1960 - 1961 Corvette: Service Bulletin: Hydraulic Valve Lifter Adjustments

Subject: Hydraulic Valve Lifter Adjustments
Model and Year: 1960-61 Engines
Source: Chevrolet Technical Service Bulletin
Bulletin Number: DR #462, Section VI
Date: January 20, 1961

TO: ALL CHEVROLET DEALERS

Effective with the start of 1961 Production on 283 and 348 V-8 engines and 10/4/60 for Corvair engines, long travel lifters have been incorporated. The term "long travel" refers to the available lifter plunger travel between the bottomed length and the extended length. Effective with this change, the available lifter plunger travel has increased from approximately 1/8" to 3/16" plus.

Because of this increased travel of the new valve lifter assemblies, it is necessary that the valve lash adjustments be revised. The long travel lifters must have two (2) turns additional from the point of where there is no push rod end play. If only one (1) turn is used on V-8 engines incorporating long travel lifters, rocker arm stud cutting will likely result. On 1961 Corvairs, with long travel lifters, incidents of valve lifter noise and slow to build up are more objectionable if not adjusted properly to the two (2) turns. Conversely, if short travel lifters are adjusted to two (2) turns, the lifters would bottom out preventing valves from closing. It becomes apparent that it is very important to properly identify the type of valve lifter used prior to adjusting the valves. There are three (3) methods that can be used depending on the specific situations: (1) Production Data, (2) Inspection After Disassembly and (3) Adjustment.

Production Data - The long travel lifters are in all 1961 283 and 348 V-8 engines. They are in 1961 Corvair engines effective 10/4/60 on engine #T-1004.

Inspection - If the engine has been disassembled, long travel lifters may be identified as follows:

Part No.	Source	Use	Identification Marks
5232100	Diesel Productions	283, 348 & Std. Corvair	1 hole body, 1 hold plunger, push rod seat - steel color, plunger retainer - copper plated.
5232110	Diesel Products	All, including H.P. Corvair	1 hole body, 6 hole plunger, push rod seat - copper plated, plunger retainer - copper plated.
3789175	Thompson Products	283, 348 & Std. Corvair	1 hole body, 6 hole plunger, 2 grooves at top of body.

The push rod seat on all long travel lifters is shallower (has less depth) than seats on short travel lifters.

Adjustment

To determine if an engine is equipped with long travel lifters, proceed as follows: Lash all valves initially with one turn. Then make trial adjustments one valve at a time to 2-1/2 turns (1-1/2 additional), with engine running. If engine runs smoothly after lifter has had time to adjust itself, the lifter is a long travel lifter and should be re-adjusted to two (2) turns; conversely rough idle indicates short travel lifter and should be re-adjusted to one (1) turn.

For Service

Long travel lifters #5232110 and #3789175 are available in Parts Stock for all 1961 283 cu. in., 348 cu. in. and Corvair engines. 1955 through 1960 will use short travel lifter #5232410 on all 265 cu. in., 283 cu. in., 348 cu. in. and Corvair engines.

Generally, for production built units, valve lash should be adjusted as follows:

Engine	1960	1961
L-6	1 1/2 Turns	1 1/2 Turns
283 - V-8	1	2
348 - V-8	1	2
Corvair	1	Engines prior to T-1004 - 1 Engines T-1004 & later - 2

Director, Technical Service Department

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.