Model Year: 1965
Subject: Valve Spring Cap Failure - 425 H.P., 396 ci. Engines
Source: Chevrolet Technical Service Bulletin
Number: DR #757
Section: VI
Date: July 29, 1965
TO: ALL CHEVROLET DEALERS
A few field reports have been received of valve spring cap failure on the 425 H.P. 396 Cu. In. Engine.
An engine plant change correcting this problem, entered production on July 26, 1965.
In the event a failure of this type is encountered, remove all of the existing valve spring caps and shims and replace them with the service parts released for the 325 H.P. 396 Cu. In. Engine:
| Part Name | Part Number |
|---|---|
| Valve Spring Cap | 3859909 - Identified by letter "T" * |
| Shim (.015 Thick) | 3875916 |
* Early 425 H.P. Engine Cap is identified by letter "O".
NOTE:
It is mandatory that the shims be changed along with the caps in order to maintain the proper "installed height" of the valve springs. Under no circumstances should shims having greater than .015 thickness be used.
In no case should valve spring caps intended for other engines be used on the 396 Cu. In. engines, because of an interference problem which will occur between the cap and the umbrella oil seal which is installed over the valve stem.
Flat Rate Data
Remove the cylinder head in which the failure occurred, determine what repair action is necessary and use the proper fault rate operation. use operation 06G - 1880 to replace valve spring caps and shims on the other head.
Article ID: 731
Created: August 2, 2014
Last Updated: August 2, 2014
Online URL: https://www.corvetteactioncenter.com/tech/knowledgebase/article/1965-corvette-service-bulletin-valve-spring-cap-failure-425-h-p-396-ci-engines-731.html