down in rocker arm so that it connects with the drilled oil passage in rocker arm, then tighten the lock nut.
  4. If oil groove on boll stud is not at least half down the rocker arm, turn ball stud down one additional turn (total 3 turns) and tighten lock nut. If oil groove is still too high, it will be necessary to install another push rod or lifter.
  5. When it is necessary to adjust all valve lifters in and engine, time may be saved by aligning the "U.D.C. 1-8" mark on flywheel with index mark in timing hole in flywheel housing, first with No. 1 cylinder and later with No. 8 cylinder in firing position as indicated by position of distributor rotor. Adjust lifters according to the following table:
No. 1 Cyl. Firing
No. 8 Cyl. Firing
Valve No.
Valve No.
#1 Exh.
#2 Inlet
#1 Inlet
#3 Exh.
#2 Exh.
#3 Inlet
#4 Inlet
#5 Exh.
#4 Exh.
#5 Inlet
#6 Inlet
#7 Exh.
#6 Exh.
#8 Inlet
#7 Inlet
#8 Exh.

So, this Sunday, open the garage door crank up the tunes, grab whatever you keep in your cooler and enjoy adjusting your valves.