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The following technical bulletins were published by AERA.


         Method To Restore Worn Cam Gear Thrust Area On
                       Some Engine Blocks

Many late model engines (Chevrolet small block and 6.5L (396
CID), Dodge & Plymouth 3.4L (225 CID), Oldsmobile 4.0 & 4.3L (425
& 455 CID), Buick 4.1L (401 CID) and others) do not have camshaft
thrust washers, but depend upon the mesh of the distributor drive
gear to retain the camshaft.  Often the cam gear or sprocket
causes the front of the block to wear to such an extent that
repair is needed to return the block to service.

A relatively easy yet effective repair is suggested:

     (1) Make a metal brush (similar to a cam bearing drive plug)
     approximately 2 long with the outside diameter to fit the
     cam bearing housing bore.  Provide a slight taper on the
     O.D. to prevent the bushing from going all the way through. 
     Drill an inner hole in the bushing to accept a valve seat
     installation pilot.  Modify a valve seat cutter shank to be
     turned by 1/2 electric drill and attach a cutter head
     proper diameter to match the O.D. of the worn circle.

     (2) Cut the front of the block the depth of a Y91
     Continental main bearing thrust washer.  The O.D. of the
     thrust washer should be machined to press fit in the
     machined counterbore.  The I.D. of the thrust washer should
     be machined to fit freely over the cam bushing.  The Y91
     thrust washer should then be installed.

After tooling up for this operation, the entire procedure should
take no more then five minutes and the only cost is that of the
thrust washer.

NOTE: Depending upon your valve seat equipment, it may be
necessary to change the above tooling to accommodate your

                                     The AERA Technical Committee

April 1973 - SPB 18



                     Flywheel Specifications

The following flywheel specifications may be used as reference
when surfacing flywheels.

                   Type of 
Manufacturer       flywh. Specs.          Comments

BMW                Step   .013 - .015
Datsun             Step   .003 - .005   No groove
                   Flat                   With groove
Datsun 240Z        Step   .010           With groove
Fiat Spider 1600   Step   .018
Ford Falcon        Cup    .018           6 Cylinder engines
Ford Courier       Cup    .285
                   Cup    .310
Ford Ranger        Cup    .003           V6 Cylinder engines
GM                 Cup    .125
GM - Buick         Cup    .125           V6 Cylinder engines
GM - Spirit        Cup    .195
Honda              Cup    .030           Small cup
                   Cup    .100 - .104   
                   Cup    .785           Long alignment pins
                   Cup    .900            Short alignment pins
Honda Accord       Cup    .615           
Mazda              Cup    .062           Rotary engines
Subaru             Cup    .785
Toyota             Step   .018 - .022   Large alignment pins
                   Cup    .055           Small cup
                   Cup    .965 - .970    Tercel, large cup
                   Step   .040           Tercel, step
                   Step   .020           Land Cruiser
VW                 Cup    .945           Air cooled, 6 Volt
                   Cup    .830           Scirocco
                   Cup    .835           Rabbit/Golf
                   Cup    .982           Air cooled bus engine
                   Cup    .830           Air cooled engine
                   Cup    .885           Air cooled engine

Specifications listed for Step type flywheels refer to the
height of the wear surface above the pressure plate mounting
surface.  Specifications for Cup type flywheels refer to the
height of the pressure plate mounting surface above the wear

                                     The AERA Technical Committee

February 1988 - SB 153



                                             Crankshaft Identification On
                                             GM 3.3L 3300 Buick Engines

The AERA Technical Committee advises caution when replacing the crankshaft on GM 3.3L engines.  Currently there are two different crankshaft designs and with four different casting numbers used in this engine.  While it is acceptable to interchange certain crankshaft castings, do not cross year and design designations.
The first design crankshaft uses a two-piece rear main seal while the second design incorporates a one-piece full-circle seal. Each crankshaft design uses a unique seal surface dimension prohibiting interchange.

The easiest way to identify the different crankshaft castings is to count the number of flywheel retaining bolt holes: one has six (6), the other eight (8).  The chart below list additional differences on GM 3.3L crankshafts: 

Years Used     Casting #S     Rear Seal      Rear Bolt Flange

1989-90        1235413, 694   2.656         six (6) bolt holes
1991-93        817*, 4817     3.228         eight (8) bolt holes


                                                                       The AERA Technical Committee


                                             Main Bearing Knock On
                              GM 3.3 & 3.8L (Buick 3300 & 3800) Engines

AERA members report knocking noises coming from the front of GM 3300 & 3800 Buick engines.  The noise is most noticeable when the engine has reached operating temperature.  One possible cause for this knocking noise may be from excessive oil clearance at the front main bearing location.

Diagnosing excessive main bearing clearance is easily done by removing the accessory drive belt from the engine after it has reached operating temperature.  If the noise diminishes when the engine is started again, front main bearing clearance may be more than .0012 (.030mm).  The clearance may be reduced by installing .001 (.025 mm) undersize main bearings.  GM permits the use of only one bearing shell half in the cap, but warns not to reduce
clearance below .0008 (.020 mm).

GM specifies the main bearing clearance as .0008-.0022 (.020- .055 mm).  AERA suggests machining the crankshaft main bearing journals and the main bearing housing bore so that the minimum allowable clearance is maintained, avoiding the possibility of  main bearing knock.
                                                                           The AERA Technical Committee


                                        Rear Main Rope Seal Alternative

The AERA Technical committee supplies the following information on a rear main rope seal alternative. The information provided below was collected over many years. This information is feedback from people like you. People tell us these seals have worked fine for them but will they work for you? AERA expresses no guarantee that they will work 100% of the time but the seals listed below have proven to be the most successful. 

During installation, offset or rotate each seal half ? to 3/8 from the main cap parting line. Place dab of anaerobic gel on the ends of the seals that will butt together. Lubricate the seal lip with straight 50 W oil or a bearing assembly lube as those lubes that will stay in place until the engine is started. Seal manufacturers do not recommend white grease alone, because they have seen too many failures from dry startups. This is especially true in rebuilt engines that sit on the shelf for long periods of time before being put into service. This is why you may have seen chunks torn out of the contact face of the seals that have 
leaked. If you have ever seen a Ford 390 or 460 tear the whole lip off the seal, it happened because it was dry started and stuck to the crankshaft.

Engine to       Detroit   Enginetech     FM            ROL             Victor            Actual
Be repaired                                                                                                  Application

Buick 231      17200      S-1389      BS-40613     RS-29470    JV-742-V     Jeep 225
Buick 350      17043       N/A          BS-40032    RS-29130      JV-618      Ford 460
Buick 455      17042        N/A         BS-30135     RS-29050    JV-730       Ford 200
GM 265/283   17053      S-0629     BS-13241     RS-29005    JV-728       Chev 250*
Caddy 365     17032      S-1196     BS-40245     RS-29040    JV-606       Dodge 318
Ford 312        17032      S-1196     BS-40245     RS-29040     JV-606      Dodge 318
Olds 260 307
330 350 403   17175       N/A          BS-6141      RS 29310        N/A         Ford 292
Olds 350D 
400 425 455   17043       N/A          BS-40032    RS-29130      JV-618     Ford 460
Pontiac 301   17091       N/A          BS-40048        N/A            JV-616     GMC 637
Pontiac 350   17043       N/A          BS-40032    RS-29130      JV-618     Ford 460
Pontiac 455   17008       N/A          BS-40012    RS-29115      JV-600     Caddy 500

* Install a .090 (2.290 mm) diameter wire in the groove, behind the seal.

It has also been reported that replacing the timing case rope seal with a National seal Part #450446 has proven effective on 455 Buick engines.                                                                                                                           On engines which use rope anti-rotation holes in the block and cap, fill them with RTV and let dry over night. 

                                                                             The AERA Technical Committee


                                           Low Oil Pressure During Idle On
                            General Motors (Buick) 3.8L (231 CID) Engines

Hot idle low oil pressure is a common complaint directed to General Motors' (Buick-built) 3.8L (231 CID) V6 engines.  Some AERA members report hot idle oil pressure as low as 7 pounds, and oil pressure of 25 pounds or more when above idle.  Changing the pressure relief spring affects oil pressure at higher RPMs, but
not the idle oil pressure.

General Motors (Buick) advises that a low or no oil pressure condition at idle may be caused by a sticking pressure relief valve.  Forcing the relief valve into the bore as far as possible several times will usually free it up.  A small chamfer should be formed on the outer edge of the valve (Figure 1) to help it remain free.  General Motors (Buick) further advises that the oil filter adaptor gasket covers an oil channel port in the timing cover and it may have a tear in it.  Pieces of the gasket may be sticking the relief valve.  General Motors (Buick) claims that
replacing the gasket with newly designed GM gasket #25529916 eliminates this problem.

However, field reports from AERA members indicate that this is not the problem in most cases since it primarily occurs in newly rebuilt engines.  The problem seems to be centered around two areas:  the oil pump and the cam bearings.

AERA members are using several methods to improve the oiling system.  The feed line to the oil pump on pre-1980 blocks is being enlarged 1/2 (.005) as General Motors (Buick) has done with blocks since 1980.  General Motors (Buick) also increased the size of the oil pick-up tube.  Some aftermarket suppliers are
using the larger diameter tubes for the pre-1980 engines.  Be sure that the pickup tube you use has a 1/2 ID to adequately supply this enlarged gallery.  Sharp edges and 90 degree turns must be deburred and radiused.

The oil pump housing and gear thrust plate must be checked very closely for wear and scratching.  Housings within specifications but are scratched should be replaced, and thrust plates should be resurfaced or replaced.  Most aftermarket suppliers have a cast iron plate to replace the OE aluminum plate.

A high-volume oil pump kit has been developed by the Melling Tool Company and is available through most aftermarket suppliers.  The kit requires drilling two holes to install alignment pins for a plate that increases the height of the housing.  This increased height allows the use of taller oil pump gears, and the kit can usually be installed on an engine that's still in the chassis.

It is believed that another cause of dropped oil pressure is that the cam bearings spill too much oil back to the crankcase. General Motors (Buick) engineers increased the size of the oil hole in the bearing because of lengthened oil change intervals.  Thicker, contaminated oil had difficulty flowing through the original small holes, but the larger holes allow too much oil to
spill when clean oil is circulating.

Some AERA members drill new, smaller oiling holes to reduce this spill and increase oil pressure.  Caution is urged because of the potential problems that thick, contaminated oil will cause.  Another alternative is the use of a new camshaft bearing that is grooved on the backside.  This allows you to install the oiling hole opposite the supply hole.  The oil is then fed to the camshaft at the thrust side.  Reduced wear and increased oil pressure over the life of the engine is the result since the cam bearing is no longer receiving oil at the point of maximum clearance.

Other AERA members increase idle oil pressure by just reworking the supply line in the block and using the high volume kit.  All members stress the importance of resurfacing or replacing the gear thrust plate.  AERA members using these methods are reporting hot idle oil pressure in the 15 to 20 pound range.

Since the housing is a part of the timing cover, many customers are reluctant to replace this costly part.  Educate your customers to the consequences of using a worn oil pump housing and urge them to have it thoroughly checked. 

                                                                     The AERA Technical Committee

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