Model Year: All 1974 Passenger Cars and Light Duty Trucks Equipped with 454 cu. in. Engine
Subject: Soft Push Rod Guides
Source: Chevrolet Dealer Service Technical Bulletin
Number: 74-T-29, Section: VI
Date: May 1, 1974
To: All Chevrolet Dealers
Excessive valve train noise on 1974 models equipped with a 454 cu. in. engine, may be due to soft push rod guides. Installation of soft push rod guides result in rapid wearing of the push rod guide slot by the push rod. This allows the push rod to move out of alignment. A loud ticking noise while the engine is running indicates this condition.
Engines built on the following dates that bear the following identification codes could have been assembled with soft push rod guides.
| BUILD DATE | ENGINE IDENTIFICATION CODE |
|---|---|
| 10/30/74 | T 1030 |
| 10/31/74 | T 1031 |
| 11/01/74 | T 1101 |
| 11/02/74 | T 1102 |
| 11/05/74 | T 1105 |
The engine identification code appears on the pad at the front, right-hand side of the cylinder block.
In each such encounter is is important that the push rod guides be thoroughly inspected. visually inspect each guide (8 per engine) for signs of wear. Check hardness by trying to file each guide on a non-critical area. Properly heat treated guides will resist filing; soft ones will be easily cut.
Replace any push rod guides that are worn or soft. Inspect other valve train components for damage caused by soft push rod guides and replace as required.
Chevrolet Motor Division
General Motors Corporation
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.
Article ID: 837
Created: August 9, 2014
Last Updated: August 9, 2014
Online URL: https://www.corvetteactioncenter.com/tech/knowledgebase/article/1974-corvette-service-bulletin-soft-push-rod-guides-837.html